Formate‐Selective CO2 Electrochemical Reduction with a Hydrogen‐Reduction‐Suppressing Bronze Alloy Hollow‐Fiber Electrode

Abstract Electroreduction carbon dioxide into formate has been regarded as a hopeful measure to relieve global warming. Copper‐based hollow fibers demonstrated good performances on converting carbon dioxide in previous researches. Herein Cu−Sn alloy hollow fibers were synthesized in an innovative way, combining the structure advantages of hollow fiber and high selectivity towards formate on η′ bronze. Tests under different gas injection conditions were conducted to analyze the contribution of the hollow fiber structure on suppression of hydrogen evolution and promotion on kinetics. Strikingly, Cu−Sn 45 % hollow fiber, the optimal catalyst in this work, achieved a highest faradaic efficiency towards formate of 90.96 % at a lower potential of −0.75 V vs. RHE than most non‐noble catalysts, and the FE of H 2 was below 4 %.