Photocatalytic C–C coupling reactions of benzyl alcohol for obtaining hydrobenzoin over Z-scheme ZnS/ZnIn2S4

Abstract

Solar photocatalysis provides a green and sustainable platform for the selective C–C coupling of aryl alcohols, while the selectivity of hydrobenzoin needs to be improved significantly for commercial applications. This requires the design of an economical photocatalyst to optimise the selectivity as well as the conversion of reactants. Herein, we constructed a Z-scheme ZnS/ZnIn₂S₄ heterojunction with sulphur vacancies for a photoredox system to achieve the selective C–C coupling of benzyl alcohol to obtain valuable hydrobenzoin under ambient conditions. ZnS/ZnIn₂S₄-2 as an optimal photocatalyst outperformed the reported photocatalysts to achieve a 92% yield of hydrobenzoin within 2 h. The appropriate sulphur vacancies promoted the separation and transfer of photoexcited carriers, remarkably enhancing the photocatalytic performance. Compared with pristine ZnS and ZnIn₂S₄, this heterojunction construction demonstrated an optimised electronic structure, broadened visible-light absorption, and good compatibility with environmental conditions. These extraordinary characteristics make it a promising photocatalyst for the extended synthesis of value-added hydrobenzoin.