Electrochemical CO2 reduction to methanol over Ni@Ti3CN MXene: a first-principles DFT study.

Electrochemical carbon dioxide (CO2) reduction is a promising solution for the conversion of CO2 to CH3OH. In this study, we investigated the catalytic activity of nickel-decorated Ti3CN (Ni@Ti3CN) using density functional theory combined with a computational hydrogen electrode (CHE) model. This study was completely carried out using an implicit solvation model to understand the impact of the solvent on the production of CH3OH via electrochemical CO2 reduction. Using ab initio molecular dynamics (AIMD), Ni@Ti3CN was found to be thermally stable at T = 300 K. The catalyst activated CO2 in the side-on orientation, where visible changes in its bond length and angle were observed with an adsorption energy of -0.12 eV. The rate-determining step (RDS) in the overall reaction is the formation of *CO (RDS) with a corresponding free energy change (ΔG) of 0.59 eV. This intermediate plays a crucial role in the CO2 reduction reaction (CO2RR). The calculated limiting potential (UL) for the reaction is -0.59 V, corresponding to a low overpotential of 0.61 V. The faradaic efficiency for CH3OH production is approximately 99.9%. These results demonstrate that Ni@Ti3CN is a promising candidate for electrochemical CO2 reduction, highlighting the potential of carbonitride-based MXenes for future CO2 reduction applications.