Nanotechnological Advances in Catalytic Thin Films for Green Large-Area Surfaces

Biran Ay, Suzan; Kosku Perkgoz, Nihan

doi:https://doi.org/10.1155/2015/257547

Journal of Nanomaterials

On this page

Abstract Introduction Conclusions References Copyright Related Articles

Review Article | Open Access

Volume 2015 | Article ID 257547 | https://doi.org/10.1155/2015/257547

Nanotechnological Advances in Catalytic Thin Films for Green Large-Area Surfaces

Suzan Biran Ay¹and Nihan Kosku Perkgoz²

Academic Editor: Stefano Bellucci

Received23 Apr 2015

Revised21 Aug 2015

Accepted23 Aug 2015

Published17 Sept 2015

Abstract

Large-area catalytic thin films offer great potential for green technology applications in order to save energy, combat pollution, and reduce global warming. These films, either embedded with nanoparticles, shaped with nanostructuring techniques, hybridized with other systems, or functionalized with bionanotechnological methods, can include many different surface properties including photocatalytic, antifouling, abrasion resistant and mechanically resistive, self-cleaning, antibacterial, hydrophobic, and oleophobic features. Thus, surface functionalization with such advanced structuring methods is of significance to increase the performance and wide usage of large-area thin film coatings specifically for environmental remediation. In this review, we focus on methods to increase the efficiency of catalytic reactions in thin film and hence improve the performance in relevant applications while eliminating high cost with the purpose of widespread usage. However, we also include the most recent hybrid architectures, which have potential to make a transformational change in surface applications as soon as high quality and large area production techniques are available. Hence, we present and discuss research studies regarding both organic and inorganic methods that are used to structure thin films that have potential for large-area and eco-friendly coatings.

1. Introduction

Structuring thin films at nanometer scale enables distinctive mechanical, chemical, and physical surface functionalities including higher surface area, self-cleaning, photocatalytic, antibacterial, nontoxic, antifouling, hydrophobic, and oleophobic properties [1–6]. In addition to these, abrasion resistant and mechanically resistive features are important for durable and functional applications to save energy and provide clean air and water [7, 8]. Thus, green approaches are essential considering the population increase and growth in industry and their inevitable impact on the world’s natural resources. Such smart and functional coatings can be utilized in different fields including construction industry to enhance material properties and provide energy conservation [9], flexible surfaces with high hydrophobicity [10] and high conductivity [11], large-area solar modules [12, 13], structures with high mechanical strength [14], bioremediation [15], textiles [16], biomedical applications [17], antifouling [18], and photocatalytic applications [19, 20]. Hence, with their superior surface properties, the nanostructured coating applications can be extended from self-cleaning processes [21–23] to the protection of cultural heritage assets [24] and food packaging [25].

In this review, we specifically focus on catalytic nanostructured large-area thin films that have potential to provide solutions for environmental pollution problems either at present time or in the future after some further advancement. These will include photocatalytic coatings since large-area photocatalytic applications offer potential solutions such as self-cleaning and receive industrial attention also regarding their additional properties (e.g., antibacterial, hydrophobic, and oleophobic properties). However, to examine organic and inorganic methods at once, catalytic enzymatic methods of implementing potentially green and low-cost coatings have been reported considering recent advances in genetic engineering and reduced cost of enzymes [26–29]. With the advances in the last years, incorporating biocatalysts in thin films and coatings has been receiving considerable attention by different research groups due to superior biodegradability, selectivity, and less by-product formation compared to inorganic catalysts [30–32]. To remain in the scope of the topic, only the nanoscale and eco-friendly catalytic process research studies are included. This review excludes prior thin film nanoelectronics research work that cannot be associated with eco-friendly applications and focuses on novel methods to improve solid film catalytic efficiencies preferably at low cost for wide spread usage.

2. Increasing the Performance of Catalytic Thin Films

2.1. Methods for Enhanced Photocatalytic Efficiency

For about 40 years, photocatalysis in the presence of metal oxides [19, 33–37] and for the last decade enhancement of photocatalytic reactions in the presence of nanostructured particles have been investigated [38–43]. Different photocatalytic metal oxide semiconductors have been studied for numerous applications, some of which are water splitting [44, 45], oxidation of organic and inorganic pollutants [46–48], photocatalytic destruction of gaseous organic pollutants [49, 50], and photo disinfection [51]. Additionally, such photocatalytic materials have been used for different applications such as solar cells [52], chemical sensors [53], photoelectrochemical cells [54], and other novel devices [55]. Such a wide range of applications is viable for metal oxides because of their variety of electronic and structural possibilities allowing possible compounds with magnetic, conducting, insulating, or semiconducting behavior [56]. Among the metal oxides, in consequence of its specific properties such as high photocatalytic activity, stability and inertness together with its low cost, and nontoxicity, TiO₂ has been exploited most thoroughly by a vast number of researchers and associated fundamental studies have been already discussed by several review articles [19, 20, 57–59].

There are numerous publications and considerable review reports for metal oxide photocatalysis in aqueous environment [48, 60, 61], which clearly shows that using metal oxide photocatalysis is a viable option for decomposing many inorganic contaminants including heavy metals as well as for destroying the microorganisms such as bacteria and viruses [62–65]. In these studies, although complete mineralization in remediation processes can be achieved, the processes are long, expensive, and not practical and lack flexibility to manufacture devices. Thus, photocatalytic reaction in solid form is an important requirement [66]. By this way, utilization of the metal oxides for large-area applications will be enabled.

Apparently when photocatalytic particles are immobilized in thin films instead of being used in water environment, the activation environment is to be regulated cautiously due to the inherent reduction of photocatalytic area [67] and the emerging recombination problem [68, 69]. Photo-induced carriers are transmitted at the boundary of the photocatalyst and the adsorbed material and reaction efficiency is reduced for solid films because of reduced effective catalyst surface [57, 70]. Photocatalytic activity is found to improve with increasing TiO₂ surface area and understandably higher UV light intensity is observed to have a positive effect on photocatalytic reactions [62]. Another important factor is the rather large energy bandgap of the common metal oxides for efficient optical absorption of solar spectrum. The most commonly used metal oxide, TiO₂, can absorb less than 5% of the solar energy irradiation if no modification is carried out [71]. Although photocatalyst with large bandgaps can still be applied effectively, obviously improving the light response range will make an important impact on such coatings to become economically viable for large areas. Hence, up to date, different techniques for better light absorption are implemented to overcome the issues related with wide application of such photocatalytic coatings [72]. Figure 1 shows the schematic diagram of methods, mechanisms, and challenges for higher efficiency of photocatalytic reactions in thin films. For photocatalytic functionality to become available for green applications with self-cleaning or antibacterial properties, it is essential to obtain high photocatalytic efficiency at large areas for the visible spectral range. Therefore, first of all, one must choose the photocatalytic material since its structural characteristics such as its crystallinity, geometric, and electronic properties are crucial to determine the overall performance [41, 73]. As it will be reviewed in more detail, size effect, in other words using nanoparticles, is of great importance for increased efficiency in solid films [74]. Another essential criterion for better performance is related to surface properties and, among the techniques to modify the surface features, nanostructuring techniques are promising [75]. Again, as it will be examined with a closer look, synergistic effect with a cocatalyst can improve the activation of redox radicals, decrease recombination of the generated electron-hole pairs, enhance carrier diffusion in bulk, and increase carrier transfer to surface. In general, the utilized techniques can enable changes on the surface or the bulk of the photocatalytic material or they can transform the material’s electronic structure. Thus, there are numerous production, doping, and hybridization techniques to enhance the photocatalytic activity and add other functionalities. Using such techniques, the active spectral range of photocatalytic materials can be controlled and electron-hole generation, recombination, and diffusion reactions can be regulated [76]. In this respect, nanotechnology can potentially present solutions to the current problems related to reaction efficiency and recombination rate in photocatalytic processes such as bandgap engineering, building heterostructured junctions and integration with cocatalysts. Additionally, to utilize the visible light from the sun, and hence improve the photocatalytic performance under solar light, nanostructure design is of great importance [77].

2.1.1. Nanosize Effect

In the case of working with photocatalytic activation in aqueous environment, typically, photocatalytic particles are added into water and are later recovered from the environment after the photocatalytic process is completed, which increases both operation duration and expenses. For the processes to be less-priced and to take less time, these particles are immobilized in thin films, which also leads to new functionalities for coatings with innovative properties, which is not otherwise possible in aqueous environment. On the other hand, because photo-induced carrier transfer happens at the boundary of the photocatalyst material and the adsorbed material [70], immobilization is expected to lower the catalyst surface and degrade the photocatalytic effectiveness [68, 78]. For example, when photocatalytic efficiency is compared in different forms of titanium dioxide between the forms of inorganic fiber, sputtering, slurry, and sol-gel, the slurry structure showed the highest performance [68]. The reason suggested for the lower efficiency in solid form is the higher recombination rate because of ionic specimen, relatively smaller active surface, and less chance of ion exchange [79]. Hence, the main problem in immobilization of metal oxides is the relatively low photocatalytic efficiency [80] for large-area photocatalytic applications to be widely used and provide solutions to pollution and environmental remediation. In this respect, one of the first approaches that aim to increase the photocatalytic efficiency of photocatalytic solids has been via employing nanostructured semiconductors, increasing charge carrier transfer on the reaction surface, or decreasing the recombination rate of electron-hole pairs [81, 82]. Thus, using nanoscale photocatalytic particles is beneficial to overcome the efficiency reduction because of their high surface-to-volume ratio [71, 83] when photocatalytic materials are immobilized in thin films and when it is expected for the photocatalytic activity to take place on the surface of a solid structure [84]. Specifically, the photochemistry of nanocrystalline metal oxides has taken great interest where the photophysical properties have been investigated thoroughly [74, 85, 86]. Transition between molecular and bulk phases occurs when the diameter range is 1–10 nm and consequently different properties are obtained thanks to quantum effects [87].

For the case of bulk materials, the kinetic energies of photoexcited electrons can take various values as the density of states in the conduction band is rather high [85]. However, when the size of the particles gets as small as the size of the first excited state (or smaller), the generated electron-hole pairs are enforced to move to an upper kinetic energy state [88]. Therefore, reduction of particle sizes to smaller than a threshold brings confined carriers in a potential well, similar to “particle in a box” case, which includes quantum mechanically interacting nanoparticles [89]. Hence, particle size directly affects the redox potential of holes in the valence band and that of electron in the conduction band [90] where holes and electrons are present on the nanoparticle surface together enabling simultaneous oxidative and reductive reactions [91].

Up to date, nanoparticles with various geometries and structures have been demonstrated: for example, 3D-ordered films of titania hollow spheres with adjusted sphere diameters have provided higher absorbance of visible light resulting in photocatalytic enhancement [92]. An ideal photocatalytic thin film should be stable, be of low cost, and allow for safe processes with high photocatalytic efficiency. Semiconductor metal oxides that are used as catalysts utilize the energy of incident light that exceeds the bandgap of the metal oxide material and produces electron-hole pairs. Upon the optical excitation of the material system by a photon with energy equal to or higher than bandgap energy of the photocatalytic system, electron makes transition from the valence band to the conduction band and leaves a hole in the valence band. This photo-generated electron-hole pair then diffuses to the surface and initiates a chain of reactions. As a result, these excited states supply H⁺, OH⁻, H₂O₂, and species, which degrade the existing pollutants. In fact, most common metal oxides have large bandgaps, which decrease the efficient utilization of solar light. This is due to the small portion of the UV light in natural sunlight (5%–8% of the solar spectrum at sea level) [93] reducing the fraction of the generated electron-hole pairs, which limits the degradation of the organic materials. Another problem is related to losing electron-hole pairs in a very short time as recombination can be critically high when the conditions such as pH of the environment, size of the photocatalytic material, and adsorption are not appropriate [94]. Therefore, nanotechnological methods to improve the catalytic efficiency is appealing as surface area for catalytic reactions can be increased; the bandgap of the catalyst can be modified or recombination rate can be lowered.

2.1.2. Hybridizing with Other Systems

There are various surface structuring techniques including porous nanosphere, nanotube, nanorod, and nanowire formation to achieve surface functionality [71, 95]. Also, hybrid nanostructures, which include photocatalysts grown on graphene flakes [96–98], microspheres coated with photocatalysts [99], polymer coated photocatalysts [100], hollow spherical hybrid photocatalysts [101], and other composites [102], have appealed considerable attention. Among these, as future prospects, 2D material hybridized photocatalysts are promising from perspectives of large-area applications and high efficiency.

Figure 2 shows different hybrid models for increasing the photocatalytic efficiency. It is possible to use the interaction of plasmonic photocatalyst with a graphene sheet, facilitating enhanced absorbance in the visible region as a result of surface plasmon resonance absorption of Ag nanocrystal [103]. Figure 2(a) shows Ag@AgCl/RGO hybrids with rather low charge recombination and enhanced photocatalytic activity [103]. Higher photocatalytic activity is explained by the effective charge transfer from plasmon-excited Ag nanocrystal to reduced graphene oxide [104] and the reduced charge recombination during photocatalytic process. Similar to graphene hybridization effect, BN-Ag₃PO₄ composites showed higher photocatalytic activity than the pure Ag₃PO₄ due to suppression of the electron-hole pair recombination [105].

(a)

(b)

ZnO/graphene composites have also been used to increase photocatalytic efficiency [107] where the coverage of graphene on the surface of ZnO nanoparticles has been found to be crucial for higher photocatalytic activity since the enhancement of photocatalytic activity of the hybrid structure is explained by the higher separation efficiency of electron-hole pairs. Similarly, TiO₂ (P25)-graphene nanocomposite photocatalyst is shown to exhibit improved charge separation and enhanced light absorption [108]. In general, graphene in the composites is reported to act as an electron acceptor and transporter [109]. Figure 2(b) describes layered MoS₂/graphene hybrid as a high-performance photocatalyst for H₂ evolution [106]. Although this study focuses on solar H₂ generation system, the research work can be adopted to coatings technology as long as progress on large-area growth of 2D thin films continues [104, 110]. The enhanced photocatalytic activity in the case of MoS₂/graphene hybrid is attributed to the synergetic effect between the MoS₂ and graphene components acting as an electron collector and a source of active adsorption sites, respectively.

2.1.3. Techniques for Surface Modification

The methods related to surface modification include a wide range of techniques which involve surface modification of metal oxide particles before embedding them in thin films and/or alteration of metal oxide-hybridized thin film surface [72, 111–113]. We will briefly examine the advancements of such surface techniques enhancing the photocatalytic activity. The extent of electron-hole pair diffusion into interfacial charge-transfer reactions determines photocatalytic efficiency directly [114]. Such charge-transfer reactions can be increased by different surface methods such as surface derivatization [115], chemical solution deposition with metal oxides such as Fe₂O₃ and Al₂O₃ [113], complexation-chelation [116], platinization [117], grafting polymer [118], using polymeric g-C₃N₄ photocatalysts loaded with Ag nanoparticles [119], and depositing metals [120]. Adsorption of complexants is suggested to enhance the electron transfer from the conduction band to the acceptors [121]. Complexation of titanium surface ions is found to shift the redox level of Ti(IV)/Ti(III) electronic state to the conduction band avoiding electron trapping. Chelation relies on metal ions that react with organic molecules. Film derivation by using the suspension of nanoparticles takes interest due to low-temperature process enabling economic and large-area deposition. However nonuniform film surface is formed because of agglomerations [122]. Surface coverage by dyes is found to enhance optical absorption in the visible range [123]. Surface platinization of TiO₂ has been investigated in the literature [124] as the platinized TiO₂ shows high photocatalytic activity due to lower recombination rate under the presence of Pt deposits on TiO₂. It has been demonstrated that Pt provides electron trapping and enables interfacial electron transfer to acceptors [125]. Therefore, noble metals including Rh, Ni, Pt, and Pd can increase the electron transfer to O₂ and hence the quantum yield [126, 127]. Electron-hole pair separation and reduction rates are improved by depositing these catalytic metals on semiconductor catalysts [111, 120].

2.1.4. Combination of Photocatalysts

When cocatalysts are used to enhance each other’s catalytic activity, this leads to important benefits including higher photocatalytic efficiency and higher absorption of solar irradiation especially in the visible range. In the case of using composites, electron and hole transfer from one side to the other can decrease electron-hole pair recombination rate. For the TiO₂-ZnO composite example, the hole transfer occurs from the valance band of ZnO to the valance band of TiO₂ and the electron transfer occurs from the conduction band of TiO₂ to the conduction band of ZnO [128]. In this process, the narrower indirect bandgap of TiO₂ provides charge transfer to ZnO, whose conduction band is energetically equal to that of TiO₂ [42]. There are other reports showing photocatalytic synergy effect and enhanced photocatalytic activity due to charge transfer [43, 129]. Also, such higher photocatalytic activity of composites is explained by the increased electron-hole transfer between the conduction and valence bands due to the high binding energy of ZnO together with the high reactivity of TiO₂ [130]. The mechanisms of combined semiconductor systems and the obtained benefits such as higher electron-hole pair separation and holding reduction and oxidation reactions at two different reaction sites are demonstrated; when two different metal oxides establish a heterojunction, their work functions cause negatively charged carriers to transfer from the semiconductor with lower work function to the other semiconductor up to the state of thermal equilibrium [76, 131].

As an example for composite photocatalysts, g-C₃N₄/BiOBr material system is shown in Figure 3, indicating that the obtained bandgap is lower than that for the pure BiOBr and an enhanced photocatalytic activity is obtained [132].

The most extensively considered photocatalyst, TiO₂, is in the form of either anatase, rutile, or brookite where these might also be mixed [133]. In the case of using mixed forms of TiO₂, electron transfer from the conduction band of anatase to that of rutile provides higher photodegradation. The cocatalysts stimulate operational transfer of photo-induced carriers by acting as an antenna to collect the carriers and contribute to increasing the efficiency of the charge-transfer process [134].

Bandgap engineering is another important approach for improving photocatalytic activity where conduction and valance bands are modified using the elements of the composite photocatalysts [135]. Regarding this method, it particularly focuses on water splitting processes [136] but considering its potential for large-area surfaces, recent advancements are included to this review. In this respect, modified materials system is shown to have an extended absorption edge into the visible region and high mobility of holes in the valence band upon visible-light illumination [137].

2.1.5. Doping Effect

To change the properties of photocatalytic materials, doping is commonly used and doping of various elements including transition metals and nonmetals together with their effect on the photocatalytic activity has been studied [76, 138–140]. Doping is found to be useful to enhance absorption properties of the large bandgap photocatalyst materials. Among the studied transition metal ion dopants, Fe³⁺ was shown to contribute to reduction in recombination of carriers [141, 142]. In fact, there are controversial results in literature because the way that the dopant is added to the system is crucial for the operation. For example, Cr³⁺ both can have a positive effect [143] and a negative effect [144] on photocatalytic performance. Mesoporous Au/TiO₂ nanocomposites have also been found to show enhanced light absorption and relatively higher quantum efficiency resulting in superior photocatalytic efficiency [145]. Introduction of Zn and S has provided red shift of absorption edge for TiO₂-based nanomaterials [146].

In addition to metals, nonmetals are also used for the modification of the electronic structure and hence photocatalytic efficiency and absorption regime. One of the possible elements is nitrogen [147, 148], which shows effect of bandgap narrowing down behavior. Another effective material can be boron, enhancing visible-light absorption and improving photocatalytic activity [149]. Using combination of boron and nitrogen as dopants [134] also exhibits higher visible-light reactions whereas nitrogen might reduce surface charge transfer [41]. For the case of both carbon and sulphur doping, again improved photocatalytic activity under indoor daylight is observed [150, 151]. Liu et al. suggest that dopant locations and their chemical states allow for the intended surface conditions for efficient photocatalysis [76]. Figure 4 shows the possible mechanisms of nonmetal doping in TiO₂, which is found to be more beneficial than metal doping causing deterioration of surface structure due to the clusters. Although Figures 4(a)–4(e) show the possible reasons of visible-light absorption, the doping influence determining the electronic network is not totally clear.

(a)

(b)

(c)

(d)

(e)

2.1.6. Effect of Plasmonics

Plasmonic photocatalysis has been another alternative for increasing photocatalytic efficiency under visible-light irradiation [152–155]. This enhancement is explained by the excitation of localized plasmon polaritons on the surface of silver nanoparticles that provides a significant increase in the near-field intensities in the near UV supporting the photocatalytic behavior of TiO₂ [152]. The schematics in Figure 5 show that the Au nanoparticle can absorb visible light and can excite more holes and electrons when compared to TiO₂ itself [154]. The first intention of using plasmonic effect arises from the fact that the effective thickness of a TiO₂ photocatalytic layer is limited due to its opaqueness. The structures consisting of noble metal nanoparticles distributed on semiconductor photocatalysts can also behave like a Schottky junction in addition to localized surface plasmonic resonance [154, 156]. Such Schottky diode structures are found to be useful because of their contribution to charge separation and transfer performance where localized surface plasmonic resonance is important for absorption of visible light.

2.2. Methods for Enhanced Biocatalytic Efficiency

In the recent years, an increasing interest has developed towards environment-friendly paints and coatings. In this respect, enzyme-added films receive a considerable attention [31, 157]. Biocatalysts are favored in green process applications [32] due to their low chemical consumption requirements and absence of toxic byproducts. In addition, they are safe, easy to use, effective in low doses, applicable for a specific- or wide-range use, environmentally benign, and cost-effective [23]. These biocatalytic coatings are used for bioremediation applications, such as easy-cleaning [22], detoxifying, and self-decontaminating surfaces [22, 158, 159], demonstrating strong antiviral, bactericidal, and sporicidal effects [23, 160, 161]. In this review, we discuss the methods used for incorporation of enzymes into and onto surface coatings specifically for large-area applications, namely, enzyme entrapment and using nanostructures for enzyme immobilization such as nanoparticles [160], single-walled [162], and multiwalled nanotubes [163]. Figure 6 shows different methods, challenges, and effective parameters to be considered for generation of high-performance biocatalytic thin films.

Incorporation of enzymes into or onto solid materials is mostly achieved by either physical adsorption, covalent attachment, or matrix entrapment [164]. However, the relatively fragile nature of enzymes requires additional stabilization protocols before incorporation of the biocatalysts into the thin film coatings. Noncompatibility of the enzymes with hydrophobic polymers is another challenging aspect of incorporation of biocatalysts into plastic materials [157]. In this respect, nanostructured materials have been recognized as highly effective immobilization supports providing promising stabilization and performance solutions [32, 164, 165] to overcome the major catalytic, stability, leaching, and dispersibility problems in functional large-area coatings. Although the techniques for enzyme immobilization have already been exploited commonly [166], there are still critical drawbacks for practical applications including stability and catalytic functionality issues. In general, although storage stability is significantly enhanced [160, 167], the activity of biocatalyst is substantially reduced upon immobilization [161, 168]. The major challenges related to enzyme immobilization are identifying new matrix materials with suitable structural characteristics such as morphology and surface functionality and compositions as well as understanding the interactions between enzymes and the matrix to enhance the biocatalytic efficiency. Another point of consideration is the dispersibility of the enzymes in the bioreactive coatings. In other words, it is required to construct a film with uniform activity per unit area throughout the polymeric and paint composites [163, 169].

2.2.1. Polymer-Enzyme Coatings

Implementing enzymes into biocatalytic coatings requires finding a suitable matrix for immobilization, which will not compromise their activity and stability. Physical entrapment within and covalent attachment to polymer matrixes are the two strategies used for immobilization. Covalent attachment usually requires multistep protocol involving chemical modification of the enzyme. This type of immobilization may result in loading of solid matrixes with enzymes possessing unfavorable conformational changes which leads to lower activity and weaker substrate binding [168]. Physical entrapment on the other hand provides means to incorporate enzymes in polymer matrixes by retaining their native conformation [170]. Physical retention of enzymes into porous solid matrixes or films of polymers is defined as entrapment. Entrapment is considered as the easiest immobilization technique that generally results in no significant conformational alterations of the enzyme. However, this method is characterized by low enzyme loading and noticeable mass transfer limitations. Enzymes can be incorporated into functional films by mixing the biocatalysts with polymer precursors and through emulsion-polymerization procedure coating metal plates by a draw-down method [22, 171], by standard solution coating technique [31], or using a paint spreader [169, 172]. Another entrapment method is generation of sol-gel coatings. A sol is a suspension of dispersed colloids with diameters of around 1–100 nm. A rigid porous gel is generated as the sol is interconnected by cross-linking and the solution viscosity is increased by evaporation of water or alcohol in the suspension [173]. The main advantage of generating biocatalytic coatings via sol-gel entrapment is that the coatings retain a significant amount of water [170], which is crucial for enzyme structural, operational, and storage stability. In addition, sol-gel processes involve low-temperature hydrolysis of monomeric precursors and are thus highly suitable for the microencapsulation of fragile biomolecules [167].

The main problem reported for physically entrapped enzymes within a coating matrix is the decrease in biocatalytic efficiency of the film and loss of biocatalyst due to leaching upon use [174–176]. To reduce the rate and extent of leaching, one strategy is to further treat the polymer film composites with a cross-linking agent, such as glutaraldehyde, to bound the protein to the polymer network [31] or covalently immobilize the enzymes to the two-component system prior to polymerization [169]. The latter method also results in uniform distribution of enzymes within the polymer coating [169]. Another method is to produce the polymer film and then surface-attach the enzymes to the solid support via various strategies such as physical adsorption [177], covalent binding, and intermolecular cross-linking. Kim et al. (2001) investigated the effect of incorporation of proteolytic enzymes (α-chymotrypsin and pronase) into films for applications as fouling-resistant coatings [167]. They compared the effectiveness of sol-gel entrapment technique, covalent attachment of enzymes to the polydimethylsiloxane (PDMS) matrix, and direct surface attachment of the enzymes to the film. Stability-wise, the enzymatic films and paints showed higher thermal stability compared to the enzymes that are free in solution and the ones that are surface-attached to the PDMS support. However, while the covalently attached films exhibited no apparent enzyme leakage from the films, they observed that some sol-gel particles were released into solution [167, 170] during application studies.

2.2.2. Enzyme-Nanostructure Conjugate Containing Coatings

In particular, oil- and water-based paints represent cheap and readily available materials that can easily be applied to various surfaces. Incorporation of enzyme-nanostructural conjugates into these paints can create the biocatalytic surfaces with desired functional properties [167, 174]. However, the paint should not contain volatile organic solvents that could inactivate the enzyme [159, 172].

The use of nanostructural materials such as nanoparticles, nanotubes, and nanofibers, offers high surface-to-volume ratio, resulting in higher enzyme loadings and improved thermal, operational, and storage stability [21]. Moreover, addition of enzyme-nanostructural conjugates within paint matrix produces more porous composites that are not diffusionally limited, compared to polymer coatings, even at high thicknesses of 400 nm [163]. Nevertheless, the immobilization efficiency, including optimal protein loading, favorable conformation, and high activity of the enzymes, is greatly affected by the properties of a nanomaterial such as its surface chemistry, morphology, and size [168]. Table 1 summarizes different immobilization techniques applied in the generation of biocatalytic thin film coatings and points out observations regarding their performances.

Covalent attachment of listeria bacteriophage endolysin Ply500 onto functionalized silica nanoparticles and incorporation of the conjugates into a thin poly-hydroxymethyl methacrylate (pHEMA) films resulted in highly stable (95% killing efficiency after 40-day storage) and effective biocatalytic films capable of completely killing present L. innocua cells and preventing further growth at 4°C [160]. Upon continuous washing of the films, no leaching of the enzyme conjugates was observed. The study illustrates that the SNP-Ply500-containing pHEMA films are promising candidates for applications as antilisteria coatings of cold storage rooms or food processing equipment [160].

Single-walled carbon nanotubes (SWNTs) are fine structures having diameter of 1.3–2.0 nm and length of tenths of microns, hence having a very high surface area to volume ratios [162]. Incorporation of these nanostructures into the polymeric matrix offers a high surface for interaction with biocatalysts or polymer chains that comprise the film. This enhanced interaction results in profound retention of the enzymes in the biocatalytic coatings and films [162]. In addition, owing to their surface curvature, SWNTs and nanoparticles provide means for enzyme attachment by ensuring their structural and functional stability keeping them in more native-like conformation than when attached to flatter surfaces [174, 175, 179]. Enzymes bound to SWNTs or silica nanoparticles retained higher catalytic activity compared to MWNTs at similar loading [175].

Biocatalytic surfaces for large-area applications are also generated by immobilization of enzymes onto multiwalled carbon nanotubes (MWNTs) and subsequently mixing the resulting conjugates with eco-friendly paints [23, 161, 163, 176]. MWNTs are preferred support materials for enzyme immobilization due to their ease of surface functionalization, very high surface-area-to-volume ratios that afford high enzyme loading without diffusional limitations [176]. Moreover, their light weight and high mechanical strength make them excellent filling materials to reinforce polymers and ensure entrapment of the biocatalyst and thus retain the enzyme within the composite (with no enzyme leaching) [163]. However, pristine carbon nanotubes tend to aggregate in both aqueous and organic solutions due to surface-surface van der Waals interactions. This, however, reduces the available area for protein attachment as well as the nanotube dispersion within polymer matrix or paint [163]. Similar studies with carbon nanoparticles showed that aggregation of nanoparticles created agglomerates ranging from several hundred nm to several μm [168]. This agglomeration influenced enzyme loading and activity by reducing the available adsorption surface. To improve dispersibility, it has been shown that functionalization of nanotubes with flexible poly ethylene glycol (PEG) spacer arms increases nanotube dispersion in solution and prevents clumping of the nanostructures by blocking hydrophobic side walls of the carbon nanotubes [159]. Moreover, it is crucial to optimize spacer lengths, since long ones (>2000) might potentially create porous composites with altered mechanical properties [163]. In addition, oxidizing MWNT generates highly hydrophilic structures (carboxyl acid “handles” on the surface) that enables them to become water soluble/dispersible [161, 175].

2.2.3. Enzyme Loading

Enzyme-carrier materials with reduced size can generally improve the efficiency of enzyme immobilization by providing larger surface area for attachment, leading to higher protein loading per unit mass of particles [164]. The amount of enzyme molecules immobilized per unit area (i.e., protein loading) may increase or decrease the performance of biocatalytic film. For some enzymes, too much loading on the surface may restrict the spatial orientation of the protein chain, limit the accessibility of the enzyme’s active site, or denature the enzymes, thereby, reducing their activity [180]. Rather than the enzyme loading, it is critical to obtain optimum surface accessibility and functional stability for the biocatalyst, so that the reactions take place. However, it has been shown that, upon active site titration of enzyme-containing polymeric films, the observed high activity is mainly due to enzymes embedded within the polymeric coating rather than on the surface only [31].

3. Growth Techniques towards Large-Area Catalytic Coatings

Growth techniques are critical in determining size, orientation, and shape of catalytic material systems in addition to the characteristics of thin film that these particles or enzymes are embedded. Naturally crystallinity and surface features significantly affect catalytic reactions in thin films. Hence, various process methods have been used to form the thin film and the photocatalytic metal oxides and determine the crystal, surface, and electronic structure of materials, which affects bulk diffusion, surface transfer, and redox potentials [76]. Liquid based processes can be advantageous because they start forming the structures in aqueous solution and they allow for forming homogeneous films and enabling control of growth parameters and hence film properties [57]. However, for wide utilization of photocatalytic effect and to get rid of recycling problems, thin film forming needs to be performed while the photocatalytic activity is still kept at high levels. Up to now, there have been significant efforts to obtain high photocatalytic efficiency on large areas. We will present the major film formation methods in this section.

Using hydrothermal and solvo methods photocatalytic particles are crystallized at high temperature and high vapor pressure conditions, utilizing organic solvents including methanol [181] and toluene [182]. With the ability to tune synthesis conditions, grain size, morphology, and crystalline phase can be controlled. gels are treated with hydrothermal methods in mineralizing additives including fluorides, hydroxides, and chloride and also in pure water [57, 183]. TiSO₄, powder of Ti, TiCl₄, H₂, and TiO(C₂O₄) can be used to obtain TiO₂ [184] where inorganic materials are realized at low temperatures [185]. Also different from coprecipitation, this method does not need extra thermal processing. Chemical solution decomposition [186], two-step wet chemical method [187], and chemical vapor decomposition [188] techniques have also been used to obtain photocatalytic particles.

In the case of sol-gel technique, there are important advantages such as the ability to control the structure of a nanosized material starting from the first steps of the process and also homogenous coatings that can be formed at rather low temperatures [189]. These show its potential for coating large and complex areas at a relatively low cost [190] with multifunctionality [191]. The films commonly show mesoporous structures by ionic and neutral surfactants [192]. Hydrolysis and polycondensation occur during the formation of solid thin film where either alkoxide or nonalkoxide techniques can be used depending on the intended physical and chemical properties of the end products. In the case of commonly used alkoxide route, metal alkoxides are the raw materials [193] and for the nonalkoxide technique, inorganic salts are needed to be used [194]. The sol-gel method exhibits another advantage where different metals such as Ca²⁺ [195], Pb²⁺ [196], Ag⁺ [197], Fe³⁺ [198], V⁵⁺ [199], Co²⁺ [200], Au³⁺ [201], and La³⁺ [202] can be added to films to increase photocatalytic effect.

In many cases, chemical vapor deposition (CVD) is beneficial because of its versatility and fast processing abilities [203], which enables large-area processing. According to the activation method, pressure, and precursors, compounds are formed either by a chemical reaction or from decomposition of gas phase precursors [204]. Physical vapor deposition (PVD) deposits compounds physically from gas phase to coat substrate instead of chemical reactions. As thermal evaporation is the most commonly used technique in PVD systems, to realize sufficiently conductive TiO₂, it is required to heat up to 900°C in hydrogen atmosphere ambient [205].

Spray pyrolysis uses aerosol precursor solution and directs this aerosol to the target, contrary to chemical vapour deposition, which needs diffusion [206, 207]. This method is also beneficial with its low cost, high reproducibility, and speed to coat large areas with moderately good structural properties whereas uniformity is still a problem. There are some other techniques for growing metal oxide particles; although they may not be proved to be used for large-area surfaces at low cost, they are still worth being mentioned. Despite the fact that microemulsions were observed to be encouraging in early experimental works, the synthesis of controlled titania with microemulsions has not been straightforward up to date [208].

Advanced film properties of structures such as nanoporosity, epitaxial layers, superlattice, and quantum dot structures can be controlled by using electrochemical synthesis. The desired properties are obtained by altering the parameters including temperature, potential value, pH, and current density where acidic and oxygen-free environment is required for electrolysis to be successful [209]. It has been reported that overcoming this problem is possible by using nonaqueous solutions [210]. In addition to these techniques, magnetron sputtering [211] and atomic layer deposition [212] are of significance considering their potential to realize large-area films which can be structured with the desired properties.

Undoubtedly, the science, technology, and industry of large-area catalytic coatings will continue to gain importance for green applications that will find their place in different fields including architecture and automotive and environmental remediation. There is already an important progress in the last few decades and is already providing answers with growing expectations for the future.

4. Large-Area Applications of Multifunctional Catalytic Films Future Prospects

Up to present, catalytic thin films have been studied from different aspects by numerous researchers as they can be employed on surfaces with a wide range of purposes including optical, optoelectronic, magnetic, electrical, thermal, photoelectrochemical, photovoltaic, mechanical, biomedical, and catalytic applications [178, 213–217]. Figure 7 shows an integrated sol-gel produced material system exhibiting antireflectivity, water repellence, antifogging, and photocatalytic activity where the coating is proposed to be used for photovoltaic applications [178].

Obviously, high potential of catalytic coatings to combat environmental problems with widespread exploitation is of great significance. Greenhouse gasses are being released constantly and increasingly on global scale [218–220]. Hence, using smart and functional coatings provides an important alternative to this serious green gas emission problem and will make contribution to the solution of environmental pollution [221–224]. Nanotechnology obviously enhances the performance of the coatings considering the final objective of decreasing greenhouse gases by massive environmental remediation. However, it is still not straightforward to commercialize such products because of the industrial difficulties including the levels of catalytic efficiencies in the visible spectral range and economical manufacturing methods for ecological and sustainable coatings with the intended functionalities. On the other hand, as reviewed in this paper, there are numerous possible organic and/or inorganic solutions, which enhance the performance parameters to realize functional and innovative structures [225].

5. Conclusions

Considering the incrementally increasing environmental pollution and its impacts on global scale, there is substantial need for development and application of advanced, low-cost, large-scale, green solutions capable of reducing and even eliminating the pollution. In this respect, large-area catalytic thin films are highly promising for green technology applications to save energy and combat pollution and global warming. To date, organic and inorganic catalytic materials have been investigated comprehensively, considering their geometrical and electronic structures, surface reactions, synergistic behavior with other material systems, and stability issues. In general, catalysts lose their effectiveness when they are immobilized in thin films compared to the case when they operate in aqueous environment. However, there is a wide range of methods that have been reported to enhance the efficiency of these catalysts when embedded in coatings.

This review paper covers the developments of photo- and biocatalytic thin films and coatings formed using nanotechnology. Therefore, it is a subset of “catalytics and nano” focusing on formation of thin films containing catalytic nanostructures for large-area applications. The reviewed research work not only includes large-area applications that offer solutions for environmental pollution but also covers the reports that potentially can make a contribution to the low catalytic efficiency and solar spectrum absorption problem. Among these methods, hybridizing catalytic particles with other structures are attention-grabbing considering also enhancement in surface functionalities. Therefore, we gave special attention to the research studies implementing hybrid systems and, specifically, two-dimensional materials are found to be promising because of their superior properties and 2D geometries allowing for mass production capabilities.

To make use of highly appealing functionalities of these immobilized catalytic material systems, it is needed to increase the catalytic efficiency and improve the yield and feasibility. In this review, recent advancements specifically focusing on the catalytic efficiency enhancement and solar spectrum absorption are discussed. Different research reports show that the potential of nanostructuring or hybridizing methods for catalytic thin films is enthusing for the future, also providing novel applications due to enhanced functionalities. As a result, catalytic thin films will provide promising solutions to decontamination as they are embedded into systems to obtain mineralization of a variety of environmental contaminants. However, two critical challenges still remain. To begin with, significant effort continues for understanding the generic mechanisms within the matrix and interactions between the nanocatalysts and the embedded thin film system. For instance, the relationships between the biocatalyst-nanostructured carriers and the polymer matrix are to be yet investigated systematically. Such fundamental information is significantly important in the development of hybrid structures or multifunctional coatings. These fascinating challenges require interdisciplinary collaborations of material scientists, chemists, and engineers. Another impediment is the commercialization. Reducing the cost of production and demonstrating the feasibility and effectiveness of these functional coatings by long-term operation studies are the major hurdle for universalization of large-scale applications.

Conflict of Interests

The authors declare that there is no conflict of interests regarding the publication of this paper.

Acknowledgment

Nihan Kosku Perkgoz acknowledges the support from Anadolu University (BAP-1404F214 and 1407F335) for this project.

References

I. P. Parkin and R. G. Palgrave, “Self-cleaning coatings,” Journal of Materials Chemistry, vol. 15, no. 17, pp. 1689–1695, 2005.
View at: Publisher Site | Google Scholar
L. Zhao, H. Wang, K. Huo et al., “Antibacterial nano-structured titania coating incorporated with silver nanoparticles,” Biomaterials, vol. 32, no. 24, pp. 5706–5716, 2011.
View at: Publisher Site | Google Scholar
P. Roach, N. J. Shirtcliffe, and M. I. Newton, “Progess in superhydrophobic surface development,” Soft Matter, vol. 4, no. 2, pp. 224–240, 2008.
View at: Publisher Site | Google Scholar
C.-H. Xue, S.-T. Jia, J. Zhang et al., “Large-area fabrication of superhydrophobic surfaces for practical applications: an overview,” Science and Technology of Advanced Materials, vol. 11, no. 3, Article ID 033002, 2010.
View at: Publisher Site | Google Scholar
M. Gorjanc, J. Vasiljević, A. Vesel, M. Mozetic, and B. Simončič, “Plasma and sol-gel technology for creating nanostructured surfaces of fibrous polymers,” Proceedings of the International Conference. Nanomaterials: Applications and Properties, vol. 1, no. 4, 4 pages, 2012.
View at: Google Scholar
H. Ishiguro, R. Nakano, Y. Yao et al., “Photocatalytic inactivation of bacteriophages by TiO₂-coated glass plates under low-intensity, long-wavelength UV irradiation,” Photochemical and Photobiological Sciences, vol. 10, no. 11, pp. 1825–1829, 2011.
View at: Publisher Site | Google Scholar
Y. Wang, S. Jiang, M. Wang, S. Wang, T. D. Xiao, and P. R. Strutt, “Abrasive wear characteristics of plasma sprayed nanostructured alumina/titania coatings,” Wear, vol. 237, no. 2, pp. 176–185, 2000.
View at: Publisher Site | Google Scholar
A. Leyland and A. Matthews, “Design criteria for wear-resistant nanostructured and glassy-metal coatings,” Surface and Coatings Technology, vol. 177-178, pp. 317–324, 2004.
View at: Publisher Site | Google Scholar
J. Lee, S. Mahendra, and P. J. J. Alvarez, “Nanomaterials in the construction industry: a review of their applications and environmental health and safety considerations,” ACS Nano, vol. 4, no. 7, pp. 3580–3590, 2010.
View at: Publisher Site | Google Scholar
A. Steele, I. Bayer, and E. Loth, “Inherently superoleophobic nanocomposite coatings by Spray Atomization,” Nano Letters, vol. 9, no. 1, pp. 501–505, 2009.
View at: Publisher Site | Google Scholar
C. Luo, X. Zuo, L. Wang et al., “Flexible carbon nanotube-polymer composite films with high conductivity and superhydrophobicity made by solution process,” Nano Letters, vol. 8, no. 12, pp. 4454–4458, 2008.
View at: Publisher Site | Google Scholar
F. C. Krebs, H. Spanggard, T. Kjær, M. Biancardo, and J. Alstrup, “Large area plastic solar cell modules,” Materials Science and Engineering B, vol. 138, no. 2, pp. 106–111, 2007.
View at: Publisher Site | Google Scholar
M. George, “Large area optical and opto-electronic solar thin film applications,” in Optics for Solar Energy, Optical Society of America, 2010.
View at: Google Scholar
B. S. Shim, J. Zhu, E. Jan et al., “Multiparameter structural optimization of single-walled carbon nanotube composites: toward record strength, stiffness, and toughness,” ACS Nano, vol. 3, no. 7, pp. 1711–1722, 2009.
View at: Publisher Site | Google Scholar
S. Filocamo, R. Stote, D. Ziegler, and H. Gibson, “Entrapment of DFPase in titania coatings from a biomimetically derived method,” Journal of Materials Research, vol. 26, no. 8, pp. 1042–1051, 2011.
View at: Publisher Site | Google Scholar
R. Dastjerdi and M. Montazer, “A review on the application of inorganic nano-structured materials in the modification of textiles: focus on anti-microbial properties,” Colloids and Surfaces B: Biointerfaces, vol. 79, no. 1, pp. 5–18, 2010.
View at: Publisher Site | Google Scholar
K. M. L. Taylor-Pashow, J. Della Rocca, R. C. Huxford, and W. Lin, “Hybrid nanomaterials for biomedical applications,” Chemical Communications, vol. 46, no. 32, pp. 5832–5849, 2010.
View at: Publisher Site | Google Scholar
P. Gunawan, C. Guan, X. Song et al., “Hollow fiber membrane decorated with Ag/MWNTs: toward effective water disinfection and biofouling control,” ACS Nano, vol. 5, no. 12, pp. 10033–10040, 2011.
View at: Publisher Site | Google Scholar
U. Diebold, “The surface science of titanium dioxide,” Surface Science Reports, vol. 48, no. 5–8, pp. 53–229, 2003.
View at: Publisher Site | Google Scholar
A. Fujishima and X. T. Zhang, “Titanium dioxide photocatalysis: present situation and future approaches,” Comptes Rendus Chimie, vol. 9, no. 5-6, pp. 750–760, 2006.
View at: Publisher Site | Google Scholar
N. Grover, C. Z. Dinu, R. S. Kane, and J. S. Dordick, “Enzyme-based formulations for decontamination: current state and perspectives,” Applied Microbiology and Biotechnology, vol. 97, no. 8, pp. 3293–3300, 2013.
View at: Publisher Site | Google Scholar
S. Wu, A. Buthe, H. Jia, M. Zhang, M. Ishii, and P. Wang, “Enzyme-enabled responsive surfaces for anti-contamination materials,” Biotechnology and Bioengineering, vol. 110, no. 6, pp. 1805–1810, 2013.
View at: Publisher Site | Google Scholar
N. Grover, M. P. Douaisi, I. V. Borkar et al., “Perhydrolase-nanotube paint composites with sporicidal and antiviral activity,” Applied Microbiology and Biotechnology, vol. 97, no. 19, pp. 8813–8821, 2013.
View at: Publisher Site | Google Scholar
P. N. Manoudis, I. Karapanagiotis, A. Tsakalof, I. Zuburtikudis, B. Kolinkeová, and C. Panayiotou, “Superhydrophobic films for the protection of outdoor cultural heritage assets,” Applied Physics A, vol. 97, no. 2, pp. 351–360, 2009.
View at: Publisher Site | Google Scholar
A. Arora and G. W. Padua, “Review: nanocomposites in food packaging,” Journal of Food Science, vol. 75, no. 1, pp. R43–R49, 2010.
View at: Publisher Site | Google Scholar
H. N. Cheng, A. G. Richard, and B. S. Patrick, Eds., Green Polymer Chemistry: Biocatalysis and Materials II, ACS Symposium Series 1144, American Chemical Society, 2013.
M. Misson, H. Zhang, and B. Jin, “Nanobiocatalyst advancements and bioprocessing applications,” Journal of the Royal Society Interface, vol. 12, no. 102, 2015.
View at: Publisher Site | Google Scholar
K. W. Guo, “Green nanotechnology of trends in future energy: a review,” International Journal of Energy Research, vol. 36, no. 1, pp. 1–17, 2012.
View at: Publisher Site | Google Scholar
P. Tufvesson, J. Lima-Ramos, M. Nordblad, and J. M. Woodley, “Guidelines and cost analysis for catalyst production in biocatalytic processes,” Organic Process Research and Development, vol. 15, no. 1, pp. 266–274, 2011.
View at: Publisher Site | Google Scholar
“Combating climate change,” Nature Nanotechnology, vol. 2, no. 6, article 325, 2007.
View at: Publisher Site | Google Scholar
S. J. Novick and J. S. Dordick, “Protein-containing hydrophobic coatings and films,” Biomaterials, vol. 23, no. 2, pp. 441–448, 2002.
View at: Publisher Site | Google Scholar
M. Misson, H. Zhang, and B. Jin, “Nanobiocatalyst advancements and bioprocessing applications,” Journal of the Royal Society Interface, vol. 12, no. 102, Article ID 20140891, 2015.
View at: Publisher Site | Google Scholar
A. Heller, “Conversion of sunlight into electrical power and photoassisted electrolysis of water in photoelectrochemical cells,” Accounts of Chemical Research, vol. 14, no. 5, pp. 154–162, 1981.
View at: Publisher Site | Google Scholar
A. Fujishima, T. N. Rao, and D. A. Tryk, “Titanium dioxide photocatalysis,” Journal of Photochemistry and Photobiology C: Photochemistry Reviews, vol. 1, no. 1, pp. 1–21, 2000.
View at: Publisher Site | Google Scholar
M. Anpo, H. Nakaya, S. Kodama, Y. Kubokawa, K. Domen, and T. Onishi, “Photocatalysis over binary metal oxides. Enhancement of the photocatalytic activity of TiO₂ in titanium-silicon oxides,” Journal of Physical Chemistry, vol. 90, no. 8, pp. 1633–1636, 1986.
View at: Publisher Site | Google Scholar
M. Anpo and Y. Kubokawa, “Photoinduced and photocatalytic reactions on supported metal oxide catalysts. Excited states of oxides and reaction intermediates,” Reviews of Chemical Intermediates, vol. 8, no. 1, pp. 105–124, 1987.
View at: Publisher Site | Google Scholar
K. Hashimoto, H. Irie, and A. Fujishima, “TiO₂ photocatalysis: a historical overview and future prospects,” Japanese Journal of Applied Physics R, vol. 44, no. 12, pp. 8269–8285, 2005.
View at: Publisher Site | Google Scholar
P. V. Kamat, “Photophysical, photochemical and photocatalytic aspects of metal nanoparticles,” The Journal of Physical Chemistry B, vol. 106, no. 32, pp. 7729–7744, 2002.
View at: Publisher Site | Google Scholar
F. Gao, X. Chen, K. Yin et al., “Visible-light photocatalytic properties of weak magnetic BiFeO₃ nanoparticles,” Advanced Materials, vol. 19, no. 19, pp. 2889–2892, 2007.
View at: Publisher Site | Google Scholar
X. Hong, Z. Wang, W. Cai et al., “Visible-light-activated nanoparticle photocatalyst of iodine-doped titanium dioxide,” Chemistry of Materials, vol. 17, no. 6, pp. 1548–1552, 2005.
View at: Publisher Site | Google Scholar
E. Martínez-Ferrero, Y. Sakatani, C. Boissière et al., “Nanostructured titanium oxynitride porous thin films as efficient visible-active photocatalysts,” Advanced Functional Materials, vol. 17, no. 16, pp. 3348–3354, 2007.
View at: Publisher Site | Google Scholar
N. K. Perkgoz, R. S. Toru, E. Unal et al., “Photocatalytic hybrid nanocomposites of metal oxide nanoparticles enhanced towards the visible spectral range,” Applied Catalysis B: Environmental, vol. 105, no. 1-2, pp. 77–85, 2011.
View at: Publisher Site | Google Scholar
H. Y. Yang, S. F. Yu, S. P. Lau, X. Zhang, D. D. Sun, and G. Jun, “Direct growth of ZnO nanocrystals onto the surface of porous TiO₂ nanotube arrays for highly efficient and recyclable photocatalysts,” Small, vol. 5, no. 20, pp. 2260–2264, 2009.
View at: Publisher Site | Google Scholar
A. Kudo, “Photocatalyst materials for water splitting,” Catalysis Surveys from Asia, vol. 7, no. 1, pp. 31–38, 2003.
View at: Publisher Site | Google Scholar
A. Kudo and Y. Miseki, “Heterogeneous photocatalyst materials for water splitting,” Chemical Society Reviews, vol. 38, no. 1, pp. 253–278, 2009.
View at: Publisher Site | Google Scholar
G. Jiang, Z. Lin, C. Chen et al., “TiO₂ nanoparticles assembled on graphene oxide nanosheets with high photocatalytic activity for removal of pollutants,” Carbon, vol. 49, no. 8, pp. 2693–2701, 2011.
View at: Publisher Site | Google Scholar
K. Woan, G. Pyrgiotakis, and W. Sigmund, “Photocatalytic carbon-nanotube-TiO₂ composites,” Advanced Materials, vol. 21, no. 21, pp. 2233–2239, 2009.
View at: Publisher Site | Google Scholar
M. R. Hoffmann, S. T. Martin, W. Choi, and D. W. Bahnemann, “Environmental applications of semiconductor photocatalysis,” Chemical Reviews, vol. 95, no. 1, pp. 69–96, 1995.
View at: Publisher Site | Google Scholar
U. I. Gaya and A. H. Abdullah, “Heterogeneous photocatalytic degradation of organic contaminants over titanium dioxide: a review of fundamentals, progress and problems,” Journal of Photochemistry and Photobiology C: Photochemistry Reviews, vol. 9, no. 1, pp. 1–12, 2008.
View at: Publisher Site | Google Scholar
R. Cai, K. Hashimoto, K. Itoh, Y. Kubota, and A. Fujishima, “Photokilling of malignant cells with ultrafine TiO₂ powder,” Bulletin of the Chemical Society of Japan, vol. 64, no. 4, pp. 1268–1273, 1991.
View at: Publisher Site | Google Scholar
T. Matsunaga, R. Tomoda, T. Nakajima, and H. Wake, “Photoelectrochemical sterilization of microbial cells by semiconductor powders,” FEMS Microbiology Letters, vol. 29, no. 1-2, pp. 211–214, 1985.
View at: Publisher Site | Google Scholar
N.-G. Park, J. Van de Lagemaat, and A. J. Frank, “Comparison of dye-sensitized rutile- and anatase-based TiO₂ solar cells,” The Journal of Physical Chemistry B, vol. 104, no. 38, pp. 8989–8994, 2000.
View at: Google Scholar
Y.-C. Kim, S. Sasaki, K. Yano, K. Ikebukuro, K. Hashimoto, and I. Karube, “Photocatalytic sensor for the determination of chemical oxygen demand using flow injection analysis,” Analytica Chimica Acta, vol. 432, no. 1, pp. 59–66, 2001.
View at: Publisher Site | Google Scholar
M. Grätzel, “Photoelectrochemical cells,” Nature, vol. 414, no. 6861, pp. 338–344, 2001.
View at: Publisher Site | Google Scholar
G. Palmisano, M. C. Gutiérrez, M. L. Ferrer et al., “TiO₂/ORMOSIL thin films doped with phthalocyanine dyes: new photocatalytic devices activated by solar light,” Journal of Physical Chemistry C, vol. 112, no. 7, pp. 2667–2670, 2008.
View at: Publisher Site | Google Scholar
L. Vayssieres, “Advanced semiconductor nanostructures,” Comptes Rendus Chimie, vol. 9, no. 5-6, pp. 691–701, 2006.
View at: Publisher Site | Google Scholar
O. Carp, C. L. Huisman, and A. Reller, “Photoinduced reactivity of titanium dioxide,” Progress in Solid State Chemistry, vol. 32, no. 1-2, pp. 33–177, 2004.
View at: Publisher Site | Google Scholar
S. Sarkar, R. Das, H. Choi, and C. Bhattacharjee, “Involvement of process parameters and various modes of application of TiO₂ nanoparticles in heterogeneous photocatalysis of pharmaceutical wastes—a short review,” RSC Advances, vol. 4, no. 100, pp. 57250–57266, 2014.
View at: Publisher Site | Google Scholar
Z. Tong, Y. Jiang, D. Yang et al., “Biomimetic and bioinspired synthesis of titania and titania-based materials,” RSC Advances, vol. 4, no. 24, pp. 12388–12403, 2014.
View at: Publisher Site | Google Scholar
D. F. Ollis, “Photocatalytic purification and remediation of contaminated air and water,” Comptes Rendus de l'Académie des Sciences Series IIC: Chemistry, vol. 3, no. 6, pp. 405–411, 2000.
View at: Publisher Site | Google Scholar
S. Ahmed, M. G. Rasul, W. N. Martens, R. Brown, and M. A. Hashib, “Advances in heterogeneous photocatalytic degradation of phenols and dyes in wastewater: a review,” Water, Air, & Soil Pollution, vol. 215, no. 1–4, pp. 3–29, 2011.
View at: Publisher Site | Google Scholar
J. C. Sjogren and R. A. Sierka, “Inactivation of phage MS2 by iron-aided titanium dioxide photocatalysis,” Applied and Environmental Microbiology, vol. 60, no. 1, pp. 344–347, 1994.
View at: Google Scholar
S. Banerjee, J. Gopal, P. Muraleedharan, A. K. Tyagi, and B. Raj, “Physics and chemistry of photocatalytic titanium dioxide: visualization of bactericidal activity using atomic force microscopy,” Current Science, vol. 90, no. 10, pp. 1378–1383, 2006.
View at: Google Scholar
K. Kabra, R. Chaudhary, and R. L. Sawhney, “Treatment of hazardous organic and inorganic compounds through aqueous-phase photocatalysis: a review,” Industrial & Engineering Chemistry Research, vol. 43, no. 24, pp. 7683–7696, 2004.
View at: Publisher Site | Google Scholar
F. A. Harraz, O. E. Abdel-Salam, A. A. Mostafa, R. M. Mohamed, and M. Hanafy, “Rapid synthesis of titania-silica nanoparticles photocatalyst by a modified sol-gel method for cyanide degradation and heavy metals removal,” Journal of Alloys and Compounds, vol. 551, 7 pages, 2013.
View at: Publisher Site | Google Scholar
L. Obalová, M. Reli, J. Lang et al., “Photocatalytic decomposition of nitrous oxide using TiO₂ and Ag-TiO₂ nanocomposite thin films,” Catalysis Today, vol. 209, pp. 170–175, 2013.
View at: Publisher Site | Google Scholar
T. Kimura, N. Yoshikawa, N. Matsumura, and Y. Kawase, “Photocatalytic degradation of nonionic surfactants with immobilized TiO₂ in an airlift reactor,” Journal of Environmental Science and Health A-Toxic/Hazardous Substances and Environmental Engineering, vol. 39, no. 11-12, pp. 2867–2881, 2004.
View at: Publisher Site | Google Scholar
A. Rachel, M. Subrahmanyam, and P. Boule, “Comparison of photocatalytic efficiencies of TiO₂ in suspended and immobilised form for the photocatalytic degradation of nitrobenzenesulfonic acids,” Applied Catalysis B: Environmental, vol. 37, no. 4, pp. 301–308, 2002.
View at: Publisher Site | Google Scholar
B. Ohtani, “Titania photocatalysis beyond recombination: a critical review,” Catalysts, vol. 3, no. 4, pp. 942–953, 2013.
View at: Publisher Site | Google Scholar
H. D. Jang, S.-K. Kim, and S.-J. Kim, “Effect of particle size and phase composition of titanium dioxide nanoparticles on the photocatalytic properties,” Journal of Nanoparticle Research, vol. 3, no. 2-3, pp. 141–147, 2001.
View at: Publisher Site | Google Scholar
H. Zhou, Y. Qu, T. Zeid, and X. Duan, “Towards highly efficient photocatalysts using semiconductor nanoarchitectures,” Energy & Environmental Science, vol. 5, no. 5, pp. 6732–6743, 2012.
View at: Publisher Site | Google Scholar
S. G. Kumar and L. G. Devi, “Review on modified TiO₂ photocatalysis under UV/visible light: Selected results and related mechanisms on interfacial charge carrier transfer dynamics,” Journal of Physical Chemistry A, vol. 115, no. 46, pp. 13211–13241, 2011.
View at: Publisher Site | Google Scholar
N. Wu, J. Wang, D. N. Tafen et al., “Shape-enhanced photocatalytic activity of single-crystalline anatase TiO₂ (101) nanobelts,” Journal of the American Chemical Society, vol. 132, no. 19, pp. 6679–6685, 2010.
View at: Publisher Site | Google Scholar
D. Beydoun, R. Amal, G. Low, and S. McEvoy, “Role of nanoparticles in photocatalysis,” Journal of Nanoparticle Research, vol. 1, no. 4, pp. 439–458, 1999.
View at: Publisher Site | Google Scholar
L. Zhang, H. Yang, J. Yu et al., “Controlled synthesis and photocatalytic activity of ZnSe nanostructured assemblies with different morphologies and crystalline phases,” The Journal of Physical Chemistry C, vol. 113, no. 14, pp. 5434–5443, 2009.
View at: Publisher Site | Google Scholar
G. Liu, L. Wang, H. G. Yang, H.-M. Cheng, and G. Q. Lu, “Titania-based photocatalysts-crystal growth, doping and heterostructuring,” Journal of Materials Chemistry, vol. 20, no. 5, pp. 831–843, 2010.
View at: Publisher Site | Google Scholar
L. Guo, D. Jing, M. Liu et al., “Functionalized nanostructures for enhanced photocatalytic performance under solar light,” Beilstein Journal of Nanotechnology, vol. 5, no. 1, pp. 994–1004, 2014.
View at: Publisher Site | Google Scholar
I. M. Arabatzis, S. Antonaraki, T. Stergiopoulos et al., “Preparation, characterization and photocatalytic activity of nanocrystalline thin film TiO₂ catalysts towards 3,5-dichlorophenol degradation,” Journal of Photochemistry and Photobiology A: Chemistry, vol. 149, no. 1–3, pp. 237–245, 2002.
View at: Publisher Site | Google Scholar
A. Fernández, G. Lassaletta, V. M. Jiménez et al., “Preparation and characterization of TiO₂ photocatalysts supported on various rigid supports (glass, quartz and stainless steel). Comparative studies of photocatalytic activity in water purification,” Applied Catalysis B, Environmental, vol. 7, no. 1-2, pp. 49–63, 1995.
View at: Publisher Site | Google Scholar
R. L. Pozzo, M. A. Baltanás, and A. E. Cassano, “Towards a precise assessment of the performance of supported photocatalysts for water detoxification processes,” Catalysis Today, vol. 54, no. 1, pp. 143–157, 1999.
View at: Publisher Site | Google Scholar
H. Tong, S. Ouyang, Y. Bi, N. Umezawa, M. Oshikiri, and J. Ye, “Nano-photocatalytic materials: possibilities and challenges,” Advanced Materials, vol. 24, no. 2, pp. 229–251, 2012.
View at: Publisher Site | Google Scholar
R. Comparelli, P. D. Cozzoli, M. L. Curri, A. Agostiano, G. Mascolo, and G. Lovecchio, “Photocatalytic degradation of methyl-red by immobilised nanoparticles of TiO₂ and ZnO,” Water Science and Technology, vol. 49, no. 4, pp. 183–188, 2004.
View at: Google Scholar
A. Henglein, “Nanoclusters of semiconductors and metals: colloidal nano-particles of semiconductors and metals: electronic structure and processes,” Berichte der Bunsengesellschaft für physikalische Chemie, vol. 101, no. 11, pp. 1562–1572, 1997.
View at: Google Scholar
V. Subramanian, E. Wolf, and P. V. Kamat, “Semiconductor-metal composite nanostructures. To what extent do metal nanoparticles improve the photocatalytic activity of TiO₂ films?” Journal of Physical Chemistry B, vol. 105, no. 46, pp. 11439–11446, 2001.
View at: Publisher Site | Google Scholar
A. Henglein, “Mechanism of reactions on colloidal microelectrodes and size quantization effects,” in Electrochemistry II, vol. 143 of Topics in Current Chemistry, pp. 113–180, Springer, Berlin, Germany, 1988.
View at: Publisher Site | Google Scholar
A. Henglein, “Small-particle research: physicochemical properties of extremely small colloidal metal and semiconductor particles,” Chemical Reviews, vol. 89, no. 8, pp. 1861–1873, 1989.
View at: Publisher Site | Google Scholar
D. W. Bahnemann, “Ultrasmall metal oxide particles: preparation, photophysical characterization, and photocatalytic properties,” Israel Journal of Chemistry, vol. 33, no. 1, pp. 115–136, 1993.
View at: Publisher Site | Google Scholar
H. Weller and A. Eychmüller, “Photochemistry and photoelectrochemistry of quantized matter: properties of semiconductor nanoparticles in solution and thin-film electrodes,” in Advances in Photochemistry, vol. 20, chapter 4, pp. 165–216, John Wiley & Sons, 2007.
View at: Publisher Site | Google Scholar
A. Hagfeld and M. Grätzel, “Light-induced redox reactions in nanocrystalline systems,” Chemical Reviews, vol. 95, no. 1, pp. 49–68, 1995.
View at: Publisher Site | Google Scholar
A. J. Hoffman, G. Mills, H. Yee, and M. R. Hoffmann, “Q-sized cadmium sulfide: synthesis, characterization, and efficiency of photoinitiation of polymerization of several vinylic monomers,” The Journal of Physical Chemistry, vol. 96, no. 13, pp. 5546–5552, 1992.
View at: Publisher Site | Google Scholar
P. V. Kamat, “Tailoring nanostructured thin-films,” Chemtech, vol. 25, no. 6, pp. 22–28, 1995.
View at: Google Scholar
Y. Li, T. Kunitake, and S. Fujikawa, “Efficient fabrication and enhanced photocatalytic activities of 3D-ordered films of titania hollow spheres,” The Journal of Physical Chemistry B, vol. 110, no. 26, pp. 13000–13004, 2006.
View at: Publisher Site | Google Scholar
A. O. Ibhadon and P. Fitzpatrick, “Heterogeneous photocatalysis: recent advances and applications,” Catalysts, vol. 3, no. 1, pp. 189–218, 2013.
View at: Publisher Site | Google Scholar
G. Rothenberger, J. Moser, M. Grätzel, N. Serpone, and D. K. Sharma, “Charge carrier trapping and recombination dynamics in small semiconductor particles,” Journal of the American Chemical Society, vol. 107, no. 26, pp. 8054–8059, 1985.
View at: Publisher Site | Google Scholar
S. Deng, S. W. Verbruggen, Z. He et al., “Atomic layer deposition-based synthesis of photoactive TiO₂ nanoparticle chains by using carbon nanotubes as sacrificial templates,” RSC Advances, vol. 4, no. 23, pp. 11648–11653, 2014.
View at: Publisher Site | Google Scholar
Y. Liang, H. S. Wang, H. S. Casalongue, Z. Chen, and H. Dai, “TiO₂ nanocrystals grown on graphene as advanced photocatalytic hybrid materials,” Nano Research, vol. 3, no. 10, pp. 701–705, 2010.
View at: Publisher Site | Google Scholar
Z. Wang, J. Sha, E. Liu et al., “A large ultrathin anatase TiO₂ nanosheet/reduced graphene oxide composite with enhanced lithium storage capability,” Journal of Materials Chemistry A, vol. 2, no. 23, pp. 8893–8901, 2014.
View at: Publisher Site | Google Scholar
Q. Li, B. Guo, J. Yu et al., “Highly efficient visible-light-driven photocatalytic hydrogen production of CdS-cluster-decorated graphene nanosheets,” Journal of the American Chemical Society, vol. 133, no. 28, pp. 10878–10884, 2011.
View at: Publisher Site | Google Scholar
X. Song and L. Gao, “Fabrication of hollow hybrid microspheres coated with silica/titania via sol-gel process and enhanced photocatalytic activities,” The Journal of Physical Chemistry C, vol. 111, no. 23, pp. 8180–8187, 2007.
View at: Publisher Site | Google Scholar
X. Shen, L. Zhu, J. Li, and H. Tang, “Synthesis of molecular imprinted polymer coated photocatalysts with high selectivity,” Chemical Communications, no. 11, pp. 1163–1165, 2007.
View at: Publisher Site | Google Scholar
S. Xuan, W. Jiang, X. Gong, Y. Hu, and Z. Chen, “Magnetically separable Fe₃O₄/TiO₂ hollow spheres: fabrication and photocatalytic activity,” The Journal of Physical Chemistry C, vol. 113, no. 2, pp. 553–558, 2009.
View at: Publisher Site | Google Scholar
M. Dahl, Y. Liu, and Y. Yin, “Composite titanium dioxide nanomaterials,” Chemical Reviews, vol. 114, no. 19, pp. 9853–9889, 2014.
View at: Publisher Site | Google Scholar
H. Zhang, X. Fan, X. Quan, S. Chen, and H. Yu, “Graphene sheets grafted Ag@AgCl hybrid with enhanced plasmonic photocatalytic activity under visible light,” Environmental Science & Technology, vol. 45, no. 13, pp. 5731–5736, 2011.
View at: Publisher Site | Google Scholar
X. Li, W. Cai, J. An et al., “Large-area synthesis of high-quality and uniform graphene films on copper foils,” Science, vol. 324, no. 5932, pp. 1312–1314, 2009.
View at: Publisher Site | Google Scholar
Y. Song, H. Xu, C. Wang et al., “Graphene-analogue boron nitride/Ag₃PO₄ composite for efficient visible-light-driven photocatalysis,” RSC Advances, vol. 4, no. 100, pp. 56853–56862, 2014.
View at: Publisher Site | Google Scholar
Q. Xiang, J. Yu, and M. Jaroniec, “Synergetic effect of MoS₂ and graphene as cocatalysts for enhanced photocatalytic H₂ production activity of TiO₂ nanoparticles,” Journal of the American Chemical Society, vol. 134, no. 15, pp. 6575–6578, 2012.
View at: Publisher Site | Google Scholar
T. Xu, L. Zhang, H. Cheng, and Y. Zhu, “Significantly enhanced photocatalytic performance of ZnO via graphene hybridization and the mechanism study,” Applied Catalysis B: Environmental, vol. 101, no. 3-4, pp. 382–387, 2011.
View at: Publisher Site | Google Scholar
H. Zhang, X. Lv, Y. Li, Y. Wang, and J. Li, “P25-graphene composite as a high performance photocatalyst,” ACS Nano, vol. 4, no. 1, pp. 380–386, 2010.
View at: Publisher Site | Google Scholar
Q. Liu, Z. Liu, X. Zhang et al., “Polymer photovoltaic cells based on solution-processable graphene and P3HT,” Advanced Functional Materials, vol. 19, no. 6, pp. 894–904, 2009.
View at: Publisher Site | Google Scholar
K.-K. Liu, W. Zhang, Y.-H. Lee et al., “Growth of large-area and highly crystalline MoS₂ thin layers on insulating substrates,” Nano Letters, vol. 12, no. 3, pp. 1538–1544, 2012.
View at: Publisher Site | Google Scholar
A. L. Linsebigler, G. Lu, and J. T. Yates Jr., “Photocatalysis on TiO₂ surfaces: principles, mechanisms, and selected results,” Chemical Reviews, vol. 95, no. 3, pp. 735–758, 1995.
View at: Publisher Site | Google Scholar
C. Minero, “Surface-modified photocatalysts,” 2013.
View at: Google Scholar
T. K. Kim, M. N. Lee, S. H. Lee, Y. C. Park, C. K. Jung, and J.-H. Boo, “Development of surface coating technology of TiO₂ powder and improvement of photocatalytic activity by surface modification,” Thin Solid Films, vol. 475, no. 1-2, pp. 171–177, 2005.
View at: Publisher Site | Google Scholar
W. Y. Choi, A. Termin, and M. R. Hoffmann, “The role of metal ion dopants in quantum-sized TiO₂: correlation between photoreactivity and charge carrier recombination dynamics,” Journal of Physical Chemistry, vol. 98, no. 51, pp. 13669–13679, 1994.
View at: Publisher Site | Google Scholar
A. P. Hong, D. W. Bahnemann, and M. R. Hoffmann, “Cobalt(II) tetrasulfophthalocyanine on titanium dioxide: a new efficient electron relay for the photocatalytic formation and depletion of hydrogen peroxide in aqueous suspensions,” The Journal of Physical Chemistry, vol. 91, no. 8, pp. 2109–2117, 1987.
View at: Publisher Site | Google Scholar
J. Moser, S. Punchihewa, P. P. Infelta, and M. Graetzel, “Surface complexation of colloidal semiconductors strongly enhances interfacial electron-transfer rates,” Langmuir, vol. 7, no. 12, pp. 3012–3018, 1991.
View at: Publisher Site | Google Scholar
D. W. Bahnemann, J. Moenig, and R. Chapman, “Efficient photocatalysis of the irreversible one-electron and two-electron reduction of halothane on platinized colloidal titanium dioxide in aqueous suspension,” The Journal of Physical Chemistry, vol. 91, no. 14, pp. 3782–3788, 1987.
View at: Publisher Site | Google Scholar
R. Y. Hong, J. H. Li, L. L. Chen et al., “Synthesis, surface modification and photocatalytic property of ZnO nanoparticles,” Powder Technology, vol. 189, no. 3, pp. 426–432, 2009.
View at: Publisher Site | Google Scholar
L. Ge, C. Han, J. Liu, and Y. Li, “Enhanced visible light photocatalytic activity of novel polymeric g-C₃N₄ loaded with Ag nanoparticles,” Applied Catalysis A: General, vol. 409-410, pp. 215–222, 2011.
View at: Publisher Site | Google Scholar
A. Sclafani and J.-M. Herrmann, “Influence of metallic silver and of platinum-silver bimetallic deposits on the photocatalytic activity of titania (anatase and rutile) in organic and aqueous media,” Journal of Photochemistry and Photobiology A: Chemistry, vol. 113, no. 2, pp. 181–188, 1998.
View at: Publisher Site | Google Scholar
H. Frei, D. J. Fitzmaurice, and M. Graetzel, “Surface chelation of semiconductors and interfacial electron transfer,” Langmuir, vol. 6, no. 1, pp. 198–206, 1990.
View at: Publisher Site | Google Scholar
S. Y. Chae, M. K. Park, S. K. Lee, T. Y. Kim, S. K. Kim, and W. I. Lee, “Preparation of size-controlled TiO₂ nanoparticles and derivation of optically transparent photocatalytic films,” Chemistry of Materials, vol. 15, no. 17, pp. 3326–3331, 2003.
View at: Publisher Site | Google Scholar
J. Hodak, C. Quinteros, M. I. Litter et al., “Sensitization of TiO₂ with phthalocyanines. 1. Photo-oxidations using hydroxoaluminium tricarboxymonoamidephthalocyanine adsorbed on TiO₂,” Journal of the Chemical Society-Faraday Transactions, vol. 92, no. 24, pp. 5081–5088, 1996.
View at: Publisher Site | Google Scholar
J. S. Lee and W. Y. Choi, “Photocatalytic reactivity of surface platinized TiO₂: substrate specificity and the effect of Pt oxidation state,” Journal of Physical Chemistry B, vol. 109, no. 15, pp. 7399–7406, 2005.
View at: Publisher Site | Google Scholar
U. Siemon, D. Bahnemann, J. J. Testa, D. Rodríguez, M. I. Litter, and N. Bruno, “Heterogeneous photocatalytic reactions comparing TiO₂ and Pt/TiO₂,” Journal of Photochemistry and Photobiology A: Chemistry, vol. 148, no. 1–3, pp. 247–255, 2002.
View at: Publisher Site | Google Scholar
S. Sakthivel, M. V. Shankar, M. Palanichamy, B. Arabindoo, D. W. Bahnemann, and V. Murugesan, “Enhancement of photocatalytic activity by metal deposition: characterisation and photonic efficiency of Pt, Au and Pd deposited on TiO₂ catalyst,” Water Research, vol. 38, no. 13, pp. 3001–3008, 2004.
View at: Publisher Site | Google Scholar
J. Papp, H.-S. Shen, R. Kershaw, K. Dwight, and A. Wold, “Titanium(IV) oxide photocatalysts with palladium,” Chemistry of Materials, vol. 5, no. 3, pp. 284–288, 1993.
View at: Publisher Site | Google Scholar
G. Marcì, V. Augugliaro, M. J. López-Muñoz et al., “Preparation characterization and photocatalytic activity of polycrystalline ZnO/TiO₂ systems. 2. Surface, bulk characterization, and 4-nitrophenol photodegradation in liquid-solid regime,” The Journal of Physical Chemistry B, vol. 105, no. 5, pp. 1033–1040, 2001.
View at: Google Scholar
S. Janitabar-Darzi and A. R. Mahjoub, “Investigation of phase transformations and photocatalytic properties of sol-gel prepared nanostructured ZnO/TiO₂ composites,” Journal of Alloys and Compounds, vol. 486, no. 1-2, pp. 805–808, 2009.
View at: Publisher Site | Google Scholar
M. Pelaez, N. T. Nolan, S. C. Pillai et al., “A review on the visible light active titanium dioxide photocatalysts for environmental applications,” Applied Catalysis B: Environmental, vol. 125, pp. 331–349, 2012.
View at: Publisher Site | Google Scholar
V. Etacheri, G. Michlits, M. K. Seery et al., “A highly efficient TiO_2−xC_x nano-heterojunction photocatalyst for visible light induced antibacterial applications,” ACS Applied Materials & Interfaces, vol. 5, no. 5, pp. 1663–1672, 2013.
View at: Google Scholar
J. Di, J. Xia, S. Yin et al., “A g-C₃N₄/BiOBr visible-light-driven composite: synthesis via a reactable ionic liquid and improved photocatalytic activity,” RSC Advances, vol. 3, no. 42, pp. 19624–19631, 2013.
View at: Publisher Site | Google Scholar
T. Kawahara, Y. Konishi, H. Tada, N. Tohge, J. Nishii, and S. Ito, “A patterned TiO₂(anatase)/TiO₂(rutile) bilayer-type photocatalyst: effect of the anatase/rutile junction on the photocatalytic activity,” Angewandte Chemie, vol. 41, no. 15, pp. 2811–2813, 2002.
View at: Publisher Site | Google Scholar
G. Liu, Y. Zhao, C. Sun, F. Li, G. Q. Lu, and H.-M. Cheng, “Synergistic effects of B/N doping on the visible-light photocatalytic activity of mesoporous TiO₂,” Angewandte Chemie International Edition, vol. 47, no. 24, pp. 4516–4520, 2008.
View at: Publisher Site | Google Scholar
W. Y. Teoh, J. A. Scott, and R. Amal, “Progress in heterogeneous photocatalysis: from classical radical chemistry to engineering nanomaterials and solar reactors,” The Journal of Physical Chemistry Letters, vol. 3, no. 5, pp. 629–639, 2012.
View at: Publisher Site | Google Scholar
K. Maeda and K. Domen, “Photocatalytic water splitting: recent progress and future challenges,” The Journal of Physical Chemistry Letters, vol. 1, no. 18, pp. 2655–2661, 2010.
View at: Publisher Site | Google Scholar
S. Anandan, N. Ohashi, and M. Miyauchi, “ZnO-based visible-light photocatalyst: band-gap engineering and multi-electron reduction by co-catalyst,” Applied Catalysis B: Environmental, vol. 100, no. 3-4, pp. 502–509, 2010.
View at: Publisher Site | Google Scholar
J. A. Navio, F. J. Marchena, M. Roncel et al., “A laser flash-photolysis study of the reduction of methyl viologen by conduction-band electrons of TiO₂ and Fe-Ti oxide photocatalysts,” Journal of Photochemistry and Photobiology A—Chemistry, vol. 55, no. 3, pp. 319–322, 1991.
View at: Publisher Site | Google Scholar
D. Dvoranová, V. Brezová, M. Mazúr, and M. A. Malati, “Investigations of metal-doped titanium dioxide photocatalysts,” Applied Catalysis B: Environmental, vol. 37, no. 2, pp. 91–105, 2002.
View at: Publisher Site | Google Scholar
A.-W. Xu, Y. Gao, and H.-Q. Liu, “The preparation, characterization, and their photocatalytic activities of rare-earth-doped TiO₂ nanoparticles,” Journal of Catalysis, vol. 207, no. 2, pp. 151–157, 2002.
View at: Publisher Site | Google Scholar
P. Yang, C. Lu, N. Hua, and Y. Du, “Titanium dioxide nanoparticles co-doped with Fe³⁺ and Eu³⁺ ions for photocatalysis,” Materials Letters, vol. 57, no. 4, pp. 794–801, 2002.
View at: Publisher Site | Google Scholar
C.-Y. Wang, C. Böttcher, D. W. Bahnemann, and J. K. Dohrmann, “A comparative study of nanometer sized Fe(III)-doped TiO₂ photocatalysts: synthesis, characterization and activity,” Journal of Materials Chemistry, vol. 13, no. 9, pp. 2322–2329, 2003.
View at: Publisher Site | Google Scholar
K. Palmisano, V. Augugliaro, A. Sclafani, and M. Schiavello, “Activity of chromium-ion-doped titania for the dinitrogen photoreduction to ammonia and for the phenol photodegradation,” Journal of physical chemistry, vol. 92, no. 23, pp. 6710–6713, 1988.
View at: Publisher Site | Google Scholar
W. Mu, J.-M. Herrmann, and P. Pichat, “Room temperature photocatalytic oxidation of liquid cyclohexane into cyclohexanone over neat and modified TiO₂,” Catalysis Letters, vol. 3, no. 1, pp. 73–84, 1989.
View at: Publisher Site | Google Scholar
H. Li, Z. Bian, J. Zhu, Y. Huo, H. Li, and Y. Lu, “Mesoporous Au/TiO₂ nanocomposites with enhanced photocatalytic activity,” Journal of the American Chemical Society, vol. 129, no. 15, pp. 4538–4539, 2007.
View at: Publisher Site | Google Scholar
Q. Xu, X. Wang, X. Dong, C. Ma, X. Zhang, and H. Ma, “Improved visible light photocatalytic activity for TiO₂ nanomaterials by codoping with zinc and sulfur,” Journal of Nanomaterials, vol. 2015, Article ID 157383, 8 pages, 2015.
View at: Publisher Site | Google Scholar
R. Asahi, T. Morikawa, T. Ohwaki, K. Aoki, and Y. Taga, “Visible-light photocatalysis in nitrogen-doped titanium oxides,” Science, vol. 293, no. 5528, pp. 269–271, 2001.
View at: Publisher Site | Google Scholar
X. Zhang, J. Zhou, Y. Gu et al., “Visible-light photocatalytic activity of N-doped TiO₂ nanotube arrays on acephate degradation,” Journal of Nanomaterials, vol. 2015, Article ID 527070, 6 pages, 2015.
View at: Publisher Site | Google Scholar
S. In, A. Orlov, R. Berg et al., “Effective visible light-activated B-doped and B,N-codoped TiO₂ photocatalysts,” Journal of the American Chemical Society, vol. 129, no. 45, pp. 13790–13791, 2007.
View at: Publisher Site | Google Scholar
S. Sakthivel and H. Kisch, “Daylight photocatalysis by carbon-modified titanium dioxide,” Angewandte Chemie—International Edition, vol. 42, no. 40, pp. 4908–4911, 2003.
View at: Publisher Site | Google Scholar
W. K. Ho, J. C. Yu, and S. C. Lee, “Low-temperature hydrothermal synthesis of S-doped TiO₂ with visible light photocatalytic activity,” Journal of Solid State Chemistry, vol. 179, no. 4, pp. 1171–1176, 2006.
View at: Publisher Site | Google Scholar
K. Awazu, M. Fujimaki, C. Rockstuhl et al., “A plasmonic photocatalyst consisting of silver nanoparticles embedded in titanium dioxide,” Journal of the American Chemical Society, vol. 130, no. 5, pp. 1676–1680, 2008.
View at: Publisher Site | Google Scholar
P. Wang, B. Huang, X. Zhang et al., “Highly efficient visible-light plasmonic photocatalyst Ag@AgBr,” Chemistry, vol. 15, no. 8, pp. 1821–1824, 2009.
View at: Publisher Site | Google Scholar
X. Zhang, Y. L. Chen, R.-S. Liu, and D. P. Tsai, “Plasmonic photocatalysis,” Reports on Progress in Physics, vol. 76, no. 4, Article ID 046401, 2013.
View at: Publisher Site | Google Scholar
J. Jiang, H. Li, and L. Zhang, “New insight into daylight photocatalysis of AgBr@Ag: synergistic effect between semiconductor photocatalysis and plasmonic photocatalysis,” Chemistry—A European Journal, vol. 18, no. 20, pp. 6360–6369, 2012.
View at: Publisher Site | Google Scholar
F. Pincella, K. Isozaki, and K. Miki, “A visible light-driven plasmonic photocatalyst,” Light: Science & Applications, vol. 3, no. 1, article e133, 2014.
View at: Publisher Site | Google Scholar
X. D. Tong, A. Trivedi, H. F. Jia, M. Zhang, and P. Wang, “Enzymic thin film coatings for bioactive materials,” Biotechnology Progress, vol. 24, no. 3, pp. 714–719, 2008.
View at: Publisher Site | Google Scholar
D. Han, S. Filocamo, R. Kirby, and A. J. Steckl, “Deactivating chemical agents using enzyme-coated nanofibers formed by electrospinning,” ACS Applied Materials & Interfaces, vol. 3, no. 12, pp. 4633–4639, 2011.
View at: Publisher Site | Google Scholar
I. V. Borkar, C. Z. Dinu, G. Y. Zhu, R. S. Kane, and J. S. Dordick, “Bionanoconjugate-based composites for decontamination of nerve agents,” Biotechnology Progress, vol. 26, no. 6, pp. 1622–1628, 2010.
View at: Publisher Site | Google Scholar
K. Solanki, N. Grover, P. Downs et al., “Enzyme-based listericidal nanocomposites,” Scientific Reports, vol. 3, article 1584, 2013.
View at: Publisher Site | Google Scholar
N. Grover, I. V. Borkar, C. Z. Dinu, R. S. Kane, and J. S. Dordick, “Laccase- and chloroperoxidase-nanotube paint composites with bactericidal and sporicidal activity,” Enzyme and Microbial Technology, vol. 50, no. 6-7, pp. 271–279, 2012.
View at: Publisher Site | Google Scholar
K. Rege, N. R. Raravikar, D.-Y. Kim, L. S. Schadler, P. M. Ajayan, and J. S. Dordick, “Enzyme-polymer-single walled carbon nanotube composites as biocatalytic films,” Nano Letters, vol. 3, no. 6, pp. 829–832, 2003.
View at: Publisher Site | Google Scholar
C. Z. Dinu, G. Zhu, S. S. Bale et al., “Enzyme-based nanoscale composites for use as active decontamination surfaces,” Advanced Functional Materials, vol. 20, no. 3, pp. 392–398, 2010.
View at: Publisher Site | Google Scholar
J. Kim, J. W. Grate, and P. Wang, “Nanostructures for enzyme stabilization,” Chemical Engineering Science, vol. 61, no. 3, pp. 1017–1026, 2006.
View at: Publisher Site | Google Scholar
J. Ge, D. N. Lu, Z. X. Liu, and Z. Liu, “Recent advances in nanostructured biocatalysts,” Biochemical Engineering Journal, vol. 44, no. 1, pp. 53–59, 2009.
View at: Publisher Site | Google Scholar
C. Mateo, J. M. Palomo, G. Fernandez-Lorente, J. M. Guisan, and R. Fernandez-Lafuente, “Improvement of enzyme activity, stability and selectivity via immobilization techniques,” Enzyme and Microbial Technology, vol. 40, no. 6, pp. 1451–1463, 2007.
View at: Publisher Site | Google Scholar
Y. D. Kim, J. S. Dordick, and D. S. Clark, “Siloxane-based biocatalytic films and paints for use as reactive coatings,” Biotechnology and Bioengineering, vol. 72, no. 4, pp. 475–482, 2001.
View at: Publisher Site | Google Scholar
R. Pang, M. Z. Li, and C. D. Zhang, “Degradation of phenolic compounds by laccase immobilized on carbon nanomaterials: diffusional limitation investigation,” Talanta, vol. 131, pp. 38–45, 2015.
View at: Publisher Site | Google Scholar
G. F. Drevon, K. Danielmeier, W. Federspiel et al., “High-activity enzyme-polyurethane coatings,” Biotechnology and Bioengineering, vol. 79, no. 7, pp. 785–794, 2002.
View at: Publisher Site | Google Scholar
V. R. Regina, H. Søhoel, A. R. Lokanathan et al., “Entrapment of subtilisin in ceramic sol-gel coating for antifouling applications,” ACS Applied Materials & Interfaces, vol. 4, no. 11, pp. 5915–5921, 2012.
View at: Publisher Site | Google Scholar
U. Kharchenko and I. Beleneva, “Evaluation of coatings corrosion resistance with biocomponents as antifouling additives,” Corrosion Science, vol. 72, pp. 47–53, 2013.
View at: Publisher Site | Google Scholar
C. S. McDaniel, J. McDaniel, M. E. Wales, and J. R. Wild, “Enzyme-based additives for paints and coatings,” Progress in Organic Coatings, vol. 55, no. 2, pp. 182–188, 2006.
View at: Publisher Site | Google Scholar
J. E. Gittens, T. J. Smith, R. Suleiman, and R. Akid, “Current and emerging environmentally-friendly systems for fouling control in the marine environment,” Biotechnology Advances, vol. 31, no. 8, pp. 1738–1753, 2013.
View at: Publisher Site | Google Scholar
P. Asuri, S. S. Karajanagi, R. S. Kane, and J. S. Dordick, “Polymer-nanotube-enzyme composites as active antifouling films,” Small, vol. 3, no. 1, pp. 50–53, 2007.
View at: Publisher Site | Google Scholar
C. Z. Dinu, I. V. Borkar, S. S. Bale, A. S. Campbell, R. S. Kane, and J. S. Dordick, “Perhydrolase-nanotube-paint sporicidal composites stabilized by intramolecular crosslinking,” Journal of Molecular Catalysis B: Enzymatic, vol. 75, pp. 20–26, 2012.
View at: Publisher Site | Google Scholar
R. C. Pangule, S. J. Brooks, C. Z. Dinu et al., “Antistaphylococcal nanocomposite films based on enzyme-nanotube conjugates,” ACS Nano, vol. 4, no. 7, pp. 3993–4000, 2010.
View at: Publisher Site | Google Scholar
G. Bayramoǧlu and M. Y. Arica, “Immobilization of laccase onto poly(glycidylmethacrylate) brush grafted poly(hydroxyethylmethacrylate) films: enzymatic oxidation of phenolic compounds,” Materials Science and Engineering C, vol. 29, no. 6, pp. 1990–1997, 2009.
View at: Publisher Site | Google Scholar
M. Faustini, L. Nicole, C. Boissière, P. Innocenzi, C. Sanchez, and D. Grosso, “Hydrophobic, antireflective, self-cleaning, and antifogging sol-gel coatings: an example of multifunctional nanostructured materials for photovoltaic cells,” Chemistry of Materials, vol. 22, no. 15, pp. 4406–4413, 2010.
View at: Publisher Site | Google Scholar
P. Asuri, S. S. Karajanagi, H. C. Yang, T.-J. Yim, R. S. Kane, and J. S. Dordick, “Increasing protein stability through control of the nanoscale environment,” Langmuir, vol. 22, no. 13, pp. 5833–5836, 2006.
View at: Publisher Site | Google Scholar
J. N. Talbert and J. M. Goddard, “Enzymes on material surfaces,” Colloids and Surfaces B: Biointerfaces, vol. 93, pp. 8–19, 2012.
View at: Publisher Site | Google Scholar
S. Yin, Y. Fujishiro, J. Wu, M. Aki, and T. Sato, “Synthesis and photocatalytic properties of fibrous titania by solvothermal reactions,” Journal of Materials Processing Technology, vol. 137, no. 1–3, pp. 45–48, 2003.
View at: Publisher Site | Google Scholar
C.-S. Kim, B. K. Moon, J.-H. Park, B.-C. Choi, and H.-J. Seo, “Solvothermal synthesis of nanocrystalline TiO₂ in toluene with surfactant,” Journal of Crystal Growth, vol. 257, no. 3-4, pp. 309–315, 2003.
View at: Publisher Site | Google Scholar
S. T. Aruna, S. Tirosh, and A. Zaban, “Nanosize rutile titania particle synthesis via a hydrothermal method without mineralizers,” Journal of Materials Chemistry, vol. 10, no. 10, pp. 2388–2391, 2000.
View at: Publisher Site | Google Scholar
Y. V. Kolen'ko, V. D. Maximov, A. V. Garshev, P. E. Meskin, N. N. Oleynikov, and B. R. Churagulov, “Hydrothermal synthesis of nanocrystalline and mesoporous titania from aqueous complex titanyl oxalate acid solutions,” Chemical Physics Letters, vol. 388, no. 4–6, pp. 411–415, 2004.
View at: Publisher Site | Google Scholar
Y. Mao, T.-J. Park, F. Zhang, H. Zhou, and S. S. Wong, “Environmentally friendly methodologies of nanostructure synthesis,” Small, vol. 3, no. 7, pp. 1122–1139, 2007.
View at: Publisher Site | Google Scholar
T. K. Ghorai, D. Dhak, S. K. Biswas, S. Dalai, and P. Pramanik, “Photocatalytic oxidation of organic dyes by nano-sized metal molybdate incorporated titanium dioxide (M_xMo_xTi_1−xO₆) (M=Ni, Cu, Zn) photocatalysts,” Journal of Molecular Catalysis A: Chemical, vol. 273, no. 1-2, pp. 224–229, 2007.
View at: Publisher Site | Google Scholar
D.-E. Gu, B.-C. Yang, and Y.-D. Hu, “V and N co-doped nanocrystal anatase TiO₂ photocatalysts with enhanced photocatalytic activity under visible light irradiation,” Catalysis Communications, vol. 9, no. 6, pp. 1472–1476, 2008.
View at: Publisher Site | Google Scholar
B.-H. Kim, J.-Y. Lee, Y.-H. Choa, M. Higuchi, and N. Mizutani, “Preparation of TiO₂ thin film by liquid sprayed mist CVD method,” Materials Science and Engineering B: Solid-State Materials for Advanced Technology, vol. 107, no. 3, pp. 289–294, 2004.
View at: Publisher Site | Google Scholar
L. L. Hench and J. K. West, “The sol-gel process,” Chemical Reviews, vol. 90, no. 1, pp. 33–72, 1990.
View at: Publisher Site | Google Scholar
J. Yu, X. Zhao, and Q. Zhao, “Effect of surface structure on photocatalytic activity of TiO₂ thin films prepared by sol-gel method,” Thin Solid Films, vol. 379, no. 1-2, pp. 7–14, 2000.
View at: Publisher Site | Google Scholar
N. P. Mellott, C. Durucan, C. G. Pantano, and M. Guglielmi, “Commercial and laboratory prepared titanium dioxide thin films for self-cleaning glasses: Photocatalytic performance and chemical durability,” Thin Solid Films, vol. 502, no. 1-2, pp. 112–120, 2006.
View at: Publisher Site | Google Scholar
R. L. Putnam, N. Nakagawa, K. M. McGrath et al., “Titanium dioxide—surfactant mesophases and Ti-TMS1,” Chemistry of Materials, vol. 9, no. 12, pp. 2690–2693, 1997.
View at: Publisher Site | Google Scholar
Y. Haga, H. An, and R. Yosomiya, “Photoconductive properties of TiO₂ films prepared by the sol-gel method and its application,” Journal of Materials Science, vol. 32, no. 12, pp. 3183–3188, 1997.
View at: Publisher Site | Google Scholar
U. Bach, D. Lupo, P. Comte et al., “Solid-state dye-sensitized mesoporous TiO₂ solar cells with high photon-to-electron conversion efficiencies,” Nature, vol. 395, no. 6702, pp. 583–585, 1998.
View at: Publisher Site | Google Scholar
N. I. Al-Salim, S. A. Bagshaw, A. Bittar et al., “Characterisation and activity of sol-gel-prepared TiO₂ photocatalysts modified with Ca, Sr or Ba ion additives,” Journal of Materials Chemistry, vol. 10, no. 10, pp. 2358–2363, 2000.
View at: Publisher Site | Google Scholar
J. Yu, J. C. Yu, B. Cheng, and X. Zhao, “Photocatalytic activity and characterization of the sol-gel derived Pb-doped TiO₂ thin films,” Journal of Sol-Gel Science and Technology, vol. 24, no. 1, pp. 39–48, 2002.
View at: Publisher Site | Google Scholar
H. E. Chao, Y. U. Yun, H. U. Xingfang, and A. Larbot, “Effect of silver doping on the phase transformation and grain growth of sol-gel titania powder,” Journal of the European Ceramic Society, vol. 23, no. 9, pp. 1457–1464, 2003.
View at: Publisher Site | Google Scholar
A. R. Phani and S. Santucci, “Structural characterization of iron titanium oxide synthesized by sol-gel spin-coating technique,” Materials Letters, vol. 50, no. 4, pp. 240–245, 2001.
View at: Publisher Site | Google Scholar
J. Wang, S. Uma, and K. J. Klabunde, “Visible light photocatalysis in transition metal incorporated titania-silica aerogels,” Applied Catalysis B: Environmental, vol. 48, no. 2, pp. 151–154, 2004.
View at: Publisher Site | Google Scholar
A. Di Paola, G. Marcì, L. Palmisano et al., “Preparation of polycrystalline TiO₂ photocatalysts impregnated with various transition metal ions: characterization and photocatalytic activity for the degradation of 4-nitrophenol,” The Journal of Physical Chemistry B, vol. 106, no. 3, pp. 637–645, 2002.
View at: Publisher Site | Google Scholar
F. B. Li and X. Z. Li, “Photocatalytic properties of gold/gold ion-modified titanium dioxide for wastewater treatment,” Applied Catalysis A: General, vol. 228, no. 1-2, pp. 15–27, 2002.
View at: Publisher Site | Google Scholar
F. B. Li, X. Z. Li, and M. F. Hou, “Photocatalytic degradation of 2-mercaptobenzothiazole in aqueous La³⁺-TiO₂ suspension for odor control,” Applied Catalysis B: Environmental, vol. 48, no. 3, pp. 185–194, 2004.
View at: Publisher Site | Google Scholar
D. Byun, Y. Jin, B. Kim, J. Kee Lee, and D. Park, “Photocatalytic TiO₂ deposition by chemical vapor deposition,” Journal of Hazardous Materials, vol. 73, no. 2, pp. 199–206, 2000.
View at: Publisher Site | Google Scholar
K. L. Choy, “Chemical vapour deposition of coatings,” Progress in Materials Science, vol. 48, no. 2, pp. 57–170, 2003.
View at: Publisher Site | Google Scholar
R. van de Krol, A. Goossens, and J. Schoonman, “Mott-schottky analysis of nanometer-scale thin-film anatase TiO₂,” Journal of the Electrochemical Society, vol. 144, no. 5, pp. 1723–1727, 1997.
View at: Publisher Site | Google Scholar
A. Smith and R. Rodriguez-Clemente, “Morphological differences in ZnO films deposited by the pyrosol technique: effect of HCl,” Thin Solid Films, vol. 345, no. 2, pp. 192–196, 1999.
View at: Publisher Site | Google Scholar
D. F. Paraguay, L. W. Estrada, N. D. R. Acosta, E. Andrade, and M. Miki-Yoshida, “Growth, structure and optical characterization of high quality ZnO thin films obtained by spray pyrolysis,” Thin Solid Films, vol. 350, no. 1-2, pp. 192–202, 1999.
View at: Publisher Site | Google Scholar
R. Zhang and L. Gao, “Preparation of nanosized titania by hydrolysis of alkoxide titanium in micelles,” Materials Research Bulletin, vol. 37, no. 9, pp. 1659–1666, 2002.
View at: Publisher Site | Google Scholar
I. Zhitomirsky, “Cathodic electrosynthesis of titanium and ruthenium oxides,” Materials Letters, vol. 33, no. 5-6, pp. 305–310, 1998.
View at: Publisher Site | Google Scholar
K. Kamada, M. Mukai, and Y. Matsumoto, “Electrodeposition of titanium(IV) oxide film from sacrificial titanium anode in I2-added acetone bath,” Electrochimica Acta, vol. 47, no. 20, pp. 3309–3313, 2002.
View at: Publisher Site | Google Scholar
S. Takeda, S. Suzuki, H. Odaka, and H. Hosono, “Photocatalytic TiO₂ thin film deposited onto glass by DC magnetron sputtering,” Thin Solid Films, vol. 392, no. 2, pp. 338–344, 2001.
View at: Publisher Site | Google Scholar
V. Pore, A. Rahtu, M. Leskelä, M. Ritala, T. Sajavaara, and J. Keinonen, “Atomic layer deposition of photocatalytic TiO₂ thin films from titanium tetramethoxide and water,” Chemical Vapor Deposition, vol. 10, no. 3, pp. 143–148, 2004.
View at: Publisher Site | Google Scholar
J. Bouclé, P. Ravirajan, and J. Nelson, “Hybrid polymer-metal oxide thin films for photovoltaic applications,” Journal of Materials Chemistry, vol. 17, no. 30, pp. 3141–3153, 2007.
View at: Publisher Site | Google Scholar
M. Miyauchi, A. Nakajima, T. Watanabe, and K. Hashimoto, “Photocatalysis and photoinduced hydrophilicity of various metal oxide thin films,” Chemistry of Materials, vol. 14, no. 6, pp. 2812–2816, 2002.
View at: Publisher Site | Google Scholar
Y. Gushikem and S. S. Rosatto, “Metal oxide thin films grafted on silica gel surfaces: recent advances on the analytical application of these materials,” Journal of the Brazilian Chemical Society, vol. 12, no. 6, pp. 695–705, 2001.
View at: Google Scholar
D. Gong, C. A. Grimes, O. K. Varghese et al., “Titanium oxide nanotube arrays prepared by anodic oxidation,” Journal of Materials Research, vol. 16, no. 12, pp. 3331–3334, 2001.
View at: Publisher Site | Google Scholar
S. G. Kandalkar, J. L. Gunjakar, and C. D. Lokhande, “Preparation of cobalt oxide thin films and its use in supercapacitor application,” Applied Surface Science, vol. 254, no. 17, pp. 5540–5544, 2008.
View at: Publisher Site | Google Scholar
J. H. Seinfeld and S. N. Pandis, Atmospheric Chemistry and Physics: From Air Pollution to Climate Change, John Wiley & Sons, 2012.
M. Azhar Khan, M. Zahir Khan, K. Zaman, and L. Naz, “Global estimates of energy consumption and greenhouse gas emissions,” Renewable and Sustainable Energy Reviews, vol. 29, pp. 336–344, 2014.
View at: Publisher Site | Google Scholar
D. Buchan, “Energy and climate change: Europe at the crossroads,” Journal of Contemporary European Research, vol. 6, no. 3, p. 419, 2010.
View at: Google Scholar
M. F. Montemor, “Functional and smart coatings for corrosion protection: a review of recent advances,” Surface and Coatings Technology, vol. 258, pp. 17–37, 2014.
View at: Publisher Site | Google Scholar
D. G. Rickerby and M. Morrison, “Nanotechnology and the environment: a European perspective,” Science and Technology of Advanced Materials, vol. 8, no. 1-2, pp. 19–24, 2007.
View at: Publisher Site | Google Scholar
J. M. Gadekar and K. D. Kadam, “Nanotechnology: green innovation,” International Journal of Science and Research, vol. 3, no. 1, 2014.
View at: Google Scholar
R. A. McIntyre, “Common nano-materials and their use in real world applications,” Science Progress, vol. 95, no. 1, pp. 1–22, 2012.
View at: Publisher Site | Google Scholar
T. P. Chou, C. Chandrasekaran, S. J. Limmer et al., “Organic–inorganic hybrid coatings for corrosion protection,” Journal of Non-Crystalline Solids, vol. 290, no. 2-3, pp. 153–162, 2001.
View at: Publisher Site | Google Scholar

Copyright

Copyright © 2015 Suzan Biran Ay and Nihan Kosku Perkgoz. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

PDF Download Citation

Download other formats

Order printed copies

Views

3302

Downloads

1284

Citations