Light-switched electron migration routes via Co-catecholates grafted on Z-scheme Cu2O@CuO heterostructure for photoelectrochemical hydrogen evolution

Abstract

Photoelectrochemical (PEC) hydrogen evolution from water splitting is plagued by charge recombination and slow reaction kinetics. Herein, we report a scheme of Co-catecholates (Co-CAT) grafted on Z-scheme Cu₂O@CuO heterojunction for PEC hydrogen evolution. The detailed experimental and analysis results reveal that the formation of Z-scheme Cu₂O@CuO heterojunction changes the direction of electron transfer in conventional Cu₂O@CuO heterojunction. When coupled with a light field, the Z-scheme Cu₂O@CuO heterojunction photocathode acts as a photoswitch to regulate the electron migration routes to the Co-CAT catalyst. Benefiting from directional electron migration routes and the electron-rich Co-CAT catalyst, Cu₂O@CuO/Co-CAT achieves a record-high photocurrent density of −18.48mA cm⁻² at 0 V versus the reversible hydrogen electrode under 1 sun illumination compared to Cu₂O and CuO materials. It enables long-term operation for at least 100 h with only 8 % loss in photocurrent density and reaches a hydrogen generation rate of 230 μmol h⁻¹cm⁻². This work provides a novel synergistic structure of photocathode-catalyst with directional interfacial electron migration routes, and sheds light on the design of photocathodes for efficient and stable PEC hydrogen evolution.