Formic Acid Electro-synthesis by Concurrent Cathodic CO2 Reduction and Anodic CH3OH Oxidation.

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, which, however, suffers from the kinetic-sluggish anodic oxygen evolution reaction (OER) and its less value-added production of O 2 . Herein, we report a general strategy for efficient formic acid synthesis by 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 versus reversible hydrogen electrode (RHE) to obtain 100 mA cm -2 , featuring a significantly enhanced electro-activity in comparison to OER. Meanwhile, 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 . Moreover, 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.