Ethylenediamine-assisted Solvothermal Synthesis Of Cd_xZn_1-xS Solid Slutions And Their Photocatalytic Reduction For Nitrobenzene

Semiconductor nanostructures have unique optical and photocatalytic properties due to their volume effect, surface effect, quantum size effect, and dielectric effect. Photocatalysis, which developed in 1970s, is a "green", high efficient technique. They have practical applications in environmental cleaning, energy regeneration and organics synthesis. To make full use of solar energy, designing photocatalysts with high efficiency under visible-light irradiation is necessary. In solvothermal synthesis, the solvent has a great influence on the product's phase, morphology, microstructure, and chemical properties further.In this dissertation, modified photocatalysts were explored to realize the photocatalytic activities'enhancement under visible-light irradiation. We prepared CdxZn(1-x)S solid solutions in ethylenediamine (en)-water mixed solvent by modulating the added CdCl2·2.5H2O and ZnCl2, and the effect of solvent was investigated too. Photocatalytic activities were systematically studied by means of photocatalytic reduction of nitrobenzene. The summary is described as follows:A series of one-dimensional, hexagonal phased CdxZn(1-x)S solid solutions were successfully prepared in en-water mixed solutin by modulating the initial concentration of Cd2+ and Zn2+. Futher study showed that the products' microstructures, X-ray diffraction (XRD) patterns, energy band structures, optical properties, and specific surface areas changed with the value of x. The main phtotoreduction products were nitrosobenzene and aniline when methanol eliminated dissolved oxygen was used as the reaction medium. Cdo.73Zno.27S and ZnS showed the highest activity under visible-light and UV-light irradiation respectively, owing to the photocatalysts'microstructure, bandgap, conduction band potential, and specific surface area.We investigated the effect of solvent by praparing CdxZn(1-x)S solid solutions in pure en and water. The starting molar ratio of Cd2+/Zn2+ was controlled at 1. Results showed that en had a great influence on the products' chemical composition, microstructure, special surface area, surface adsorbed groups, energy band, and photocatalytic acivity further. Controlled experiments showed the product prepared in en-water mixed solvent exhibited the highest activity.