Hetero Atom Doped Graphene Nanoarchitectonics as Electrocatalysts Towards the Oxygen Reduction and Evolution Reactions in Acidic Medium

Abstract

Oxygen electrocatalysis plays a vital role in sustainable energy solutions concerning the storage and conversion using electrical energy into chemical energy and vice versa. The important processes in oxygen electrocatalysis includes oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) remain clean affordable efficient and economically feasible solutions. Carbon based metal-free materials owing to their abundance, electrical conductivity, porosity, structural modification at the molecular levels and exceptional stability under harsh conditions are emerging as advanced electrodes toward the design of high-performance oxygen electrocatalysts. This review provides a critical overview of this rapidly developing field including the design of efficient hetero atom doped graphene-based metal-free catalysts, defect engineering and co-doping with special emphasis on the electrochemical activity in acidic media. The latest trends in the design of hetero atom doped graphene nanoarchitectonics for ORR and OER along with important electrochemical parameters in the field were also outlined. Furthermore, the design of efficient and robust bi-functional hetero atom doped graphenes elucidating structure-property relationship toward multifunctional OER/ORR behaviour was highlighted. The key challenges and future opportunities in this exciting field are profoundly discussed. Graphic Abstract