An effective integrated Cu2O photocathode to boost photoelectrocatalytic CO2 conversion

Abstract

The exploitation of high-performance photocathodes remains a key challenge to bring the feasibility of narrow bandgap semiconductors into fruition for efficient artificial photosynthesis. Herein, we show a highly efficient photocathode system consisting of a photonic crystal structure based on a cuprous oxide (Cu₂O) semiconductor for good light harvesting, hole-transport layers (HTL: FeOOH) that mediate and stipulate interfacial charge transfer derection from Cu₂O to FTO, and a polypyrrole (PPy) layer as a sequential multi-electron transfer agent for CO₂ reduction. The integrated Cu₂O photocathode exhibits a record CO yield of up to 46.17 μmol h⁻¹ at −2.0 V vs. Ag/Ag⁺, which achieves a high half-cell solar to CO efficiency (η_STC) of 1.58% and delivers an optimal quantum efficiency of 3.08%, transcending most of the previous Cu₂O based photocathodes. Moreover, the integrated photocathode systems exhibit 7 hours operational stability. This work could shed light on designing and constructing efficient photocathode architecture for enabling practical solar-driven CO₂ reduction as a means of solar energy storage.