Study On Photocatalytic Selective Oxidation And Reduction Of Organics Over Metal Sulfides

Metal sulfides were synthesized by different methods, studying photocatalytic selective oxidation and reduction of organic compounds under visible light. Photocatalysts were characterized by X-ray powder diffraction, UV-Vis spectroscopy, scanning electron microscopy, transmission electron microscopy, N2 adsorption desorption, fluorescence spectra, photocurrent, electrochemical impedance spectroscopy, X-ray photoelectron energy spectrum and so on, analyzing physical structure, optical properties, morphology, specific surface area, pore structure, the efficiency separation of photogenerated electron-hole paris and surface composition of the photocatalyst. BN/In2S3 composite photocatalytic results for selective oxidation of aromatic alcohol to the corresponding aldehyde under visible light show that 7% BN/ In2S3 composite exhibits the best photocatalytic activity. BN nanosheet is negatively charged after ultrasonic treatment, so it can quickly transfers with positive photogenerated holes, which improves efficiency separation of photogenerated electron-hole pairs and inhibits its recombination, thereby enhancing the photocatalytic activity. Another metal sulfide Cd S synthesized through solid-state reaction at room temperature, which was tested the photocatalytic activity by the way of photocatalytic oxidation of p-methoxybenzyl alcohol(p MBA) and reduction of nitrobenzene(NB) under visible light in one reaction system at N2 atmosphere. The conversions of p MBA and NB are 92.2% and 93.3%, respectively, and the yields of p-methoxybenzaldehyde(p MBAD) and aniline(AL) are 83.5% and 62.3%,respectively after under visible light illumination for 4 h. By capturing experiments infer the possible reaction mechanism, photogenerated hole direct oxides aromatic alcohols to aromatic aldehydes and photoinduced electron combining with proton H reduces nitrobenzene into aniline. In addition, Cd S nanoparticle prepared through hydrothermal method, the photocatalytic activity was tested photocatalytic selective redox of p MBA in one reaction system under visible light of N2 atmosphere. The reaction system not only can achieve the oxidation p MBA to p MBAD but also cancome true reduction p MBA to p-methyl anisole(p MA) with a disproportionate process. Furthermore, the yields of p MBAD and p MA can achieve the theoretical value approximately. The effects of different aromatic alcohols and different solvents on the photocatalytic activity were also studied. Metal sulfide is a kind of efficient and stable photocatalyst, the application of photocatalytic oxidation and reduction organic compounds has been idling for the first leg, provides a mild and green reaction routes for organic synthesis, broaden the scope of application of photocatalysis.