Remote p-d orbital hybridization first/second-layer coordination of Fe single atoms with heteroatoms for enhanced electrochemical CO-to-CO reduction

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2024-04, Vol.12 (15), p.8991-91
• Main Authors: Yang, Ying, Chen, Lizhen, Guo, Zhenyan, Liu, Shengqi, Wu, Pei-dong, Fang, Zhen, Zhang, Kai, Li, Hu
• Format: Article
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/d3ta08021h

The electrochemical CO 2 reduction reaction (CO 2 RR) to CO is closely correlated with appropriate sorption of *COOH and *CO species toward the electrode surface, and the proton transfer process that often competes with the hydrogen evolution reaction (HER). Herein, an unconventional p-d orbital hybridization induced by doping of S to the second coordination layer of atomically dispersed pyrrole-type Fe-N 4 (S/Fe-poN 4 -C) could not only modulate the binding strength between *COOH and pyrrole-type Fe single atoms but also facilitate the succedent desorption of *CO, effectively hindering the occurrence of the HER. An excellent CO 2 RR performance was achieved in an H-type cell over S/Fe-poN 4 -C, with CO Faraday efficiency of 98.2% and turnover frequency of 4621.2 h −1 , superior to the S-free pyridine-type Fe-N 4 catalyst and previously reported electrodes. In situ characterization techniques and theoretical calculations demonstrated that the constructed p-d orbital hybridization suitably balanced the adsorption of the *COOH intermediate by accelerating proton transfer and further desorption of *CO by optimizing the nitrogen coordination environment of the electrocatalyst, which could also stabilize the atomic Fe sites to avoid aggregation. The remote p-d orbital hybridization strategy offers an alternative approach for more precious regulation of both the electronic and coordination structure of the electrodes for highly selective CO 2 RR. d-p orbital hybridization induced by S/N in the coordination layer of pyrrole-type Fe-N 4 can modulate the electronic structure of Fe single atoms, enabling *COOH adsorption and *CO desorption to exclusively furnish CO but suppressing H 2 formation.