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

[Display omitted] •The innovative design of triatomic transition metal catalysts (3TM-C2N) on porous graphitic C2N offers a promising approach to enhance CO2 reduction reactions.•The application of first-principles calculations, particularly DFT, represents an innovative method for analyzing the structural stability and electronic properties of newly designed catalysts.•The use of d-band center theory and differential charge density analysis provides innovative insights into the initial activation and adsorption mechanisms of CO2 on catalyst surfaces.•The identification of optimal pathways and limiting potentials for selective CO2 reduction to CH3OH and CH4, especially for 3Mn-C2N and 3Ru-C2N, marks an innovative contribution to the field of electrocatalyst development. 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.