The combined effect of temperature and pressure on the electrochemical CO2 reduction on Cu

Abstract

Research into the electrochemical CO2 reduction (CO2RR) is often performed at ambient conditions. However, these are probably not the most industrial relevant conditions, eventually leading to insufficient insights. Using a high-pressure high-temperature electrochemical cell, we have investigated the combined effect of temperature and pressure on the CO2RR on Cu. We show that temperature has a larger effect on the selectivity than pressure and increasing temperature up to 75 degrees C can increase the C2+ formation. However, stability becomes a bigger issue at higher temperatures, while higher pressures increase the stability as evidenced by the time dependence of the ethylene selectivity. Moreover, elevated pressures can suppress the competing hydrogen evolution reaction and increase both activity and selectivity of CO2RR significantly, even at a few bars of pressure, as long as these pressures are CO2 pressures and not reached by an inert gas.