Tuning CO2 electroreduction to methane via oxygen termination of M2BO2 (M = V, Cr, Hf, Mo, Ta, W) MBene catalysts: a DFT + U investigation.

Abstract

CO₂ is a principal greenhouse gas driving climate change, and converting it into useful fuels is a central goal of green chemistry and sustainable energy. Accordingly, we investigated M₂B and oxygen-terminated M₂BO₂ (M = V, Cr, Hf, Mo, Ta, W) monolayers for CO₂ electroreduction using DFT + U. Bare M₂B strongly chemisorbs and activates CO₂, but suffers from high overpotentials due to strong oxygen binding. Oxygen termination stabilizes the monolayers, moderates adsorption, and improves selectivity. Among the studied systems, W₂BO₂ and Hf₂BO show the most promising performance. W₂BO₂ exhibits a low limiting potential of -0.67 eV and an overpotential of 0.84 V, while Hf₂BO₂ achieves a limiting potential of -0.85 eV, thereby balancing CO₂ activation with efficient product desorption. These results demonstrate that oxyboride catalysts can convert CO₂ into methane while mitigating greenhouse gas emissions, offering a pathway toward sustainable fuel production and climate change solutions.