Screening of Transition Metal Supported on Black Phosphorus as Electrocatalysts for CO₂ Reduction

The electrocatalytic CO₂ reduction (CO₂RR) is an effective and economical strategy to eliminate CO₂ through conversion into value-added chemicals and fuels. However, exploring and screening suitable 2D material-based single-atom catalysts (SACs) for CO₂ reduction are still a great challenge. In this study, 27 (3d, 4d, and 5d, except Tc and Hg) transition metal (TM) atom-doped black phosphorus (TM@BP) electrocatalysts were systematically investigated for CO₂RR by density functional theory calculations. According to the stability of SACs and their effectiveness in activating the CO₂ molecule, three promising catalysts, Zr@BP, Nb@BP, and Ru@BP, were successfully screened out, exhibiting outstanding catalytic activity for the production of carbon monoxide (CO), methyl alcohol (CH₃OH), and methane (CH₄) with limiting potentials of -0.79, -0.49, and -0.60 V, respectively. A catalytic relationship between the d-band centers of SACs and the limiting potential of CO₂RR was used to estimate the catalytic activity of catalysts. Furthermore, Nb@BP has high selectivity for CO₂RR to CH₃OH compared to H₂ formation, while the hydrogen evolution reaction significantly impacts the synthesis of CO and CH₄ on Zr@BP and Ru@BP. Nitrogen atom doping in BP is beneficial for enhancing the selectivity of CO₂RR, but it is detrimental to the activity of CO₂RR. This study offers theoretical guidance for synthesizing highly efficient CO₂RR electrocatalysts and further enhances structural modulation methods for layered 2D materials.