Large Current Density CO2 Reduction under High Pressure Using Gas Diffusion Electrodes

Abstract Electrochemical reduction of CO2 was studied under high pressure on Co, Rh, Ni, Pd, Pt, Ag, and Cu electrocatalysts supported in the gas diffusion electrode (GDE). CO was produced on Pd and Ag catalysts at faradaic efficiencies of 58 and 86%, respectively, at 300 mA cm−2 under CO2 20 atm. In the case of Cu-GDE, CO and formic acid were produced as the main reduction products. Hydrogen was the predominant reduction product in the electrolyses using other GDEs. Effects of the CO2 pressure, the current density, and the passed charge in the electrochemical reduction of CO2 using Pd and Ag-GDEs were investigated in detail. The maximum partial current density of CO formed on the Pd-GDE under CO220 atm was 450 mA cm−2. A very large partial current density of CO formation of 3.05 A cm−2 was achieved in the electrolysis under 30 atm on the Ag-GDE.