Regulating Spin Polarization via Axial Nitrogen Traction at Fe−N<sub>5</sub> Sites Enhanced Electrocatalytic CO<sub>2</sub> Reduction for Zn−CO<sub>2</sub> Batteries
Yanran Bao, Jiayong Xiao, Yongkang Huang, Youzhi Li, Siyu Yao, Ming Qiu, Xiaoxuan Yang, Lecheng Lei, Zhongjian Li, Yang Hou, Gang Wu, Bin Yang
Abstract
Abstract Single Fe sites have been explored as promising catalysts for the CO 2 reduction reaction to value‐added CO. Herein, we introduce a novel molten salt synthesis strategy for developing axial nitrogen‐coordinated Fe‐N 5 sites on ultrathin defect‐rich carbon nanosheets, aiming to modulate the reaction pathway precisely. This distinctive architecture weakens the spin polarization at the Fe sites, promoting a dynamic equilibrium of activated intermediates and facilitating the balance between *COOH formation and *CO desorption at the active Fe site. Notably, the synthesized FeN 5 , supported on defect‐rich in nitrogen‐doped carbon (FeN 5 @DNC), exhibits superior performance in CO 2 RR, achieving a Faraday efficiency of 99 % for CO production (−0.4 V vs. RHE) in an H‐cell, and maintaining a Faraday efficiency of 98 % at a current density of 270 mA cm −2 (−1.0 V vs. RHE) in the flow cell. Furthermore, the FeN 5 @DNC catalyst is assembled as a reversible Zn−CO 2 battery with a cycle durability of 24 hours. In situ IR spectroscopy and density functional theory (DFT) calculations reveal that the axial N coordination traction induces a transformation in the crystal field and local symmetry, therefore weakening the spin polarization of the central Fe atom and lowering the energy barrier for *CO desorption.