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.

Enhanced photocatalytic activity of Co doped ZnO nanodisks and nanorods prepared by a facile wet chemical method

Abstract: Cobalt doped ZnO nanodisks and nanorods were synthesized by a facile wet chemical method and well characterized by X-ray diffraction, field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM) with energy dispersive X-ray spectroscopy, photoluminescence spectroscopy, Raman spectroscopy and UV-visible absorption spectroscopy. The photocatalytic activities were evaluated for sunlight driven degradation of an aqueous methylene blue (MB) solution. The results showed that Co doped ZnO nanodisks and nanorods exhibit highly enhanced photocatalytic activity, as compared to pure ZnO nanodisks and nanorods. The enhanced photocatalytic activities of Co doped ZnO nanostructures were attributed to the combined effects of enhanced surface area of ZnO nanodisks and improved charge separation efficiency due to optimal Co doping which inhibit recombination of photogenerated charge carriers. The possible mechanism for the enhanced photocatalytic activity of Co doped ZnO nanostructures is tentatively proposed.

Effect of Particle Size and Phase Composition of Titanium Dioxide Nanoparticles on the Photocatalytic Properties

Abstract: Titanium dioxide (TiO2) nanoparticles were prepared by the oxidation of titanium tetrachloride (TiCl4) in a diffusion flame reactor. The average diameter of particles was 15–30 nm and mass fraction of anatase ranged from 40% to 80%. Effects of particle size and phase composition of those TiO2 nanoparticles on photocatalytic properties such as decomposition of methylene blue, bacteria and ammonia gas were investigated. The degree of decomposition of methylene blue by the TiO2 nanoparticles under the illumination of the black light was directly proportional to the anatase mass fraction, but inversely to the particle size. The decomposition of bacteria and ammonia gas by the TiO2 nanoparticles under the illumination of the fluorescent light showed the same trend as in the case of the methylene blue.

ESR investigation into the effects of heat treatment and crystal structure on radicals produced over irradiated TiO2 powder

Abstract: Electron spin resonance measurements were carried out at 77 K under irradiation for anatase TiO 2 powders treated by heating at various temperatures in the air. For the untreated powder photoproduced holes were trapped at the surface forming Ti 4+ O − Ti 4+ OH − radicals, while, for the heated powder, they were trapped as Ti 4+ O 2− Ti 4+ O − radicals at the surface. Photoproduced electrons were trapped as Ti 3+ at the desorption of surface hydroxyl groups and the change in the surface accompanied by the crystalline growth. No photoproduced radicals were detected for rutile TiO 2 powder, which may explain the low photocatalytic activity of this crystalline structure.

Atomically dispersed antimony on carbon nitride for the artificial photosynthesis of hydrogen peroxide

Abstract: Artificial photosynthesis offers a promising strategy to produce hydrogen peroxide (H2O2)—an environmentally friendly oxidant and a clean fuel. However, the low activity and selectivity of the two-electron oxygen reduction reaction (ORR) in the photocatalytic process greatly restricts the H2O2 production efficiency. Here we show a robust antimony single-atom photocatalyst (Sb-SAPC, single Sb atoms dispersed on carbon nitride) for the synthesis of H2O2 in a simple water and oxygen mixture under visible light irradiation. An apparent quantum yield of 17.6% at 420 nm together with a solar-to-chemical conversion efficiency of 0.61% for H2O2 synthesis was achieved. On the basis of time-dependent density function theory calculations, isotopic experiments and advanced spectroscopic characterizations, the photocatalytic performance is ascribed to the notably promoted two-electron ORR by forming μ-peroxide at the Sb sites and highly concentrated holes at the neighbouring N atoms. The in situ generated O2 via water oxidation is rapidly consumed by ORR, leading to boosted overall reaction kinetics. Hydrogen peroxide is an interesting target for artificial photosynthesis, although its actual production via the two-electron oxygen reduction reaction remains limited. Now, a carbon nitride-supported antimony single atom photocatalyst has been developed with a superior performance for this process.

Photodegradation of bisphenol A by highly stable palladium-doped mesoporous graphite carbon nitride (Pd/mpg-C3N4) under simulated solar light irradiation

Abstract: Palladium modified mesoporous graphitic carbon nitride polymer (Pd/mpg-C 3 N 4 ) was fabricated and used for the degradation of bisphenol A (BPA) in water. Doping Pd on the surface of mpg-C 3 N 4 enhanced the light absorbance in the range of UV–vis region. Most of the embedded Pd was present as Pd 0 and could act as electron traps and facilitate the separation of photogenerated holes and electron pairs. As a result, the photocatalytic performance was improved significantly. The reaction rate constant ( k obs ) increased with the Pd loading on the surface of mpg-C 3 N 4 and the maximum was achieved with 1.50% Pd. Almost 100% of BPA (20 mg L −1 ) was photodegraded by the solids of 0.5 g L −1 Pd/mpg-C 3 N 4 after irradiation with simulated solar light for 360 min. The Pd/mpg-C 3 N 4 exhibited very stable and high efficient photocatalytic activity to BPA in a wide range of pH 3.08–11.00. It also displayed high photocatalytic activity without photocorrosion after reuse for many times. Hydroxyl radicals, photogenerated holes, and superoxide radical species were responsible for the photodegradation while the superoxide radical species were more predominant in the Pd/mpg-C 3 N 4 reaction system.