Bias-free photoelectrochemical H2O2 production with a solar-to-fuel conversion efficiency of 2.33%

Abstract

A promising approach to H₂O₂ production that combines renewable solar energy with earth-abundant water and air could lead to scalable economic benefits. While many breakthroughs have been made in recent years in the research of solar-driven H₂O₂ production, the solar-to-fuel conversion efficiency (STF) remains unsatisfactory. Here, we demonstrate a bias-free photoelectrochemical (PEC) device for efficient solar-driven overall H₂O₂ production by coupling a magnesium-doped tantalum nitride (Mg:Ta₃N₅) photoanode for the water oxidation half-reaction with an ordered mesoporous carbon (CMK-3) loaded carbon cloth (CC) cathode for the oxygen reduction half-reaction. Taking advantage of the wide visible-light absorption range and proper band positions of the Mg:Ta₃N₅ photoanode for overall H₂O₂ production and the high activity and selectivity of the CC/CMK-3 cathode, a record STF of 2.33% is achieved with the assembled Mg:Ta₃N₅‖Nafion‖CC/CMK-3 PEC device for bias-free H₂O₂ production. The demonstration of an efficient bias-free PEC device with a simple device structure represents a breakthrough in the production of H₂O₂ from solar energy.