Advanced noble-metal-free bifunctional electrocatalysts for metal-air batteries

The sluggish reaction kinetics at the oxygen cathode is one of the important issues hindering the commercialization of the metal-air batteries. Although the noble metal can be used as the high-efficiency electrocatalyst to solve the problems to some extent, the high cost and scarcity of these noble-metal catalysts have limited their application in electrocatalysis. In this review, we discussed the mechanisms of the ORR and OER, and proposed the principles for the bifunctional electrocatalysts firstly, and then the state-of-the-art bifunctional catalysts, including carbon-based materials and transition-metalbased materials. On the basis of that, the self-supporting 3D noble-metal-free bifunctional ORR/OER catalysts were also discussed. Finally, the perspectives for the bifunctional electrocatalysts were discussed. (C) 2021 The Chinese Ceramic Society. Production and hosting by Elsevier B.V.

Automated summary

This review focuses on the sluggish reaction kinetics at the oxygen cathode in metal-air batteries, which is a major obstacle to their commercialization. The use of noble-metal electrocatalysts has been a potential solution, but their high cost and scarcity hinder their widespread application. The review discusses the mechanisms of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), proposes principles for bifunctional electrocatalysts, and presents state-of-the-art catalysts based on carbon and transition-metal materials. Additionally, it explores self-supporting 3D noble-metal-free bifunctional ORR/OER catalysts and provides perspectives on the future development of bifunctional electrocatalysts.