Gas phase electrocatalytic conversion of CO2 to syn-fuels on Cu based catalysts-electrodes

Abstract

A novel electrocatalytic system based on a low temperature proton exchange membrane (Sterion) was developed for the gas phase electrocatalytic conversion of CO2. This configuration allows the introduction of renewable energy in the chemical production chain via fuels production from direct CO2 electro-reduction at atmospheric pressure and low temperatures (below 90°C). For that purpose, three different Membrane Electrode Assemblies (MEAs) based on three different Cu based cathodic-catalysts were prepared and characterized: Cu-G/Sterion/IrO2, Cu-AC/Sterion/IrO2 and Cu-CNF/Sterion/IrO2; graphite (G), activated carbon (AC) and carbon nanofibers (CNF). Thus, H2O was fed and electrolyzed on the IrO2 anode of the cell, thereby supplying H+ across the membrane to react with CO2 in the cathodic-catalyst and leading to the production of a mixture of syn-fuels (syn-gas, methanol, methane…). Remarkably, the nature of the cathodic-catalyst carbon support had a strong influence on the electrocatalytic activity and selectivity of the system. Hence, the Cu-AC-based cathodic-catalyst showed the highest CO2 electrocatalytic activity, due to the highest surface area of the AC support and the larger metal dispersion of the Cu particles leading to acetaldehyde and methanol as the main reaction products. Besides the lower conductivity of the AC support, the lowest energy consumption values for CO2 conversion and methanol and acetaldehyde production was also achieved with the MEA based on Cu-AC cathodic catalyst due to its higher electrocatalytic activity.