Photocatalytic Activity of Ag-TiO<sub>2</sub> Composites Deposited by Photoreduction under UV Irradiation

Díaz-Uribe, Carlos; Viloria, Jose; Cervantes, Lorraine; Vallejo, William; Navarro, Karen; Romero, Eduard; Quiñones, Cesar

doi:https://doi.org/10.1155/2018/6080432

International Journal of Photoenergy

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Abstract Introduction Experimental Results Conclusions Data Availability Conflicts of Interest Acknowledgments References Copyright Related Articles

Research Article | Open Access

Volume 2018 | Article ID 6080432 | https://doi.org/10.1155/2018/6080432

Photocatalytic Activity of Ag-TiO₂ Composites Deposited by Photoreduction under UV Irradiation

Carlos Díaz-Uribe,¹Jose Viloria,¹Lorraine Cervantes,¹William Vallejo,¹Karen Navarro,^1,2Eduard Romero,³and Cesar Quiñones⁴

Academic Editor: Mohammad Muneer

Received30 Apr 2018

Revised29 Jul 2018

Accepted23 Aug 2018

Published21 Oct 2018

Abstract

In this work, we synthesized Ag nanoparticles on TiO₂ thin films deposited on soda lime glass substrates. Ag nanoparticles were synthesized by photoreduction under UV irradiation silver nitrate solution. X-ray diffraction, Raman spectroscopy, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) measurements were used for physicochemical characterization. The structural study showed that all samples were polycrystalline, main phases were anatase and rutile, and no additional signals were detected after surface modification. Raman spectroscopy suggested that silver aggregates deposited on the TiO₂ films could exhibit the surface plasmon resonance (SPR) phenomenon; XPS and SEM analysis confirmed TiO₂ film morphological modification after photoreduction process. Photocatalytic degradation of methylene blue (MB) was studied under UV irradiation in aqueous solution, and, besides, pseudo-first-order model was used to obtain kinetic information about photocatalytic degradation. Results indicated that Ag-TiO₂ showed an important increase in photocatalytic activity under UV (from 20% to 35%); finally, Ag-TiO₂ thin films had value 2.4 × 10⁻³ ± 0.003 min⁻¹ of 1.8 times greater than the value 1.3 × 10⁻⁴ ± 0.0004 min⁻¹ of TiO₂ thin films.

1. Introduction

Nowadays, titanium dioxide (TiO₂) is one of the most important semiconductors in photocatalytic applications because of its prominent properties (e.g., it is harmful, stable, resistant to photocorrosion, inexpensive, and has high photocatalytic properties in the degradation of different pollutants) [1, 2]. However, despite all their characteristics, TiO₂ has three main drawbacks: (a) fast recombination rate of photogenerated electron-hole pair, (b) low quantum yield in the photocatalytic reactions in aqueous solutions, and (c) a high bandgap value (3.2 eV, photocatalytic active only under UV irradiation) [3–5]. Due to energy transfer that must be efficient during electron-hole pair separation, fast recombination of the photogenerated charge pair (e⁻/h⁺) after activation of semiconductor is an important drawback for using titanium dioxide (TiO₂) as a photocatalyst, because it inhibits redox processes and reduces strongly photocatalytic efficiency [6–8]. Two strategies have been explored to solve this drawback: (a) TiO₂ synthesis methods can be modified and optimized and (b) the TiO₂ surface can be modified. TiO₂ surface modification by transition metal deposition (e.g., silver, platinum, ruthenium, and palladium) has been reported to decrease the recombination process by forming heterostructures and new interfaces that improve semiconductor photocatalytic properties [9–11]. Noble metal cocatalysts can improve photocatalytic properties of semiconductor because they act as electron traps near to conduction bands and/or they improve surface electron excitation by surface plasmonic resonance [12–14]. Nalbandian et al. fabricated Ag-TiO₂ nanofibers by electrospinning, and they showed that the presence of the Ag cocatalyst enhanced reactivity [15]. Yilmaz et al. deposited photochemically Pd nanoparticles on TiO₂ nanorods, and they corroborated that electron transfer between Pd and TiO₂ was improved after modification process [16]. Currently, different reports showed advances for the fabrication of Ag/TiO₂ nanoheterostructure catalysts (e.g., Ag-modified TiO₂ nanoparticles, nanowires, and nanorods) [17, 18]; however, several practical problems arise from the use of powder during the photocatalytic process: (a) separation of insoluble catalyst from suspension is harder, (b) particles in suspensions create aggregates especially at high concentrations, and (c) suspensions are difficult to apply on continuous flow systems. The TiO₂ thin film is an efficient alternative to solve these drawbacks.

In this contribution, we evaluate the photocatalytic activity of Ag-TiO₂ composite thin films in the degradation of methylene blue as a potential alternative in photocatalysis.

2. Experimental

2.1. Photocatalyst Synthesis

TiO₂ films were deposited on soda lime glass (SLG) by doctor blade method. TiO2-Degussa powder (P25) was used as reagent, and after this process, 1.5 μm TiO₂ thin film thickness was obtained [19]. Silver particle deposition on TiO₂ films was carried out by chemical photoreduction: first, TiO₂ films were immersed in an aqueous silver nitrate solution (8.0 × 10⁻² M) for 30 and 60 minutes; after the photoreduction process, TiO₂ film colors changed from white to grayish brown.

2.2. Photocatalyst Characterization

We study thin film physicochemical properties through measurements of Raman spectroscopy, X-ray diffraction (XRD), and scanning electronic microscopy (SEM); furthermore, the thickness of the thin films was measured through a Veeco Dektak 150 profilometer. Raman spectra were recorded on DRX Raman microscope with laser at 680 nm; SEM images were carried out using a Cambridge S360 microscope operating at acceleration voltage of 20 kV with a scanned area 11 μm × 10 μm, and XRD X-ray diffraction patterns of the samples were recorded in Shimadzu 6000 diffractometer with a source of CuKα radiation ( nm) in a range diffraction angle between 20° and 70°. Finally, XPS measurements were performed on X-ray photoelectronic spectrometer (NAP-XPS; brand Specs) with a PHOIBOS 150 1D-DLD analyzer, using a monochromatic source of Al-K_α (1486.7 eV, 13 kV, 100 W) with energy from the 90 eV for the general spectra and 20 eV for the high-resolution spectra. The step was 1 eV for the general spectra and 0.1 eV for the high spectra. We performed 20 measurement cycles for the high-resolution spectra and 3 for the general spectra.

2.3. Photocatalytic Activity

Thin films were immersed in blue methylene solution (10 ppm was used as target solution), and prior to irradiation, the system was magnetically stirred in the dark by 1 hour to ensure the equilibrium of dye adsorption-desorption on thin film surface. The system was irradiated by UV lamp with an emission maximum of 260 nm and power 30 W during 180 minutes. All the tests of catalytic reactivity were carried out in aerobic conditions (magnetically stirred: 150 rpm); the irradiated surface area was 3.0 cm², and the volume of the suspension was 0.015 l. The incident photon flow per unit volume (= 1.3 × 10⁻⁶ EinsteinL⁻¹s⁻¹; Figure 1) shows a general scheme of photoreactor. We chose methylene blue as the model compound because of, since 2010, International Organization for Standardization (ISO) published standard: 10678:2010, namely, the “Determination of photocatalytic activity of surfaces in an aqueous medium by degradation of methylene blue” [20]. Finally, the concentration of dye was determined by spectrophotometry at nm for using calibration curve (correlation coefficient ).

3. Results

3.1. SEM Analysis

SEM and EDS were used for morphological compound characterization. Figure 2 shows SEM images for both TiO₂ and Ag-TiO₂ thin films. Figures 2(a) and 2(b) show that the microaggregates compose TiO₂ films: microaggregates have a size range around 50 nm; these results are according to the typical morphology of TiO₂-Degussa P25 [21]. Figures 2(c) and 2(d) show the morphological results to Ag-TiO₂ thin films; the SEM image allows to differentiate the deposited silver particles. Figure 2 shows the photoreduced particles agglomerated reaching sizes of the order of 200 nm. The EDS analysis showed that the agglomerates observed in the surface of TiO₂ corresponded to silver particles (Figures 2(e)).

(a)

(b)

(c)

(d)

(e)

3.2. Raman Assay

Figure 3 shows the Raman spectrum for TiO₂ films and the Ag-TiO₂ composite thin films deposited after 30 minutes of UV light irradiation. TiO₂ films showed characteristic vibration Raman mode signals to anatase phase: signals located at 144 cm⁻¹, 398 cm⁻¹, and 520 cm⁻¹ are assigned to E_1g vibration mode, for the signal located at 639 cm⁻¹, it is attributed to 398 cm⁻¹ E_3g vibration mode, and results are according to other reports [22]. Raman spectrum of the modified Ag-TiO₂ thin films shows same signals than TiO₂ thin films; however, the intensity of all signals is increasing; this behavior is associated to phenomenon known as surface plasmon resonance (SPR). This process is characterized by the increase in several orders of magnitude of the intensity of the signals in the Raman spectrum due to the effect of metal nanometric scale species adsorbed on semiconductor surface [23–25]. Different reports indicated that some noble metal nanoparticles (gold, silver, palladium, and platinum) can generate an intense surface plasmon resonance when adsorbed onto semiconductors; finally, SPR process could affect optical, electrical, and photocatalytic properties of TiO₂ [26, 27].

3.3. XRD Assay

Figure 4 shows the experimental XRD pattern for both TiO₂ and Ag-TiO₂ thin films. XRD pattern showed peaks at , , , and ; they correspond to planes (101), (112), (200), and (204). These signals are typical of the TiO₂ anatase phase (JCPDS #071-1166); diffraction pattern also shows additional diffraction signals at and ; these reflections can be associated to the planes (110) and (220) of the rutile crystalline phase (JCPDS #021-1276). The presence of the rutile is due to the composition of the material used as TiO₂ source (Degussa P25). Furthermore, after Ag photoreduction on TiO₂ surface, the intensity of main signal (located at ) decreases indicating that the anchoring process did not change the characteristic crystal surface structure of TiO₂; these results are according to SEM assay [28].

3.4. XPS Assay

XPS measurements were conducted to verify the surface components and valence states of Ag-TiO₂ thin film. Figure 5(a) shows profile XPS spectrum to Ag-TiO₂ thin film. The profile of the sample shows the typical signals of binding energy corresponding to Ag, Ti, O, and C elements.

(a)

(b)

(c)

The signals at 574.0 eV, 374.0 eV, and 368.0 eV correspond to the electronic transitions of Ag 3p_3/2, Ag 3d_3/2, and Ag 3d_3/2, respectively; Figure 5(c) plots the HRXPS spectrum of Ag 3d_5/2 and Ag 3d_3/2 double peaks, which are centered at 367.8 and 373.8 eV, respectively; and the splitting of the 3d doublet was 6.0 eV. This binding energy indicated that silver was of metallic nature. These results are according to other reports [29–31]. Figure 5(b) shows the peaks at 458.6 and 464.3 eV; these signals correspond to Ti 2p_3/2 and Ti 2p_1/2 indicating the formation of Ti⁴⁺ in TiO₂ [32–34]. Figure 5(a) also shows an important signal at 530.2 eV, and this corresponds to the phototransition O1s; finally, the signal located at 285 eV corresponds to electronic transition of C 1s. This signal is typical of atmospheric CO₂ absorbed on the surface of the simple.

We performed quantitative assay of Ag-TiO₂ thin films for using XPS survey spectra shown in Figure 5; it mainly consists in determination of the relative concentration of respective surface atoms like Ti, O, C, and Ag as follows: where corresponds to relative intensity height of the O_1s, Ti_2p, Ag_3d, and C_1s core-level line peaks and is the atomic sensitivity factors related to the height of specific peaks [35–37]. Table 1 summarizes the corresponding partial concentration of specific elements in the Ag-TiO₂ thin films.

3.5. Photocatalytic Assay

Figure 6 shows the (methylene blue) as a function of time under UV irradiation, in the presence of TiO₂ and Ag-TiO₂ thin films for 180 min. Figure 6 shows similar profile to behavior observed for the photocatalytic degradation of different dyes; previous studies showed that photocatalytic degradation rate of textile dyes in heterogeneous photocatalytic oxidation systems under UV light illumination followed Langmuir–Hinshelwood (L–H); the Langmuir–Hinshelwood expression that explains the kinetics of heterogeneous catalytic systems is given by [38–44] where is the rate of dye mineralization, is the rate constant, is the methylene blue concentration, and is the adsorption coefficient. Equation (1) can be solved explicitly for by using discrete changes in [MB] from the initial concentration to a zero reference point; however, when the concentration of substrate is in the scale of μmoles, an apparent first-order model can be assumed; in our case,

Integration of (2): where represents time in minutes, () is the apparent reaction rate constant (min⁻¹), and is the concentration of MB at each time. (L–H) kinetics is commonly used to explain the kinetics of the heterogeneous catalytic processes; the assumption of a pseudo-first-order kinetic model was used in several studies to characterize the effect of different experimental conditions [45–47]. Figure 6 shows that when the MB solution was exposed to UV radiation on TiO₂ thin films, a small reduction in the concentration of MB was observed (near 20%). These results are according to expected because TiO₂ thin films are photocatalytic active under this kind of radiation. Visible is a typical behavior for TiO₂ due to their well-known wide bandgap value [48].

Furthermore, Figure 6 shows that Ag-TiO₂ thin films showed an important increase in the photocatalytic activity under UV (near 35%); these results could be due to the silver aggregates deposited on the TiO₂ surface that can accumulate charge and accept electrons inside the semiconductor. The accumulation of electrons can reduce the carrier’s recombination increasing generation of reactive oxygen species, and besides, Ag particle on TiO₂ can change and a collective oscillation can be generated, which is known as localized surface plasmon resonance (SPR) [49]; according to other reports, silver particles exhibit collective oscillation of their electrons in the conduction band, and it is suggested that the association between the semiconductor and the metal can increase photocatalytic activity, which coincides with the results obtained in this work [50]. Pseudo-first-order model was applied to kinetic data of Figure 6. The values for each test were determined from the slope of the linear fitting of vs time (Figure 7).

Ag-TiO₂ thin films had a value 2.4 × 10⁻³ min⁻¹; this value was 1.8 times greater than the value 1.3 × 10⁻⁴ min⁻¹ of TiO₂ thin films. values confirmed that the photoreduction process was effective and demonstrated that this method could be used as an alternative to increasing the photocatalytic activity of TiO₂ under UV light irradiation. We reported in a previous work that Ag-TiO₂ thin films had antimicrobial activity against Staphylococcus aureus; same material demonstrated both photocatalytic and antimicrobial activities [51]. Reactive oxygen species generated in advance oxidation process are endogenous, highly reactive, oxygen molecules, and these species can originate oxidation reactions of many organic and biological compounds (e.g., singlet oxygen and oxygen free radicals such as hydroxyl radical, superoxide anion, hydroperoxyl (HOO^⋅), or other similar radicals); our results corroborate high reactivity of these chemical species [52].

4. Conclusions

In this work, we deposited Ag microaggregates on TiO₂ thin films. SEM characterization demonstrated microaggregate formation on TiO₂ surface, and besides, Raman spectroscopy indicated that surface modification generated SPR process; furthermore, XRD assay indicated that all thin films were crystalline and XPS assay indicates that silver was of metallic nature after photoreduction on TiO₂ thin films. Photocatalytic activity of Ag-TiO₂ thin films was higher than that of TiO₂ thin films; kinetic results showed that the for Ag-TiO₂ thin films was greater (2.4 × 10⁻³ min⁻¹) than the for TiO₂ thin films (1.3 × 10⁻³ min⁻¹).

Data Availability

The data used to support the findings of this study are available from the corresponding author upon request.

Conflicts of Interest

The authors declare that they have no conflicts of interest.

Acknowledgments

This research was supported by Universidad del Atlántico. Furthermore, the authors thank Universidad de Antioquia for supporting the XPS measurements.

References

J. Schneider, M. Matsuoka, M. Takeuchi et al., “Understanding TiO₂ photocatalysis: mechanisms and materials,” Chemical Reviews, vol. 114, no. 19, pp. 9919–9986, 2014.
View at: Publisher Site | Google Scholar
M. J. G azquez, J. P. Bolívar, R. Garcia-Tenorio, and F. Vaca, “A review of the production cycle of titanium dioxide pigment,” Materials Sciences and Applications, vol. 5, no. 7, pp. 441–458, 2014.
View at: Publisher Site | Google Scholar
Y. Du and J. Rabani, “The measure of TiO₂ photocatalytic efficiency and the comparison of different photocatalytic titania,” The Journal of Physical Chemistry. B, vol. 107, no. 43, pp. 11970–11978, 2003.
View at: Publisher Site | Google Scholar
C. Ming, Y. Ku, F. Tien, and Y. L. Kuo, “Effect of platinum on the decomposition efficiency and apparent quantum yield of photocatalysis of isopropanol in an annular photoreactor,” Journal of Advanced Oxidation Technologies, vol. 10, no. 2, pp. 36–368, 2007.
View at: Publisher Site | Google Scholar
B. Kılıç, N. Gedik, S. Pıravadıllı, A. Serhan, and E. Gürd, “Band gap engineering and modifying surface of TiO₂ nanostructures by Fe₂O₃ for enhanced-performance of dye sensitized solar cell,” Materials Science in Semiconductor Processing, vol. 31, pp. 363–371, 2015.
View at: Publisher Site | Google Scholar
P. Zawadzki, A. B. Laursen, K. W. Jacobsen, S. Dahl, and J. Rossmeisl, “Oxidative trends of TiO₂ – hole trapping at anatase and rutile surfaces,” Energy & Environmental Science, vol. 5, no. 12, pp. 9866–9869, 2012.
View at: Publisher Site | Google Scholar
L. Cavigli, F. Bogani, A. Vinattieri et al., “Carrier recombination dynamics in anatase TiO₂ nanoparticles,” Solid State Sciences, vol. 12, no. 11, pp. 1877–1880, 2010.
View at: Publisher Site | Google Scholar
D. Punnoose, C. H. S. S. Pavan, H. Woong et al., “Reduced recombination with an optimized barrier layer on TiO₂ in PbS/CdS core shell quantum dot sensitized solar cells,” New Journal of Chemistry, vol. 40, no. 4, pp. 3423–3431, 2016.
View at: Publisher Site | Google Scholar
N. Rahimi, R. A. Pax, and E. M. Gray, Progress in Solid State Chemistry, vol. 44, no. 3, pp. 86–105, 2016.
View at: Publisher Site
A. Bumajdad and M. Madkour, “Understanding the superior photocatalytic activity of noble metals modified titania under UV and visible light irradiation,” Physical Chemistry Chemical Physics, vol. 16, no. 16, pp. 7146–7158, 2014.
View at: Publisher Site | Google Scholar
J. Choi, H. Park, and M. R. Hoffmann, “Effects of single metal-ion doping on the visible-light photoreactivity of TiO₂,” The Journal of Physical Chemistry C, vol. 114, no. 2, pp. 783–792, 2009.
View at: Publisher Site | Google Scholar
M. Kotesh, K. Bhavani, G. Naresh, B. Srinivas, and A. Venugopala, “Plasmonic resonance nature of Ag-Cu/TiO₂ photocatalyst under solar and artificial light: synthesis, characterization and evaluation of H₂O splitting activity,” Applied Catalysis B: Environmental, vol. 199, pp. 282–291, 2016.
View at: Publisher Site | Google Scholar
S. Shuang, R. Lv, Z. Xie, and Z. Zhang, “Surface plasmon enhanced photocatalysis of Au/Pt-decorated TiO₂ nanopillar arrays,” Scientific Reports, vol. 6, pp. 1–8, 2016.
View at: Google Scholar
S. Kochuveedu, D. Kim, and D. Ha Kim, “Surface-plasmon-induced visible light photocatalytic activity of TiO₂ nanospheres decorated by Au nanoparticles with controlled configuration,” The Journal of Physical Chemistry C, vol. 116, no. 3, pp. 2500–2506, 2012.
View at: Publisher Site | Google Scholar
M. J. Nalbandian, M. Zhang, J. Sanchez et al., “Synthesis and optimization of Ag–TiO₂ composite nanofibers for photocatalytic treatment of impaired water sources,” Journal of Hazardous Materials, vol. 299, pp. 141–148, 2015.
View at: Publisher Site | Google Scholar
P. Yilmaz, A. Lacerda, I. Larrosa, and S. Dunn, “Photoelectrocatalysis of rhodamine B and solar hydrogen production by TiO₂ and Pd/TiO₂ catalyst systems,” Electrochimica Acta, vol. 231, pp. 641–649, 2017.
View at: Publisher Site | Google Scholar
C. Su, L. Liu, M. Zhang, Y. Zhanga, and C. Shao, “Fabrication of Ag/TiO₂ nanoheterostructures with visible light photocatalytic function via a solvothermal approach,” CrystEngComm, vol. 14, no. 11, pp. 3989–3999, 2012.
View at: Publisher Site | Google Scholar
K. Kusdianto, D. Jiang, M. Kubo, and M. Shimada, “Fabrication of TiO₂–Ag nanocomposite thin films via one-step gas-phase deposition,” Ceramics International, vol. 43, no. 6, pp. 5351–5355, 2017.
View at: Publisher Site | Google Scholar
C. Quiñones, Y. Ayala, and W. Vallejo, “Methylene blue photoelectrodegradation under UV irradiation on Au/Pd-modified TiO₂ films,” Applied Surface Science, vol. 257, no. 2, pp. 367–371, 2010.
View at: Publisher Site | Google Scholar
A. Mills, “An overview of the methylene blue ISO test for assessing the activities of photocatalytic films,” Applied Catalysis B: Environmental, vol. 128, pp. 144–149, 2012.
View at: Publisher Site | Google Scholar
I. Ahmed, Z. Khan, and M. Ali, “Photocatalytic degradation of nitro and chlorophenols using doped and undoped titanium dioxide nanoparticles,” Journal of Nanomaterials, vol. 2011, Article ID 589185, 8 pages, 2011.
View at: Publisher Site | Google Scholar
N. Mahdjoub, N. Allen, P. Kelly, and V. Vishnyakov, “SEM and Raman study of thermally treated TiO₂ anatase nanopowders: influence of calcination on photocatalytic activity,” Journal of Photochemistry and Photobiology A: Chemistry, vol. 211, no. 1, pp. 59–64, 2010.
View at: Publisher Site | Google Scholar
M. Torrell, R. Kabir, L. Cunha et al., “Tuning of the surface plasmon resonance in TiO₂/Au thin films grown by magnetron sputtering: the effect of thermal annealing,” Journal of Applied Physics, vol. 109, no. 7, article 074310, 2011.
View at: Publisher Site | Google Scholar
A. Tanaka, S. Sakaguchi, K. Hashimoto, and H. Kominami, “Preparation of Au/TiO₂ with metal cocatalysts exhibiting strong surface plasmon resonance effective for photoinduced hydrogen formation under irradiation of visible light,” ACS Catalysis, vol. 3, no. 1, pp. 79–85, 2013.
View at: Publisher Site | Google Scholar
A. Tanaka, K. Teramura, S. Hosokawa, H. Kominamic, and T. Tanaka, “Visible light-induced water splitting in an aqueous suspension of a plasmonic Au/TiO₂ photocatalyst with metal co-catalysts,” Chemical Science, vol. 8, no. 4, pp. 2574–2580, 2017.
View at: Publisher Site | Google Scholar
K. H. Leong, H. Y. Chu, S. Ibrahim, and P. Saravanan, “Palladium nanoparticles anchored to anatase TiO₂ for enhanced surface plasmon resonance-stimulated, visible-light-driven photocatalytic activity,” Beilstein Journal of Nanotechnology, vol. 6, pp. 428–437, 2015.
View at: Publisher Site | Google Scholar
M. Zhou, J. Zhang, B. Cheng, and H. Yu, “Enhancement of visible-light photocatalytic activity of mesoporous Au-TiO₂ nanocomposites by surface plasmon resonance,” vol. 2012, Article ID 532843, 10 pages, 2012.
View at: Publisher Site | Google Scholar
Z. Huang, B. Zheng, S. Zhu et al., “Photocatalytic activity of phthalocyanine-sensitized TiO₂–SiO₂ microparticles irradiated by visible light,” Materials Science in Semiconductor Processing, vol. 25, pp. 148–152, 2014.
View at: Publisher Site | Google Scholar
J. Yu, J. Xiong, B. Cheng, and S. Liu, “Fabrication and characterization of Ag–TiO₂ multiphase nanocomposite thin films with enhanced photocatalytic activity,” Applied Catalysis B: Environmental, vol. 60, no. 3-4, pp. 211–221, 2005.
View at: Publisher Site | Google Scholar
J. F. Moulder, W. F. Stickle, P. E. Sobol, and K. D. Bomben, Handbook of X-Ray Photoelectron Spectroscopy, Perkin-Elmer Corporation Physical Electronics Division, 1992.
E. Stathatos and P. Lianos, “Photocatalytically deposited silver nanoparticles on mesoporous TiO₂ films,” Langmuir, vol. 16, no. 5, pp. 2398–2400, 2000.
View at: Publisher Site | Google Scholar
L. Ma, Y. Huang, M. Hou, Z. Xie, and Z. Zhang, “Ag nanorods coated with ultrathin TiO₂ shells as stable and recyclable SERS substrates,” Scientific Reports, vol. 5, no. 1, article 15442, 2015.
View at: Publisher Site | Google Scholar
J. Chen, H. Su, X. You, J. Gao, W. M. Lau, and D. Zhang, “3D TiO₂ submicrostructures decorated by silver nanoparticles as SERS substrate for organic pollutants detection and degradation,” Materials Research Bulletin, vol. 49, pp. 560–565, 2014.
View at: Publisher Site | Google Scholar
B. Erdem, R. A. Hunsicker, G. W. Simmons, E. D. Sudol, V. L. Dimonie, and M. S. El-Aasser, “XPS and FTIR surface characterization of TiO₂ particles used in polymer encapsulation,” Langmuir, vol. 17, no. 9, pp. 2664–2669, 2001.
View at: Publisher Site | Google Scholar
M. Kwoka, V. Galstyan, E. Comini, and J. Szube, “Pure and highly Nb-doped titanium dioxide nanotubular arrays: characterization of local surface properties,” Nanomaterials, vol. 7, no. 12, p. 456, 2017.
View at: Publisher Site | Google Scholar
J. F. Watts and J. Wolstenholme, An introduction to surface analysis by XPS and AES, John Wiley & Sons, Ltd, 2003.
View at: Publisher Site
J. C. Vickerman and I. S. Gilmore, “Surface analysis—the principal techniques,” Tech. Rep., John Wiley & Sons, Chichester, UK, 2009.
View at: Google Scholar
S. Ghasemi, S. Rahimnejad, S. Rahman Setayesh, M. Hosseini, and M. R. Gholami, “Kinetics investigation of the photocatalytic degradation of acid blue 92 in aqueous solution using nanocrystalline TiO₂ prepared in an ionic liquid,” Progress in Reaction Kinetics and Mechanism, vol. 34, no. 1, pp. 55–76, 2009.
View at: Publisher Site | Google Scholar
I. Konstantinou and T. Albanis, “TiO₂-assisted photocatalytic degradation of azo dyes in aqueous solution: kinetic and mechanistic investigations: a review,” Applied Catalysis B: Environmental, vol. 49, no. 1, pp. 1–14, 2004.
View at: Publisher Site | Google Scholar
K. V. Kumar, K. Porkodi, and F. Rocha, “Langmuir–Hinshelwood kinetics – a theoretical study,” Catalysis Communications, vol. 9, no. 1, pp. 82–84, 2008.
View at: Publisher Site | Google Scholar
A. R. Khataee, M. Fathinia, and S. Aber, “Kinetic modeling of liquid phase photocatalysis on supported TiO₂ nanoparticles in a rectangular flat-plate photoreactor,” Industrial & Engineering Chemistry Research, vol. 49, no. 24, pp. 12358–12364, 2010.
View at: Publisher Site | Google Scholar
V. Djokic, J. Vujovic, A. Marinkovic et al., “A study of the photocatalytic degradation of the textile dye CI basic yellow 28 in water using a P160 TiO₂-based catalyst,” Journal of the Serbian Chemical Society, vol. 77, no. 12, pp. 1747–1757, 2012.
View at: Publisher Site | Google Scholar
L. Elsellami, F. Vocanson, and F. Dappozzeetal, “Kinetic of adsorption and of photocatalytic degradation of phenylalanine effect of pH and light intensity,” Applied Catalysis A: General, vol. 380, no. 1-2, pp. 142–148, 2010.
View at: Publisher Site | Google Scholar
N. P. Xekoukoulotakis, C. Drosou, C. Brebou et al., “Kinetics of UV-A/TiO₂ photocatalytic degradation and mineralization of the antibiotic sulfamethoxazole in aqueous matrices,” Catalysis Today, vol. 161, no. 1, pp. 163–168, 2011.
View at: Publisher Site | Google Scholar
C. S. Turchi and D. Ollis, “Photocatalytic degradation of organic water contaminants: mechanisms involving hydroxyl radical attack,” Journal of Catalysis, vol. 122, no. 1, pp. 178–192, 1990.
View at: Publisher Site | Google Scholar
T. Zhang, T. Oyama, A. Aoshima, H. Hidaka, J. Zhao, and N. Serpone, “Photooxidative N-demethylation of methylene blue in aqueous TiO₂ dispersions under UV irradiation,” Journal of Photochemistry and Photobiology A: Chemistry, vol. 140, no. 2, pp. 163–172, 2001.
View at: Publisher Site | Google Scholar
J. W. Rodriguez-Acosta, M. Á. Mueses, and F. Machuca-Martínez, “Mixing rules formulation for a kinetic model of the Langmuir-Hinshelwood semipredictive type applied to the heterogeneous photocatalytic degradation of multicomponent mixtures,” International Journal of Photoenergy, vol. 2014, Article ID 817538, 9 pages, 2014.
View at: Publisher Site | Google Scholar
C. Xu, G. P. Rangaiah, and X. S. Zhao, “Photocatalytic degradation of methylene blue by titanium dioxide: experimental and modeling study,” Industrial and Engineering Chemistry Research, vol. 53, no. 38, pp. 14641–14649, 2014.
View at: Publisher Site | Google Scholar
P. Liu, P. Zhang, D. Liang, and W. Xue, “Preparation, characterization and photodegradation of methylene blue based on TiO₂ microparticles modified with thiophene substituents,” Chinese Science Bulletin, vol. 57, no. 33, pp. 4381–4386, 2012.
View at: Publisher Site | Google Scholar
R. S. André, C. A. Zamperini, E. G. Mima et al., “Antimicrobial activity of TiO₂: Ag nanocrystalline heterostructures: experimental and theoretical insights,” Chemical Physics, vol. 459, pp. 87–95, 2015.
View at: Publisher Site | Google Scholar
W. Vallejo, C. Díaz-Uribe, K. Navarro, R. Valle, J. W. Arboleda, and E. Romero, “Estudio de la actividad antimicrobiana de películas delgadas de dióxido de titanio modificado con plata,” Revista de la Academia Colombiana de Ciencias Exactas, Físicas y Naturales, vol. 40, no. 154, pp. 69–74, 2016.
View at: Publisher Site | Google Scholar
K. Krumova and G. Cosa, “Chapter 1: overview of reactive oxygen species,” in Singlet Oxygen: Applications in Biosciences and Nanosciences, Volume 1, pp. 1-2, 2016.
View at: Publisher Site | Google Scholar

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