Photovoltaic-Powered Electrochemical CO₂ Reduction: Benchmarking against the Theoretical Limit

In this work, benchmarking against the theoretical limit and against water splitting was used to indicate the promise of photovoltaic-powered electrochemical CO₂ reduction. A benchmark device was built by the successful integration of high-performance cathode, anode, membrane-electrode-assembly reactor and dual-junction photoabsorber. This is the first report on dual-junction photoabsorber-driven CO₂ electrolysis. We experimentally demonstrated a record-high solar-to-chemical energy conversion efficiency of 21.3% and a projected efficiency of 25.3%. This performance metric remarkably reaches 87% of the theoretical efficiency limit and surpasses the solar-to-hydrogen efficiency based on the same photoabsorber. This work paves the way for efficient solar fuel production with solar CO as the intermediate.