Trends of Electrochemical CO2 Reduction Reaction on Transition Metal Oxide Catalysts

Density functional theory calculations were used to explore reactivity trends of the electrochemical CO2 reduction reaction (CO2RR) toward methanol, methane, methanediol, and formic acid on 12 transition metal dioxide (TMO) surfaces in their rutile structure. The (110) facet of the TMOs was used as a model system to investigate the thermodynamic limiting potentials of CO2RR. Activity and selectivity volcano plots for various products were obtained through the scaling relations of adsorbed intermediates. RhO2 is predicted to be a good catalyst for production of formic acid with low onset potential of around -0.2 V. In addition to its high activity, hydrogen evolution reaction (HER) is predicted to not limit its efficiency due to weak hydrogen binding free energy on this oxide. CrO2 is another promising candidate for CO2RR with onset potential of around -0.3 V toward most of the products. CrO2 seems to be more interesting than RhO2 for production of methanol, methane, and methanediol as it adsorbs HCOOH on its surface in a dissociated form. CrO2 is also predicted to be more selective toward these CO2RR products than toward forming hydrogen gas.