Highly Selective CO2 Electroreduction to C1 Products on Two-Dimensional BC4N Supported Single Transition Metal Catalysts: A DFT Study

Abstract

Motivated by carbon peak and neutrality targets of China, the electrochemical conversion of CO2 emitted from coal-fired power plants into C1 fuels using surplus renewable electricity presents a promising strategy for carbon mitigation and energy storage. Here, we systematically screened 25 single transition-metal (TM) atoms anchored on a two-dimensional BC4N substrate (TM@BC4N) for the CO2 reduction reaction (CO2RR) via density functional theory (DFT). Based on binding energies and hydrogen evolution reaction competition, 12 thermodynamically stable systems were identified. Ab initio molecular dynamics confirmed the structural robustness of Co@BC4N. Gibbs free energy calculations reveal a fascinating divergence in selectivity: Zn@BC4N exhibits the highest selectivity toward two-electron formic acid (HCOOH) with a rate-determining step, free energy change of only 0.24 eV, while Co@BC4N shows superior catalytic activity toward eight-electron methane (CH4) with an ultralow rate-determining step, free energy change of 0.14 eV. Mechanistic insights from Bader charge, d-orbitals center, and integrated crystal orbital Hamilton population analyses unveil that the moderate charge transfer and optimal d-orbitals center in Co@BC4N balance intermediate adsorption and C–O bond activation, whereas configuration of Zn restricts further hydrogenation. This work not only identifies Co@BC4N as a promising CH4 catalyst but also provides a theoretical framework for designing selective CO2RR catalysts.