Ni Single Atoms/Fe₃N Nanoparticles Supported by N‐Doped Carbon Hollow Nanododecahedras with Nanotubes on the Surface for Efficient Electro‐Reduction of CO₂ to CO

The transition metal single atoms (SAs)-based catalysts with M-NX coordination environment have shown excellent performance in electrocatalytic reduction of CO₂, and they have received extensive attention in recent years. However, the presence of SAs makes it very difficult to efficiently improve the coordination environment. In this paper, a method of direct high-temperature pyrolysis carbonization of ZIF-8 adsorbed with Ni²⁺ and Fe²⁺ ions is reported for the synthesis of Ni SAs and Fe₃N nanoparticles (NPs) supported by the N-doped carbon (NC) hollow nanododecahedras (HNDs) with nanotubes (NTs) on the surface (Ni SAs/Fe₃N NPs@NC-HNDs-NTs). The synergistic effect between Ni SAs and Fe₃N NPs can obviously improve the proton-coupled electron transfer step of CO₂ reduction reaction and promotes the process of electrocatalytic reduction of CO₂ to CO. The fabricated Ni SAs/Fe₃N NPs@NC-HNDs-NTs exhibits a high CO selectivity of up to 94% in the potential range of -0.41--0.81 V versus Reversible Hydrogen Electrode (vs RHE), and an optimal CO Faraday efficiency (FECO) of ≈97.31% at -0.68 V (vs RHE) in the reduction reaction CO₂ to CO. In the theoretical calculation results, due to the non-bonding synergy effect between Ni SAs and Fe₃N NPs, the free energy of *COOH formation is greatly reduced and the adsorption of *CO is obviously improved, which will efficiently promote the conversion between the intermediates in the reaction step and accelerate electro-reduction process of CO₂. This work will provide a new method for constructing a mutually optimized coordination environment between Ni SAs and Fe₃N NPs to improve the catalytic performance of CO₂RR by synergistic complementarity between the dual active sites.