Visible spectrum

Herein, MoS2-ZnO heterostructure nanorods were hydrothermally synthesized and characterized in detail using several compositional, optical, and morphological techniques. The comprehensive characterizations show that the synthesized MoS2/ZnO heterostructure nanorods were composed of wurtzite hexagonal phase of ZnO and rhombohedral phase of MoS2. The synthesized MoS2/ZnO heterostructure nanorods were used as a potent photocatalyst for the decomposition of methylene blue (MB) dye under natural sunlight. The prepared MoS2/ZnO heterostructure nanorods exhibited ~97% removal of MB in the reaction time of 20 min with the catalyst amount of 0.15 g/L. The kinetic study revealed that the photocatalytic removal of MB was found to be in accordance with pseudo first-order reaction kinetics with an obtained rate constant of 0.16262 min−1. The tremendous photocatalytic performance of MoS2-ZnO heterostructure nanorods could be accredited to an effective charge transportation and inhibition in the r...

In this research, Ag-Ag3PO4/Cellulose aerogel composite was synthesized using hydrothermal reduction and freeze-drying methods. By combining the photocatalytic activity of the semiconductor Ag-Ag3PO4 and cellulose aerogel synthesized from agricultural waste sources, the synthesized Ag-Ag3PO4/Cellulose aerogel composite has overcome the disadvantages of pure Ag3PO4 and significantly improved the photocatalytic activity. Structural characteristics, morphology, surface area of the materials were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), N2 adsorption-desorption and UV–vis diffuse reflectance spectroscopy (UV-vis DRS) methods. From the obtained results, composite has narrow bandgap energy (2.275 eV) and excellent catalytic performance in the photodegradation of dye pollutants (99% MB and 77% RY 145 degraded after 4 h, and only a minor change in the efficiency observed after four consecutive tests). It  demonstrates the development of new catalysts made fro...

The effects of visible light, from short to long wavelengths, on the retina were investigated functionally and histologically. The left eyes of Sprague–Dawley albino rats (6-weeks old, n = 6 for each wavelength) were exposed to seven narrow-band wavelengths (central wavelengths, 421, 441, 459, 501, 541, 581, and 615 nm) with bandwidths of 16 to 29 nm (half bandwidth, ±8–14.5 nm) using a xenon lamp source with bandpass filters at the retinal radiant exposures of 340 and 680 J/cm2. The right unexposed eyes served as controls. Seven days after exposure, flash electroretinograms (ERGs) were recorded, and the outer nuclear layer (ONL) thickness was measured. Compared to the unexposed eyes, significant reductions in the a- and b-wave ERG amplitudes were seen in eyes exposed to 460-nm or shorter wavelengths of light. The ONL thickness near the optic nerve head also tended to decrease with exposure to shorter wavelengths. The decreased ERG amplitudes and ONL thicknesses were most prominent ...

ABSTRACT Visible light-activated sulfur-doped g-C3N4 photocatalysts were successfully synthesized using thiourea as sulfur source. The obtained photocatalysts were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microcopy, ultraviolet-visible diffuse reflection spectroscopy, X-ray photoelectron spectroscopy, photoluminescence spectroscopy and transient photocurrent response. The sulfur-doped g-C3N4 photocatalysts show beneficial effects on visible light absorption, electron-hole pair generation and separation. The sulfur species doped in the samples was identified as S2- to replace N atoms in the g-C3N4 framework. The photocatalytic activities of the sulfur-doped g-C3N4 under visible light were evaluated by hydrogen evolution from water splitting in aqueous solution containing methanol. The sulfur-doped g-C3N4 photocatalyst showed the highest photocatalytic performance with H-2 evolution rate of 12.16 mu mol h(-1), about 6 times higher than un-doped g-C3N4. It can be concluded that the sulfur species play a vital role and act as active sites in the photocatalytic reaction. This novel sulfur-doped g-C3N4 can be potentially used in energy and environmental applications. (c) 2013 Elsevier Ltd. All rights reserved.

In the present study, we synthesized several high-surface area V2O5/TiO2–SiO2 catalysts (vanado titanium silicate, VTS). The synthesized materials are characterized by PXRD, FE-SEM/EDAX, TEM, BET-surface area, FT-IR, UV-Vis, XPS, fluorescence and photocatalytic studies.

The creation of photocatalysts with controlled facets has become an important approach to enhance their activity. However, how the formation of heterojunctions on exposed facets could affect their photocatalytic performance ranking had not yet been investigated. In this study, Cu2O@TiO2 core-shell structures were created, and Cu2O/TiO2 p-n heterojunctions were formed on various exposed facets of Cu2O cubes, Cu2O cuboctahedra, and Cu2O octahedra, respectively. These Cu2O@TiO2 polyhedra demonstrated an enhanced photocatalytic degradation effect on Methylene Blue (MB) and 4-nitrophenol (4-NP) under visible light illumination, because of the enhanced charge carrier separation by the formation of Cu2O@TiO2 p-n heterojunctions. It was further found that their photocatalytic performance was also facet-dependent as pure Cu2O polyhedra, while the photocatalytic performance ranking of these Cu2O@TiO2 polyhedra was different with that of their corresponding Cu2O polyhedron cores. By the combin...

An improved photocatalytic activity of semiconductor materials using incorporation of the noble metals such as Ag, Au, and Pt is a promising technology. In this study, Ag nanoparticle-TiO2 nanotube structures (Ag-TNTs) have been investigated as a photocatalyst in different irradiation conditions using different characterization techniques. The results indicate that Ag nanoparticles dispersed uniformly on the TNTs’ surface without any change in TNTs’ morphology. In addition, Ag-TNTs exhibited lower photoactivity than the TNTs under UV irradiation. In contrast, Ag-TNTs increased the photoactivity in comparison with TNTs and the photocatalytic performance under sunlight irradiation. These phenomena could be contributed to the appearance of Ag nanoparticles on the nanotube surface.

A palladium (Pd) doped mesoporous titanium dioxide (TiO2) photocatalyst was used to produce hydrogen (H2) via water splitting under both near-UV and visible light. Experiments were carried out in the Photo-CREC Water-II Reactor (PCW-II) using a 0.25 wt% Pd-TiO2 photocatalyst, initial pH = 4 and 2.0 v/v% ethanol, as an organic scavenger. After 6 h of near-UV irradiation, this photocatalyst yielded 113 cm3 STP of hydrogen (H2). Furthermore, after 1 h of near-UV photoreduction followed by 5 h of visible light, the 0.25 wt% Pd-TiO2 photocatalyst yielded 5.25 cm3 STP of H2. The same photocatalyst, photoreduced for 24 h under near-UV and subsequently exposed to 5 h of visible light, yielded 29 cm3 STP of H2. It was observed that the promoted redox reactions led to the production of hydrogen and by-products such as methane, ethane, ethylene, acetaldehyde, carbon monoxide, carbon dioxide and hydrogen peroxide. These redox reactions could be modeled using an “in series-parallel” reaction net...

We present a simplistic, ultrafast, and facile hydrothermal deposition of ternary Cu2SnS3 nanoparticles (CTS NPs). The fabricated CTS NPs show superior antimicrobial and photocatalytic activities. In the presence of UV-Visible illumination, methylene blue (MB) dye was studied for photocatalytic dye degradation activity of CTS NPs. Excellent efficiency is shown by incorporating CTS NPs to degrade MB dye. There is a ~95% decrease in the absorbance peak of the dye solution within 120 min. Similarly, CTS NPs tested against three bacterial strains, i.e., B. subtilis, S. aureus, P. vulgaris, and one fungal strain C. albicans, defining the lowest inhibitory concentration and zone of inhibition, revealed greater antimicrobial activity. Hence, it is concluded that the CTS NPs are photocatalytically and antimicrobially active and have potential in biomedicine.

Herein we demonstrate brief investigation results of photoelectrochemical performance of TiO2 nanotube (NT) based photoelectrode incorporated with V2O5 nanopaerticles (NP). Photoelectrodes were composed of TiO2 NTs with a diameter of 100 nm and length of 8μm,that were prepared by electrochemical anodization process at 35V in a formamade based electrolyte. The V2O5 nanoparticles were formed on the walls of the TiO2 NTs by deep coating technique with an average size of ∼5-10 nm. The V2O5 NP incorporated TiO2 NTs show superior light absorption properties in the visible light region up to ∼600 nm compared to the pristine TiO2NTs. It was found that V2O5 NPs formed vanadium impurities within TiO2 NTs which in its turn ceated acceptor levels of V3+ ions in the TiO2 NTs located deep in the forbidden band gap and provided additional absorption properties of visible light. These impurity levels also provide fast recombination sites of electrons and holes formed by photon excitation.

Formation of ZnO/CuS heterostructure through a simple wet-chemical method leads to a type-II semiconductor. The heterojunction between these two moieties leads to the separation of electron–hole pairs, which further enhances the photocatalytic efficiency of ZnO.

ABSTRACT Aim of this work is the synthesis of titanium-based photocatalysts co-doped with both C and N, exhibiting improved photocatalytic activity under visible light irradiation. The preparation of the catalysts consists of a two step process: during the first one, the synthesis of the catalyst doped with nitrogen has been carried out, whereas in the second step carbon has been introduced in different amounts. The photocatalytic activity has been evaluated in the gas phase reaction of NOx abatement under visible light irradiation. The characterization has been carried out by N-2 physisorption, TPO (temperature programmed oxidation), DRS (diffuse reflectance spectroscopy) and XPS (X-ray Photoelectron Spectroscopy) in order to investigate both structural and physico-chemical features of the samples and their correlation with the catalytic activity. An effective promotion effect of the dopants has been observed; in particular, the synergic co-presence of both N and C produced a significant narrowing of the TiO2 band gap with the consequent extension of the photocatalytic activity towards the visible part of the light spectrum.

Mustard spinach plants were grown in mercury-spiked and contaminated soils collected in the field under controlled laboratory conditions over a full growth cycle to test if vegetation grown in these soils has discernible characteristics in visible/near-infrared (VNIR) spectra. Foliar Hg concentrations (0.174-3.993ppm) of the Mustard spinach plants were positively correlated with Hg concentration of soils and varied throughout the growing season. Equations relating foliar Hg concentration to spectral reflectance, its first derivative, and selected vegetation indices were generated using stepwise multiple linear regression. Significant correlations are found for limited wavelengths for specific treatments and dates. Ratio Vegetation Index (RVI) and Red Edge Position (REP) values of plants in Hg-spiked and field-contaminated soils are significantly lower relative to control plants during the early and middle portions of the growth cycle which may be related to lower chlorophyll abundan...