Photocatalysis

About: Photocatalysis is a research topic. Over the lifetime, 67088 publications have been published within this topic receiving 2145233 citations. The topic is also known as: photocatalyst.

Study on the separation mechanisms of photogenerated electrons and holes for composite photocatalysts g-C3N4-WO3

Abstract: The separation mechanisms of photogenerated electrons and holes for composite photocatalysts have been a research focus. In this paper, the composite g-C 3 N 4 -WO 3 photocatalysts with different main parts of C 3 N 4 or WO 3 were prepared by ball milling and heat treatment methods. The photocatalytic performance was evaluated by degradation of methylene blue (MB) and fuchsin (BF) under visible light illumination. The photocatalyst was characterized by X-ray powder diffraction (XRD), UV–vis diffuse reflection spectroscopy (DRS), transmission electron microscopy (TEM) and Brunauer–Emmett–Teller (BET) methods. The separation mechanisms of photogenerated electrons and holes of the g-C 3 N 4 -WO 3 photocatalysts were investigated by electron spin resonance technology (ESR), photoluminescence technique (PL), and determination of reactive species in the photocatalytic reactions. When the main part of the g-C 3 N 4 -WO 3 photocatalyst is WO 3 (namely g-C 3 N 4 /WO 3 ), the transport process of the photogenerated electrons and holes adopts the generic band–band transfer. Meanwhile, g-C 3 N 4 is covered by WO 3 powder, and the role of g-C 3 N 4 can not be played fully. The photocatalytic activity of the photocatalyst is not obviously increased. However, when the primary part of the WO 3 -g-C 3 N 4 photocatalyst is g-C 3 N 4 (namely WO 3 /g-C 3 N 4 ), the migration of photogenerated electrons and holes exhibits a typical characteristic of Z-scheme photocatalyst, and the photocatalytic activity of the photocatalyst is increased greatly.

Effects of calcination on the photocatalytic properties of nanosized TiO2 powders prepared by TiCl4 hydrolysis

Abstract: The ultra fine nanosized TiO2 photocatalysts in the anatase, rutile, and both phases were prepared by the hydrolysis of TiCl4 solution The resulting materials have been characterized by HREM, XRD, BET and UV–VIS absorption spectroscopy The photoactivity, effective degradation, and the selectivity for complete mineralization of these catalysts were tested in the photocatalytic degradation of phenol For this reaction, the quantum-sized catalyst particles (4 nm) in the anatase phase shows the highest selectivity, the concentrations of p-benzoquinone and hydroquinol as the photocatalytic products were at very low level However, the selectivity of the quantum-sized crystallites in the rutile phase was not improved in comparison with that of catalysts which bandgap corresponding bulk rutile HREM micrographs show the quantum-sized catalysts were crystallized partially or many defects occurred on their crystal planes, they are responsible for their relative low photoactivity Calcination is an effective treatment to increase the photoactivity of nanosized TiO2 photocatalysts resulting from the improvement of crystallinity Mixtures of both phases exhibit higher photoactivity as well as effective degradation in comparison with pure anatase or rutile catalysts To the best of our knowledge, we are first to report that the quantum-sized TiO2 crystallite exhibit high selectivity for complete mineralization in the photocatalytic degradation of phenol solution

Enhanced Rates of Photocatalytic Degradation of an Azo Dye Using SnO2/TiO2 Coupled Semiconductor Thin Films.

Abstract: We present here for the first time the results from electrochemically assisted photocatalytic experiments using coupled TiO{sub 2}/SnO{sub 2} semiconductor thin films in the degradation of textile dye effluent. We show that by using such a system the oxidative efficiency of photocatalytic semiconductor systems in degrading a commercial azo dye such as Acid Orange 7 (AO7) can be improved. The results presented here on the decolorization of the azo dye AO7 represents a major step forward in the development of new advanced oxidation processes for the treatment of such industrial waste. The improved charge separation as a result of coupling two semiconductor systems with different energy levels and the applied anodic bias is responsible for the enhancement in the rate of photocatalytic degradation. 20 refs., 6 figs.

Improved photocatalytic activity and characterization of mixed tio2/sio2 and tio2/al2o3 materials

Abstract: The characterization of mixed oxides of TiO2/SiO2 and TiO2/Al2O3 prepared by sol−gel methods is described. Application of the TiO2/Al2O3 material for the photocatalytic decomposition of salicylic acid gave improved activity relative to TiO2-only materials. The photocatalytic activity of TiO2/SiO2, TiO2/Al2O3, and TiO2 toward the photocatalytic decomposition of phenol demonstrated the enhancement of local TiO2 sites on TiO2/SiO2 materials relative to the other materials. The characterization of the catalysts indicates that the TiO2/SiO2 materials consist of matrix-isolated TiO2 quantum particles, while the TiO2/Al2O3 materials do not.

Polymeric g-C3N4 Coupled with NaNbO3 Nanowires toward Enhanced Photocatalytic Reduction of CO2 into Renewable Fuel

Abstract: Visible-light-responsive g-C3N4/NaNbO3 nanowires photocatalysts were fabricated by introducing polymeric g-C3N4 on NaNbO3 nanowires. The microscopic mechanisms of interface interaction, charge transfer and separation, as well as the influence on the photocatalytic activity of g-C3N4/NaNbO3 composite were systematic investigated. The high-resolution transmission electron microscopy (HR-TEM) revealed that an intimate interface between C3N4 and NaNbO3 nanowires formed in the g-C3N4/NaNbO3 heterojunctions. The photocatalytic performance of photocatalysts was evaluated for CO2 reduction under visible-light illumination. Significantly, the activity of g-C3N4/NaNbO3 composite photocatalyst for photoreduction of CO2 was higher than that of either single-phase g-C3N4 or NaNbO3. Such a remarkable enhancement of photocatalytic activity was mainly ascribed to the improved separation and transfer of photogenerated electron–hole pairs at the intimate interface of g-C3N4/NaNbO3 heterojunctions, which originated from the...