Calculations of Product Selectivity in Electrochemical\nCO₂ Reduction

Abstract

CO₂ can be reduced electrochemically to form valuable\nchemicals such as hydrocarbons and alcohols using copper electrodes,\nwhereas the other metal electrodes tested so far mainly form CO or\nformate, or only the side product, H₂. Accurate modeling\nof electrochemical reaction rates including the complex environment\nof an electrical double layer in the presence of an applied electrical\npotential is challenging. We show here that calculated rates, obtained\nusing a combination of density functional and rate theory, are in\nclose agreement with available experimental data on the formation\nof the various products on several metal electrodes and over a range\nin applied potential, thus demonstrating the applicability of the\ntheoretical methodology. The results explain why copper electrodes\ngive a significant yield of hydrocarbons and alcohols, and why methane,\nethylene, and ethanol are formed in electroreduction rather than methanol,\nwhich is the main product when H₂ gas reacts with CO₂ on copper catalyst. The insight obtained from the calculations\nis used to develop criteria for identifying new and improved catalysts\nfor electrochemical CO₂ reduction.