Co-Electrolysis of CO2 and H2O: from Electrode Reactions to Cell Level Development

Abstract The electroreduction of CO2 into added-value products (e.g., CO) constitutes an excellent means of decreasing this greenhouse gas’ emissions, but limited efforts have been devoted to the implementation of this reaction within so-called co-electrolysis cells operating at process-relevant currents >> 100 mA·cmgeom−2. Reaching such performances shall require a combination of gas-fed reactants and corresponding diffusion electrodes, along with ion exchange membranes and ionomers that set the operative pH at the cells’ cathode and anode. The latter constitutes a key design parameter that must be combined with the need to minimize the crossover of reaction products and/or (bi)carbonate anions from cathode to anode, whereby their re-oxidation to carbon dioxide leads to a decrease of the device’s net CO2 consumption.