Regulating the Electron–Hole Separation to Promote Selective Oxidation of Biomass using ZnS@Bi2S3 Nanosheet Catalyst

Abstract Herein, a new hydrothermal method has been reported for one-step controllable synthesis of ZnS@Bi2S3 nanosheets, which were used for the highly selective oxidation of biomass-derived monosaccharides to produce value-added sugar acids. The results of the photocatalytic oxidation by ZnS@Bi2S3 were compared with that by pure Bi2S3, under the same reaction conditions. Compared to pure Bi2S3, ZnS@Bi2S3 nanosheets has showed broadened band gap and improved stability. The relative band alignment indicated that the ZnS@Bi2S3 nanosheets could suppress the recombination of photogenerated charge carriers to improve the photocatalytic activity. Density functional theory (DFT) calculations were performed to investigate the photocatalytic reaction mechanism where xylose and oxygen are adsorbed on Bi2S3 (113) and ZnS (111). The xylose adsorbed on the catalytic surfaces reacted with the active free radicals generated from the photocatalytic process, and then was selectively oxidized to xylonic acid.