Transition metal-loaded C2N catalysts for selective CO2 reduction to CH4: Insights from first-principles calculations

The escalating atmospheric CO2 levels due to fossil fuel consumption pose significant environmental challenges, including the greenhouse effect and ocean acidification. Converting CO2 into valuable fuels and chemicals through electrochemical CO2RR is a promising strategy to mitigate these issues. However, the high thermodynamic stability of CO2 and the competing HER present challenges in achieving high selectivity and efficiency. This study employs first-principles calculations to investigate the performance of transition metal trimer catalysts (3TM-C2N, TM = Mn, Mo, Ru, Ti) supported on porous graphitic C2N for CO2RR to CH4. The catalysts were constructed and their stability, electronic structure, and CO2 adsorption mechanisms were systematically analyzed using DFT. The results indicate that 3TM-C2N catalysts are structurally stable, efficiently adsorb and activate CO2, and effectively suppress HER. Notably, 3Mn-C2N demonstrated optimal selectivity for CH3OH and CH4 with a limiting potential of -0.44 V, while 3Ru-C2N showed superior selectivity for the same products at limiting potentials of -0.86 V and -0.73 V, respectively. These findings provide theoretical insights for the experimental optimization of C2N-based catalysts and guide the development of efficient CO2RR electrocatalysts.