Synergistic Fe-Ni diatomic catalysts on 3D N-doped carbon for high-efficiency and stable electrochemical CO2 reduction to CO

Single-atom catalysts (SACs) have attracted attention in the research of CO₂RR due to their distinct atomic structure and performance features. However, their inherent shortcomings, such as limited stability and low charge transfer efficiency, also limit their further progress. In this study, a novel Fe-Ni diatomic catalyst (Fe₂/Ni₁-N-C) anchored on a three-dimensional nitrogen-doped carbon framework was successfully synthesized, demonstrating remarkable electrochemical activity and selectivity for converting CO₂ to CO. The Fe₂/Ni₁-N-C catalyst achieved a high Faraday efficiency (FE_CO) of 96 % when operated at -0.76 V (vs. RHE) and it maintained stable performance over 20 h of continuous operation. The experimental results show that maintaining the stability of the coordination environment at the atomic level of the catalyst plays an important role in its activity, selectivity and stability. Density functional theory (DFT) calculations supported the successful construction of adjacent Fe-Ni active sites, with atomic dispersion of NiN₄ and FeN₄. The synergistic effect between the bimetals was found to play a critical role in promoting the formation of *COOH intermediates and facilitating the desorption of *CO, thereby enhancing both CO selectivity and catalytic activity. This study provides valuable insights into the design of efficient diatomic catalysts for CO₂ electroreduction.