Unveiling the In Situ Generation of a Monovalent Fe(I) Site in the Single-Fe-Atom Catalyst for Electrochemical CO2 Reduction

作者：Xuning Li, Yaqiong Zeng, Ching-Wei Tung, Ying‐Rui Lu, Sambath Baskaran, Sung‐Fu Hung, Shifu Wang, Cong‐Qiao Xu, Junhu Wang, Ting‐Shan Chan, Hao Ming Chen, Jianchao Jiang, Qi Yuan Yu, Yanqiang Huang, Jun Li, Tao Zhang, Bin Liu · 发表于：ACS Catalysis · 年份：2021 · DOI：10.1021/acscatal.1c01621 · 被引用次数：95 · 研究领域：CO2 Reduction Techniques and Catalysts、Electrocatalysts for Energy Conversion、Catalytic Processes in Materials Science

Atomically dispersed single-atom catalysts are among the most attractive electrocatalysts for the CO 2 reduction reaction (CRR). To elucidate the origin of the exceptional activity of atomically dispersed Fe–N–C catalyst in CRR, we have performed operando 57 Fe Mössbauer spectroscopic studies on a model single-Fe-atom catalyst with a well-defined N coordination environment. Combining with operando X-ray absorption spectroscopy, the in situ-generated four pyrrolic nitrogen atom-coordinated low-spin Fe(I) (LS Fe I N 4 ) featuring monovalent iron is identified as the reactive center for the conversion of CO 2 to CO. Furthermore, density functional theory calculations reveal that the optimal binding strength of CO 2 to the LS Fe I N 4 site, with strong orbital interactions between the singly occupied d z 2 orbital of the Fe(I) site and the singly occupied π* orbital of [COOH] fragment, is the key factor for the excellent CRR performance.