Design of bimetallic single-atom catalysts and theoretical study of CO2 reduction reaction

The electrocatalytic conversion of CO₂ represents a promising strategy toward achieving carbon neutrality, where single-atom catalysts (SACs) with atomically dispersed metal centers demonstrate exceptional potential for the CO₂ reduction reaction (CO₂RR). This work develops Co_xFe_3−x–O₄–C₄N SACs (x = 0–3) featuring tailored multi-metallic sites and systematically investigates their CO₂RR pathways and competitive hydrogen evolution reaction (HER) pathway through density functional theory (DFT) calculations. Detailed analysis of key intermediates reveals that the Fe sites in Co₁Fe₂–O₄–C₄N SACs exhibit optimal performance for HCOOH production, achieving a remarkably low energy barrier of 0.51 eV at the rate-determining step. Comparative studies demonstrate that Fe incorporation effectively suppresses competitive HER at Co sites while simultaneously modulating the electronic structures and charge transfer ability, which optimizes intermediate adsorption configurations, particularly enhancing activity and selectivity toward HCOOH generation. The findings establish a fundamental framework for designing multi-metallic SACs with precisely engineered active sites and high selectivity for special high-value-added chemicals.