Formic Acid Electro‐Synthesis by Concurrent Cathodic CO2 Reduction and Anodic CH3OH Oxidation

Abstract The electrochemical conversion of carbon dioxide into energy‐carrying compounds or value‐added chemicals is of great significance for diminishing the greenhouse effect and the efficient utilization of carbon‐dioxide emissions, but it suffers from the kinetically sluggish anodic oxygen evolution reaction (OER) and its less value‐added production of O 2 . We report a general strategy for efficient formic‐acid synthesis by a concurrent cathodic CO 2 reduction and anodic partial methanol‐oxidation reaction (MOR) using mesoporous SnO 2 grown on carbon cloth (mSnO 2 /CC) and CuO nanosheets grown on copper foam (CuONS/CF) as cathodic and anodic catalysts, respectively. Anodic CuONS/CF enables an extremely lowered potential of 1.47 V vs. RHE (100 mA cm −2 ), featuring a significantly enhanced electro‐activity in comparison to the OER. The cathodic mSnO 2 /CC shows a rather high Faraday efficiency of 81 % at 0.7 V vs. RHE for formic‐acid production from CO 2 . The established electrolyzer equipped with CuONS/CF at the anode and mSnO 2 /CC at the cathode requires a considerably low cell voltage of 0.93 V at 10 mA cm −2 for formic‐acid production at both sides.