Electron-parking engineering assisted ZnIn2S4/Mo2TiC2-Ru photocatalytic hydrogen evolution for efficient solar energy conversion and storage

The electron utilization efficiency in photocatalytic hydrogen evolution (PHE) is crucial for solar energy conversion and storage. Prolonged lifetime and effective use of accumulated electrons based on the storage-release behavior is a potential strategy to regulate the electronic utilization efficiency. Herein, this study utilized Mo2TiC2-Ru as the "electron-parking" to construct a ZnIn2S4/Mo2TiC2-Ru photocatalyst. The ZnIn2S4/Mo2TiC2-Ru exhibits a visible light-driven PHE rate of 5.72 mmol·g-1·h-1, and maintains a PHE rate of ~1.67 mmol·g-1·h-1 under dark conditions. The photogenerated electrons could be directionally stored in Mo2TiC2-Ru to create an electron-rich environment, this can inhibit backflow and recombination of electrons, and could regulate the water dissociation and hydrogen adsorption kinetics. Importantly, the stored electrons could release in the dark, increasing the quantity of electrons and overcoming intermittent sunlight and regional environmental influences. This work provides insights and references for the development of capacitive cocatalysts with an "electron-parking" engineering for efficient and sustained PHE reactions.