Efficient X₂TiC₂ (X = V, Cr, Nb, Mo) MXenes Catalysts for Electrochemical CO₂ Reduction: First-Principles Study

Based on ab initio molecular dynamics (AIMD) simulations and density functional theory (DFT), this study deeply evaluated the stability and catalytic performance of different catalysts X 2 TiC 2 (X = V, Cr, Nb, Mo) MXenes in the carbon dioxide reduction reaction (CO 2 RR). Through density of states (PDOS) analysis, the adsorption characteristics of CO 2 on the X 2 TiC 2 surface and its reaction mechanism were systematically revealed. Combined with the Gibbs free energy(Δ G ), the three main reaction pathways of CO 2 RR, namely the two-electron and six-electron pathways and the eight-electron pathway, were discussed in detail. The study shows that all X 2 TiC 2 catalysts exhibit high desorption energies during CO generation, which helps to improve the selectivity of the multi-electron reaction products while highlighting the key role of reducing CO desorption energy in improving catalytic efficiency. Among various X 2 TiC 2 materials, Nb 2 TiC 2 exhibits excellent catalytic performance in generating CH 3 OH via a six-electron pathway, with a required Δ G of only 0.69 eV, showing good generation efficiency. At the same time, Mo 2 TiC 2 also exhibits superior catalytic activity in generating CH 4 via an eight-electron pathway, with a limiting step Δ G of 0.67 eV. In summary, this study reveals the excellent catalytic performance of Nb 2 TiC 2 and Mo 2 TiC 2 , showing their great potential in practical applications. This discovery provides new ideas for designing and optimizing MXene material catalysts, and has important academic value and application prospects.