Carbon-based catalysts of the oxygen reduction reaction: Mechanistic understanding and porous structures

Carbon-based catalysts are potential substitutes for noble-metal catalysts in the oxygen reduction reaction (ORR) owing to their excellent electrical conductivities and chemical stabilities. To rationally design and accelerate the identification of highly efficient carbon-based ORR catalysts, improving the design of the active sites and microstructures is necessary. In this review, strategies for improving the intrinsic performances, activities, stabilities, and anti-poisoning properties of catalysts are analyzed. As a critical component of the microstructure, the porous structures of catalysts significantly affect their distributions of active sites and levels of mass transfer, which are also extensively analyzed. Finally, based on the formation of active sites and the fabrication of porous structures, conclusions and perspectives regarding the future development of highly efficient carbon-based electrocatalysts are provided.