Investigation of Electrocatalytic CO ₂ Reduction on MXene Materials via First-Principles Simulations

Computational studies of CO2 reduction to yield various products were carried out on the basal plane and edges of different MXene materials. The impact of vacancies upon Mo2TiC2Tx, W2TiC2Tx, and Ti3C2Tx (Tx = O and OH) was also examined for both edge and basal sites. Initial calibrations were carried out to generate surfaces with optimal oxide/hydroxide ratios and proper termination sites upon which various vacancy sites were explored to ensure an accurate model of the surfaces’ resting states. From this work, Mo2TiC2O was determined to exhibit the lowest theoretical overpotential for methane as determined by volcano plot analyses. At a large enough vacancy concentration, the CO2 reduction reaction (CO2RR) is predicted to outcompete the hydrogen evolution reaction (HER) as the predominant reaction on the surface. When examining the edge of Mo2TiC2O, stronger CO2 binding was exhibited to such an extent that the reaction was predicted to terminate after the generation of formate on the edge.