Selective oxygen reduction reaction pathway for carbon-based catalysts

Abstract

The oxygen reduction reaction (ORR) is crucial for cutting-edge energy conversion and storage systems. The selectivity of reaction pathways greatly impacts catalytic performance and determines the use of catalysts in these technologies. In this review, we summarize the research advancements on the selectivity of reaction pathways based on theoretical principles, clarifying the fundamental mechanisms of the 4e⁻ and 2e⁻ pathways, and elaborating their potential applications across various fields—bridging the existing gap of inadequate systematic connections between theoretical principles and practical applications. Subsequently, the design strategies for optimizing carbon-based electrocatalysts by tuning the central metal, coordination environment, and reaction microenvironment are discussed, along with the influence of different tuning methods. Meanwhile, the levering effect of heteroatom doping on the reaction pathways in metal-free carbon-based catalysts is also described, following which the environmental factors in the selectivity is emphasized. Finally, this review represents the challenges of existing research for ORR, and proposes future research directions, including establishing more accurate structure performance relationship models, exploring the potential of new coordination environments, and studying the influence of reaction kinetics on the ORR pathway selection. This work provides useful insights into advanced carbon-based electrocatalysis with designated ORR pathway.