Regulating Spin Polarization via Axial Nitrogen Traction at Fe−N5 Sites Enhanced Electrocatalytic CO2 Reduction for Zn−CO2 Batteries

• Published in: Angewandte Chemie International Edition 2024-10, Vol.63 (43), p.e202406030-n/a
• Main Authors: Bao, Yanran, Xiao, Jiayong, Huang, Yongkang, Li, Youzhi, Yao, Siyu, Qiu, Ming, Yang, Xiaoxuan, Lei, Lecheng, Li, Zhongjian, Hou, Yang, Wu, Gang, Yang, Bin
• Format: Article
• Language: English
• Subjects: Activated carbon; Axial N traction strategy; Battery cycles; Carbon dioxide; Catalysts; Chemical reduction; Chemical synthesis; CO2 electroreduction; Crystal defects; Density functional theory; Desorption; Infrared spectroscopy; Intermediates; Molten salt process; Molten salts; Nitrogen; Polarization; Polarization (spin alignment); Spin dynamics; Spin polarization; Traction; Zinc; Zn−CO2 battery
• ISSN: 1433-7851; 1521-3773; 1521-3773
• DOI: 10.1002/anie.202406030

Single Fe sites have been explored as promising catalysts for the CO2 reduction reaction to value‐added CO. Herein, we introduce a novel molten salt synthesis strategy for developing axial nitrogen‐coordinated Fe‐N5 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 FeN5, supported on defect‐rich in nitrogen‐doped carbon (FeN5@DNC), exhibits superior performance in CO2RR, 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 FeN5@DNC catalyst is assembled as a reversible Zn−CO2 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. Through the innovative design of a molten salt method, an axial N traction strategy is developed to reduce the spin polarization of the central Fe atom and achieve precise regulation of the atom. The prepared FeN5@DNC material can regulate the formation of *COOH and desorption of *CO in the electrocatalytic reduction of CO2, achieving ultra‐high selectivity and high current density of 99 %, and running stably in both flow cell and Zn−CO2 battery with good performance. It provides a new way to realize the precise regulation of M‐NC catalyst materials.