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

Graphical A hollow victory : The mass transport and reaction process of the CO 2 reduction reaction on copper-tin alloy hollow fibers are investigated. The reason for suppressing hydrogen evolution reaction is revealed by comparing the influence of different gas injection ways. The high performance of formate production on Cu−Sn 45% alloy hollow fiber is attributed to the favorable crystal phase and the unique structure. 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 %.