A high-performance oxygen evolution catalyst in neutral-pH for sunlight-driven CO2 reduction

Abstract

The efficiency of sunlight-driven reduction of carbon dioxide (CO₂), a process mimicking the photosynthesis in nature that integrates the light harvester and electrolysis cell to convert CO₂ into valuable chemicals, is greatly limited by the sluggish kinetics of oxygen evolution in pH-neutral conditions. Current non-noble metal oxide catalysts developed to drive oxygen evolution in alkaline solution have poor performance in neutral solutions. Here we report a highly active and stable oxygen evolution catalyst in neutral pH, Brownmillerite Sr₂GaCoO₅, with the specific activity about one order of magnitude higher than that of widely used iridium oxide catalyst. Using Sr₂GaCoO₅ to catalyze oxygen evolution, the integrated CO₂ reduction achieves the average solar-to-CO efficiency of 13.9% with no appreciable performance degradation in 19 h of operation. Our results not only set a record for the efficiency in sunlight-driven CO₂ reduction, but open new opportunities towards the realization of practical CO₂ reduction systems.