Intrinsic electronic structure modulation of M–N–C catalysts for selective oxygen reduction to hydrogen peroxide
摘要
The 4e−/2e− oxygen evolution reaction (ORR) pathway is crucial to determining the application direction in energy and environmental fields. Compared with the 4e− pathway that is thermodynamically favored, the high demand for 2e− pathway products (hydrogen peroxide) in daily life, healthcare, and chemical production urgently requires researchers to devote more effort to developing strategies to reverse the ORR pathway (from 4e− to 2e−) to enhance 2e− ORR selectivity. Therefore, it is imperative to clarify the selective mechanism of ORR and develop efficient and stable specific application catalysts. Inspired by this, in this review, the fundamental reaction mechanisms and factors determining selective trends are first outlined. Subsequently, focusing on the intrinsic electrocatalytic selectivity of M–N–C SACs, based on the coordination structure (metal center, first/second coordination shell and remote coordination environment), we summarized effective strategies that can selectively control the 2e− pathway of ORR. Theoretical predictions with experimental validation are both included to achieve a comprehensive understanding of the structure-selectivity relationship in metal centers. Finally, addressing the limitations of existing strategies for switching between two ORR reaction pathways, it outlines future research directions for developing more efficient, precise, and advanced M–N–C SACs.