Electrochemical CO2 Reduction on a Copper Wire Electrode in Tetraethylammonium Perchlorate Methanol at Extremely Low Temperature

The electrochemical reduction of CO2 in tetraethylammonium perchlorate methanol electrolyte was investigated with a copper wire electrode at an extremely low temperature (-30 C). The main products from CO2 by the electrochemical reduction were methane, ethylene, carbon monoxide, and formic acid. Under the optimum experimental conditions, 28.1% faradaic efficiency methane, 7.2% ethylene, 67.8% carbon monoxide, and 23.2% formic acid were produced from CO2 by the electrochemical reduction. The maximum partial current densities for CO2 reduction and hydrocarbons were 4.5 and 1.6 mA cm-2 at 4.0 V vs SCE, respectively. At -30 C, the efficiency of hydrogen formation, being a competitive reaction against CO2 reduction, was suppressed to less than 10.1%.