Journal of Nanomaterials

A hierarchical structure of TiO₂ nanorod/MnO₂ ultrathin nanosheet core/shell nanocomposite arrays on a conductive substrate has been prepared by two facile steps of hydrothermal reaction and annealing progress, which serving as electrodes present great potential application for high-performance supercapacitors. By adjusting the concentration of precursor aqueous solution, it can be found that the thickness of the MnO₂ shell in the as-designed hierarchical electrode material can be facilely controlled. By comparison, the obtained TiO₂ nanorod/MnO₂ ultrathin nanosheet as an electrode material can achieve the best electrochemical performance in terms of the area-specific capacitance up to 34.79 mF/cm² from the cyclic voltammetry (CV) test at the scan rate of 5 mV/s. Furthermore, the composited electrode has also demonstrated good stability, with the capacitance retention rate of about 91% through the cycle experiment test after 1000 cycles.

In this study, the porous activated carbon fiber (ACF) is prepared by viscose fiber, and Fe₃O₄ coating is deposited on the surface of ACF through in situ hybridization to prepare carbon/magnetic electromagnetic (EM) wave absorption materials. Compared with pure Fe₃O₄ and ACF, the EM wave absorption rate is improved. When the solubility of FeCl₃ is 2 mol/L and the thickness of the prepared ACF–Fe₃O₄(3) EM wave absorption material is 3 mm, the EM wave loss at 10 GHz reaches −44.3 dB and effective EM wave absorption bandwidths ( dB and  dB) reached 4.8 GHz (8.8–13.6 GHz) and 1.1 GHz (9.3–10.4 GHz), respectively. The prepared ACF-based composite material has a light structure and strong absorption bandwidth. Findings can provide references for the research on other EM wave-absorbing materials.

The self-assembling is a spontaneous progression through which objects of nanophase/molecules materialize into prepared collections. Several biomolecules can interact and assemble into highly structured supramolecular structures, for instance, proteins and peptides, with fibrous scaffolds, helical ribbons, and many other functionalities. Various self-assembly systems have been established, from copolymers in blocks to three-dimensional (3D) cell culture scaffolds. Another advantage of self-assembly is its ability to manage a large variety of materials, including metals, oxides, inorganic salts, polymers, semiconductors, and various organic semiconductors. The most basic self-assembly of 3D nanomaterials is three primary forms of nanostructured carbon-based materials that perform a critical role in the progress of modern nanotechnologies, such as carbon nanotubes (CNTs), graphene, and fullerene. This review summarized important information on the 3D self-assembly nanostructure, such as peptide hydrogel, graphene, carbon nanotubes (CNTs), and fullerene for application in gene delivery, cancer therapy, and tissue engineering.

Synthesizing nanoparticles with the less environmentally malignant approach using plant extract is of great interest; this is because most of the chemical approaches can be very costly, toxic, and time-consuming. Herein, we report the use of Acacia senegal leaf extracts to synthesize silver nanoparticles (AgNPs) using an environmentally greener approach. Silver ions were reduced using the bioactive components of the plant extracts with observable colour change from faint colourless to a brownish solution as indication of AgNP formation. The structural properties of the as-synthesized AgNPs were characterized using powder X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and UV-Vis absorption spectrum. Antimicrobial assessment of the as-synthesized AgNPs was explored on some strains of gram-positive and gram-negative bacteria. The obtained results indicate that the as-synthesized AgNPs are pure crystallite of cubic phase of AgNPs, fairly dispersed with a size range of 10–19 nm. The AgNPs were found to be small in size and exhibit significant antibacterial activities, suggesting that the as-synthesized AgNPs could be used in the pharmaceutical and food industries as bactericidal agents.

A carbon nanotubes/graphene composite is grown on nickel foil without additional catalysts by one-step ambient pressure chemical vapor deposition (CVD). Next, the carbon nanotubes/graphene composite is modified by radio frequency (RF) nitrogen plasma. Finally, to improve its initial coulombic efficiency/electrochemical stability, lower potential during the charge process (coin cell), and boost potential during the discharge process (lithium-ion battery), alumina is deposited onto the N-doped carbon nanotubes/graphene composite by RF magnetron sputtering at different power levels and periods of time. The charge specific capacity (597 mAh/g) and initial coulombic efficiency (81.44% > 75.02% for N-doped carbon nanotubes/graphene) of Al₂O₃/N-doped CNTs/graphene for the coin cell reached a maximum at the best sputtering condition ( and ). Al₂O₃/N-doped CNTs/graphene (the best sputtering condition) exhibits higher initial coulombic efficiency (79.8%) compared with N-doped CNTs/graphene (initial coulombic efficiency: 74.3%) for the lithium-ion battery. Furthermore, the achievement fraction (about 70%) of full charge capacity (coin cell) for Al₂O₃/N-doped carbon nanotubes/graphene (the best sputtering condition) is higher than that (about 30%) for N-doped carbon nanotubes/graphene at a voltage lower than about 0.25 V. Moreover, it also shows a little higher electrochemical stability (coin cell) of charge capacity for Al₂O₃/N-doped carbon nanotubes/graphene (the best sputtering condition) in comparison with N-doped carbon nanotubes/graphene and Al₂O₃/N-doped CNTs/graphene (the best sputtering condition) exhibits better cyclic stability (lithium-ion battery) of discharge capacity compared with N-doped CNTs/graphene.

Silver nanoparticles (Ag NPs) have become one of the current research hotspots and are used in many fields such as electrochemistry, energy, bioanalysis, and environmental monitoring, especially in the field of antibacterial research. In this study, we investigated the effect of properties of Ag NPs coated with polar materials. Ag NPs covered by a dispersant that was triethylene glycol monoethyl ether was stable and conquered the aggregation of Ag NPs. The effect of the dispersant on biocompatibility was explored through interaction experiments between Ag NPs and DNA sequence. The coated Ag NPs could adsorb DNA, and the fluorescence of FAM-DNA could be quenched by Ag NPs. The adsorption and desorption experiments of DNA showed that the order of DNA functional groups on the interaction process was phosphate>T>C>A>G. Moreover, we selected marine pathogenic bacteria to test the antibacterial effect of Ag NPs coated with a polar dispersant. The polar material had a certain inhibitory effect on the antibacterial activity of Ag NPs. However, small molecules such as bases could interact on the surface Ag NPs and release Ag⁺ to perform the antibacterial activity. The results could contribute to the further application of Ag NPs.