Electrolyte Driven Highly Selective CO₂ Electroreduction at Low Overpotentials

Electrochemical CO2 reduction reaction (CO2RR) is a promising technology to use renewable electricity to convert CO2 into value-added carbon-based products. The low-cost, active, selective, and stable catalysts will play a key role in achieving industrialized CO2RR. The electrolyte assists a catalyst in achieving all its latent capability. Here the concentration effect of KHCO3 in CO2RR was systematically investigated on the low-cost core–shell structured Cu2O@SnOx nanoparticle-derived hybrid catalyst. An HCO3–-involved proton-coupled electron transfer was confirmed as the rate-determining step for CO2RR on the hybrid catalyst in aqueous KHCO3 solution based on the analysis of the reaction order and Tafel slope. The nearly 100% selectivity for CO was achieved in a highly concentrated KHCO3 solution accompanied by a high cathodic energetic efficiency of 71.8%. It was attributed to the combined concentration effect of KHCO3 with the related pH effect.