Defects Healing of the ZnO Surface by Filling with Au Atom Catalysts for Efficient Photocatalytic H2 Production

Abstract

Healed defects on photocatalysts surface and their interaction with plasmonic nanoparticles (NPs) have attracted attention in H-2 production process. In this study, surface oxygen vacancy (V-o) defects are created on ZnO (V-o-ZnO) NPs by directly pyrolyzing zeolitic imidazolate framework. The surface defects on V-o-ZnO provide active sites for the diffusion of single Au atoms and as nucleation sites for the formation of Au NPs by the in situ photodeposition process. The electronically healed surface defects by single Au atoms help in the formation of a heterojunction between the ZnO and plasmonic Au NPs. The formed Au/Vo-Au:ZnO-4 heterojunction prolongs photoelectron lifetimes and increases donor charge density. Therefore, the optimized photocatalysts of Au/V-o-Au:ZnO-4 has 21.28 times higher H-2 production rate than the pristine V-o-ZnO under UV-visible light in 0.35 m Na2SO4 and 0.25 m Na2SO3. However in 0.35 m Na2S and 0.25 m Na2SO3, the H-2 production rate is 25.84 mmole h(-1) g(-1). Furthermore, Au/Vo-Au:ZnO-4 shows visible light activity by generating hot carries via induced surface plasmonic effects. It has 48.58 times higher H-2 production rate than pristine Vo-ZnO. Therefore, this study infers new insight for defect healing mediated preparation of Au/Vo-Au:ZnO heterojunction for efficient photocatalytic H-2 production.