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

Abstract

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 (U_L) 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.