First-principles investigation of methane to methanol conversion on Ti2CO2 MXene supported single-atom catalyst

Abstract

Developing efficient catalysts for the conversion of methane (CH₄) to methanol (CH₃OH) remains a critical challenge in the chemical industry, with significant implications for both energy production and environmental sustainability. This study pioneers the exploration of the Sc/Ti-Ti₂CO₂ single-atom catalysts (SACs) for this transformation, utilizing density functional theory (DFT) calculations. Notably, our findings reveal that Sc and Ti are uniquely stable on the Ti₂CO₂ MXene surface, a discovery that could inform future catalyst designs. We also demonstrate that while CH₄ weakly physisorbs on the Sc/Ti-Ti₂CO₂ surface, N₂O molecules decompose directly into N₂ and highly reactive O* species, which bind with Sc/Ti to drive the catalytic process. The oxidation of CH₄ proceeds in two steps: CH₄ + O* → CH₃* + OH* with reaction barriers of 0.58 eV (Sc) and 1.38 eV (Ti), followed by CH₃* + OH* → CH₃OH with barriers of 1.5 eV (Sc) and 1.61 eV (Ti). Importantly, the low desorption energy of CH₃OH, especially on Sc (0.85 eV), highlights the exceptional catalytic potential of Sc/Ti₂CO₂ for the direct conversion of CH₄ to CH₃OH. These results not only underscore the feasibility of using MXene-based SACs for CH₄ oxidation but also provide a theoretical foundation for the development of highly efficient catalysts in this domain.