High selectivity and abundant active sites in atomically dispersed TM2C12 monolayer for CO2 reduction

Developing highly efficient single-atom catalysts (SACs) for electrocatalytic carbon dioxide reduction reaction (CO2RR) is a promising approach to promoting carbon neutrality. However, challenges such as low activity, selectivity and high costs hinder industrial scaling, attributed to the lack of innate activity or insufficient transition metal (TM) active site density in current catalysts. Therefore, the focus of CO2RR research remains on developing SACs with intrinsic catalytic activity, high TM coverage and cost-effectiveness. This study presents the design of carbon-based materials with ultra-high TM coverage (TM2C12) (TM = Mo, Ru, Rh, W, Re, Os and Ir) as electrocatalyst SACs for CO2RR using density functional theory calculations. Among these materials, W2C12 (W represents tungsten) demonstrates superior selectivity and catalytic activity for CO2RR to carbon monoxide (CO) products with overpotentials of 0.45 V and a W coverage of up to 71.84 wt%. To further enhance its catalytic activity, non-metallic (NM) coordination modification (NM = B, N, O, P doping and C vacancy) was explored on W2C12. The results indicate that N-doped W2C12 (N-W2C12) can significantly improve selectivity and catalytic activity, achieving an extremely low overpotential of 0.34 V. This research offers valuable insights into designing SACs with high activity, selectivity and stability for CO2RR and other catalytic reactions. [Display omitted] •The M2C12 catalysts possesses ultra-high coverage of TM active sites (57.11–72.73 wt%).•W2C12 shows impressive intrinsic CO2RR activity, with a low overpotential of 0.45 V.•N doping optimizes positive charge density and overcomes selectivity and activity challenges.•N-W2C12 exhibits exceptional selectivity and activity with an overpotential of only 0.34 V.•Designing descriptors based on intrinsic characteristics for CO2RR.