Abstract
Fe-N-C material, known for its high efficiency, cost-effectiveness, and environmental friendliness, is a promising electrocatalyst in the field of the oxygen reduction reaction (ORR). However, the influence of defects and coordination structures on the catalytic performance of Fe-N-C has not been completely elucidated. In our present investigation, based on density functional theory, we take an Fe adsorbed graphene structure containing a 5-8-5 divacancy (585DV) defect as a research model and investigate the influence of the coordination number of N atoms around Fe (Fe-N(x)C((4-x))) on the ORR electrocatalyst behavior in alkaline conditions. We find that the Fe-N(4) structure exhibits superior ORR catalytic performance than other N coordination structures Fe-N(x)C(4-x) (x = 0-3). We explore the reasons for the improved catalytic performance through electronic structure analysis and find that as the N coordination number in the Fe-N(x)C((4-x)) structure increases, the magnetic moment of the Fe single atom decreases. This reduction is conducive to the ORR catalytic performance, indicating that a lower magnetic moment is more favorable for the catalytic process of the ORR within the Fe-N(x)C((4-x)) structure. This study is of great significance for a deeper understanding of the structure-performance relationship in catalysis, as well as for the development of efficient ORR catalysts.