High throughput screening of M3C2 MXenes for efficient CO2 reduction conversion into hydrocarbon fuels

Abstract

The electrocatalytic reduction conversion of CO₂ to produce methane (CH₄) as a fuel has attracted intensive attention for renewable energy. Density functional theory (DFT) calculations with a computational hydrogen electrode (CHE) model are applied to study the hydrogenation of CO₂ on the two-dimensional (2D) M₃C₂ transition metal carbide (MXenes) surface. It is demonstrated that the adsorbed CO₂ is activated and can combine with surface hydrogen to form bicarbonate species, thus leading to more competitive selectivity for the CO₂RR than the HER. All possible conversion pathways for carbon dioxide to methane are explored, and it is found that the formation of the bicarbonate (HCO₂) species is energetically the most favourable reaction pathway, whereas the main intermediate of the CO₂RR is HCHO. Detailed characterization of the initial activation, scaling relationships, protonation steps and electrode overpotential, together with the evaluation of the limiting potentials for several reaction mechanisms, reveals that MXene M₃C₂ exhibits a high catalytic performance for CO₂, providing novel fuel cells.