Computational screening of defective BC₃-supported single-atom catalysts for electrochemical CO₂ reduction

The electrochemical CO₂ reduction reaction (eCO₂RR) driven by renewable electricity offers a green and sustainable technology for synthesizing chemicals and managing global carbon balance. However, developing electrocatalysts with high activity and selectivity for producing C₁ products (CO, HCOOH, CH₃OH, and CH₄) remains a daunting task. In this study, we conducted comprehensive first-principles calculations to investigate the eCO₂RR mechanism using B-defective BC₃-supported transition metal single-atom catalysts (TM@BC₃ SACs). Initially, we evaluated the thermodynamic and electrochemical stability of the designed 26 TM@BC₃ SACs by calculating the binding energy and dissolution potential of the anchored TM atoms. Subsequently, the selectivity of the eCO₂RR and hydrogen evolution reaction (HER) on stable SACs was determined by comparing the free energy change (ΔG) for the first protonation of CO₂ with the ΔG of *H formation. The stability and selectivity screening processes enabled us to narrow down the pool of SACs to the 14 promising ones. Finally, volcano plots for the eCO₂RR towards different C₁ products were established by using the adsorption energy descriptors of key intermediates, and three SACs were predicted to exhibit high activity and selectivity. The limiting potentials (U_L) for HCOOH production on Pd@BC₃ and Ag@BC₃ are -0.11 V and -0.14 V. CH₄ is a preferred product on Re@BC₃ with U_L of -0.22 V. Elaborate electronic structure calculations elucidate that the activity and selectivity originate from the sufficient activation of the C-O bond and the strong orbital hybridization between crucial intermediates and metal atoms. The proposed catalyst screening criteria, constructed volcano plots and predicted SACs may provide a theoretical foundation for the development of computationally guided catalyst designs for electrochemical CO₂ conversion to C₁ products.