Unassisted photoelectrochemical hydrogen peroxide production over MoOx-supported Mo on a Cu3BiS3 photocathode

Abstract

Hydrogen peroxide (H₂O₂) represents a valuable chemical compound and promising energy source due to its high energy density, comparable with that of compressed H₂. However, its production predominantly relies on an energy-intensive process. In this study, we present an efficient strategy for producing H₂O₂ through a photoelectrochemical (PEC) approach, which involves a 2e⁻-mediated oxygen reduction reaction, integrating Mo-anchored MoO_x with a Cu₃BiS₃-based photocathode. The MoO_x-supported Mo improves the adsorption strength of peroxide species and facilitates electron transport, resulting in outstanding activity toward H₂O₂ production. Consequently, the resulting Cu₃BiS₃-based photocathode demonstrates significantly enhanced performance, achieving a photocurrent density of 5.21 mA cm⁻² at 0.35 V versus the reversible hydrogen electrode (RHE), a high onset potential of 0.9 V_RHE, and 97% selectivity toward H₂O₂. Additionally, we successfully implemented an unassisted PEC–PEC coplanar system by coupling a Cu₃BiS₃-based photocathode with a perovskite-based photoanode, achieving a solar-to-chemical conversion efficiency of 1.46%.