Heteroatom- and metalloid-doped carbon catalysts for oxygen reduction reaction: a mini-review

Electrocatalysts for oxygen reduction reaction have been the study of interest because of their importance in various energy storage and conversion reactions. Though platinum-based catalysts are found to be the most active catalysts for oxygen reduction reactions, their high cost and scarcity have led researchers to discover alternative active and cost-effective catalysts. In this regard, heteroatom- and metalloid-doped catalysts were explored as possible alternatives to traditional platinum-based catalysts. Consequently, a large number of heteroatom- and metalloid-doped catalysts have been synthesized and evaluated for oxygen reduction activity. Synergistic catalysts, with dual-doped, tri-doped, and multi-heteroatom-doped catalysts, were also synthesized by doping more than one heteroatom. In this review, we discuss the fundamental principles and reasons behind the origin of ORR catalysis of heteroatom- and metalloid-doped catalysts discussed with the support of literatures.