Au decorated hollow ZnO@ZnS heterostructure for enhanced photocatalytic hydrogen evolution: The insight into the roles of hollow channel and Au nanoparticles

A new type of Au nanoparticles (NPs) decorated hollow flower-like ZnO@ZnS (HZOS) heterostructure (HS) is elaborately designed as efficient photocatalyst for water splitting application. The optimal Au decorated HZOS exhibits a high hydrogen generation rate of 569.81 mu mol/h (10 mg of catalyst), which is 345, 374 and 11 times higher than that of pristine ZnO (1.65 mu mol/h), ZnS (1.52 mu mol/h) and ZnO@ZnS (51.7 mu mol/h), respectively. Furthermore, its apparent quantum efficiency reaches to 25.47% at the wavelength of 365 nm. The significantly enhanced Hy evolution can be attributed to the synergistic effects from the hollow channel structure and the deposited Au NPs. The hollow channel creates a new migration pathway where charge carriers can transfer towards the hollow channel in addition to the outer surface of the photocatalyst, thus significantly reducing the migration distance of charge carriers, suppressing the recombination of photogenerated electrons and holes, and reducing their transfer resistance. The decoration of Au NPs at the interface between ZnO and ZnS not only facilitates the directional migration of charge carriers because of the formation of Schottky barrier, but also works as electron shuttles to form a Z-scheme transfer process, effectively promoting the separation and migration of charge carriers.