Recent Advancements in Transition Metal-Nitrogen-Carbon Catalysts for Oxygen Reduction Reaction

Abstract

It remains a great challenge to replace platinum-based catalysts with earth-abundant materials to accelerate the sluggish oxygen reduction reaction (ORR) at the cathode, which is crucial for the future commercialization of fuel cells. Owing to the high catalytic activity, long-term durability and low cost, transition metal-nitrogen-carbon (M−N/C, M=Fe, Co, Ni, Mn, etc) materials have been widely recognized as the most promising non-precious metal catalysts (NPMCs) for ORR. In this review, the recent understanding of the ORR catalytic mechanism and the intrinsic nature of active sites is briefly introduced. Then, two crucial factors involved with careful selection of suitable M−N/C precursors and preferable control over the geometric structures of the catalysts are presented. Finally, we provide the insights into the remaining debates and challenges to illuminate the further development of ORR catalysts.