A general interfacial-energetics-tuning strategy for enhanced artificial photosynthesis

Abstract

The demands for cost-effective solar fuels have triggered extensive research in artificial photosynthesis, yet the efforts in designing high-performance particulate photocatalysts are largely impeded by inefficient charge separation. Because charge separation in a particulate photocatalyst is driven by asymmetric interfacial energetics between its reduction and oxidation sites, enhancing this process demands nanoscale tuning of interfacial energetics on the prerequisite of not impairing the kinetics and selectivity for surface reactions. In this study, we realized this target with a general strategy involving the application of a core/shell type cocatalyst that is demonstrated on various photocatalytic systems. Particularly, this strategy was highlighted on a BiVO4 system for overall H2O2 photosynthesis. A core/shell type Ag/Pd cocatalyst was selectively deposited on the reduction facets of BiVO4, where the Ag core formed a low Schottky barrier with BiVO4 at its reduction site for enhancing charge separation and Pd shell preserved the surface kinetics and selectivity for H2O2 generation. Time-resolved spectroscopy and numerical simulations suggest the BiVO4/Ag junction enhanced the asymmetric interfacial energetics as expected. With successful interfacial energetics tuning, BiVO4 exhibits high overall H2O2 photosynthesis among inorganic photocatalysts, with an apparent quantum yield (AQY) of 3.0% and a solar-to-H2O2 conversion (STH) efficiency of 0.73% at full spectrum, as well as an AQY of 13.1% at 420 nm. The promising H2O2 generation efficiency validated our perspective on tuning interfacial energetics for enhanced charge separation and photosynthesis performance.