Insights into the activity of single-atom Fe-N-C catalysts for oxygen reduction reaction

• Published in: Nature communications Vol. 13; no. 1; pp. 2075 - 8
• Main Authors: Liu, Kang, Fu, Junwei, Lin, Yiyang, Luo, Tao, Ni, Ganghai, Li, Hongmei, Lin, Zhang, Liu, Min
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 19.04.2022; Nature Publishing Group; Nature Portfolio
• Subjects: 119/118; 639/638/161/886; 639/638/440/94; 639/638/563/606; Adsorption; Carbon; Catalysts; Catalytic activity; Chemical reduction; Density functional theory; Divacancies; Energy; Energy levels; Humanities and Social Sciences; Hybridization; Magnetic moments; multidisciplinary; Orbitals; Oxygen; Oxygen reduction reactions; Science; Science (multidisciplinary)
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-022-29797-1

Single-atom Fe-N-C catalysts has attracted widespread attentions in the oxygen reduction reaction (ORR). However, the origin of ORR activity on Fe-N-C catalysts is still unclear, which hinder the further improvement of Fe-N-C catalysts. Herein, we provide a model to understand the ORR activity of Fe-N 4 site from the spatial structure and energy level of the frontier orbitals by density functional theory calculations. Taking the regulation of divacancy defects on Fe-N 4 site ORR activity as examples, we demonstrate that the hybridization between Fe 3 dz 2 , 3 dyz (3 dxz ) and O 2 π* orbitals is the origin of Fe-N 4 ORR activity. We found that the Fe–O bond length, the d-band center gap of spin states, the magnetic moment of Fe site and *O 2 as descriptors can accurately predict the ORR activity of Fe-N 4 site. Furthermore, these descriptors and ORR activity of Fe-N 4 site are mainly distributed in two regions with obvious difference, which greatly relate to the height of Fe 3 d projected orbital in the Z direction. This work provides a new insight into the ORR activity of single-atom M-N-C catalysts. It is of high importance to understand the origin of single-atom Fe-N 4 activity in oxygen reduction reaction. Here, the authors provide a model to understand the catalytic activity of Fe-N 4 site from the spatial structure and energy level of the frontier orbitals by density functional theory calculations.