Redox-Based Visible-Light-Driven Z-Scheme Overall Water Splitting with Apparent Quantum Efficiency Exceeding 10%

Abstract

Summary For mimicry of natural photosynthesis, particulate-based Z-scheme overall water splitting (ZOWS) free of external bias is intriguing for hydrogen production, but it commonly confronts low efficiency with the huge challenge of charge transfer and separation. Here we report an assembly of unprecedentedly efficient ZOWS system with apparent quantum efficiency (AQE) of 10.3% at 420 nm using [Fe(CN)6]3−/[Fe(CN)6]4− as redox mediator. The breakthrough of AQE is mainly ascribed to an effective cocatalyst strategy that significantly promotes charge transfer and surface catalysis. Meanwhile, the metallic Au cocatalyst is first revealed to favor electron transfer from BiVO4 to [Fe(CN)6]3− shuttle ions, and site-selective deposition of Au and CoOx dual cocatalysts on the corresponding electron-rich {010} and hole-rich {110} facets of BiVO4 is crucial for promotion of water oxidation. This work highlights the importance of the cocatalyst strategy as well as site-selective deposition in accelerating charge separation and surface catalysis of artificial photocatalyst for enhanced solar-to-chemical energy conversion.