Electrochemical conversion of carbon dioxide to formic acid on Pb in KOH/methanol electrolyte at ambient temperature and pressure

The electrochemical reduction of CO2 in KOH/methanol-based electrolyte has been investigated on a lead wire electrode at ambient temperature and pressure. The major products of electrochemical reduction of CO2 were formic acid, CO and methane. The formation of formic acid from CO2 predominated in the potential range −1.8 to −2.5 V vs Ag/AgCl (saturated KCl). Hydrogen evolution in competition with CO2 reduction was observed at only 3.5% faradaic efficiency. The partial current density for CO2 reduction was more than 22 times larger than that for hydrogen evolution. Study of the Tafel plot showed that the reduction of CO2 to formic acid and CO was not limited by mass transfer in this potential range.