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.