All-solid-state Z-scheme Pt/ZnS-ZnO heterostructure sheets for photocatalytic simultaneous evolution of H2 and O2

Abstract

The simultaneous production of the hydrogen and oxygen for photocatalytic water splitting still remains a critical challenge because O2 release from semiconductor catalysts is an extremely difficult. Herein, we design and synthesize a novel ZnS-ZnO heterostructure sheets by combining solid-state Z-scheme for photocatalytic O2 and H2 evolution. Electron spin resonance result confirms that a solid-state Z-scheme is successfully introduced into the ZnS-ZnO heterostructure. Thanks to the rapid separation and migration of photoinduced electron/hole according to the Z-scheme mechanism, ZnS-ZnO heterostructure exhibits efficient H2 evolution without using any sacrificial agent, far beyond the comparative values reported by currently ZnS/ZnO-based photocatalysts. Especially, the as-synthesized photocatalyst presents the ability of O2 evolution for pure water splitting using Pt as cocatalyst, which is too difficult to be realized for previously reported ZnO/ZnS-based photocatalysts. Therefore, this work presents a new idea to design other semiconductor photocatalysts for simultaneous H2 and O2 evolution.