Heteroatom-Doped Carbon Nanotube and Graphene-Based Electrocatalysts for Oxygen Reduction Reaction

Oxygen reduction reaction (ORR) is a key step that determines the performance of a variety of energy storage and conversion devices, such as fuel cells and metal-air batteries. Heteroatom-doped carbon nanotubes (CNTs) and graphenes have attracted increasing interest and hold great promise as efficient ORR catalysts to replace noble-metal-based catalysts, owing to their unique structure characteristics, excellent physicochemical properties, low cost, and rich resources. In this review, recent progress on the design, fabrication, and performance of heteroatom-doped CNT- and graphene-based catalysts is summarized, aiming to provide insights into the working mechanism of these heteroatom-doped nanocarbons in ORR. The advantages, challenges that remain, and possible solutions of these nanocarbon-based electrocatalysts are discussed. Finally, future developing trends of the CNT and graphene-based ORR catalysts are proposed.