Principles of coordination structure design of single‐atom catalysts in electrocatalytic oxygen reduction reaction

Abstract Proton exchange membrane fuel cells have been identified as a potentially valuable technology for the efficient conversion of hydrogen energy into electrical energy. Nevertheless, one significant constraint on the performance of fuel cells is the oxygen reduction reaction (ORR). It is meaningful to progress the development of representative ORR electrocatalysts. In recent times, there has been an intensified focus on single‐atom catalysts (SACs) due to the advantages of homogeneous distribution and high atom utilization efficiency. In particular, the coordination structure of metal sites plays an important role in the electrochemical performance of SACs. However, the relationship between coordination structures and catalytic performance remains unclear. In this review, we summarized the research progress on SACs in electrocatalytic ORR in recent years. Then the structure–activity relationship in the symmetric and asymmetric coordination structures of SACs was clarified. We further proposed rational design principles for regulating the coordination structure of SACs. Finally, the opportunities and challenges were discussed.