Recent progress in MnO2-based oxygen electrocatalysts for rechargeable zinc-air batteries

Zinc-air batteries (ZABs) own a great consideration as a promising option for energy storage technology because of their ideal energy density, eco-friendly, inexpensive, and abundant resource. However, the sluggish rates of oxygen reactions on the cathode of ZABs demand the preparation of durable, active, and cost-effective oxygen electrocatalysts. Thus, MnO2-based nanoparticles (NPs) have been investigated as potential oxygen electrocatalysts for ZABs, which have the advantages of high activity, cost-effectiveness, and excellent durability. Hence, this review aims to contribute a general outline of advancements in MnO2-based catalysts most recently. The types and structures of MnO2-based NPs, working mechanism, and electrochemistry of rechargeable ZABs are discussed. Then, different synthesis approaches for MnO2 NPs in rechargeable ZABs application are highlighted and summarized. The synthesis approaches of MnO2-based NPs addressed in this review refer to sol-gel, microemulsion, chemical coprecipitation, rheological phase reaction, solid-phase, template, microwave, redox, hydrothermal, and refluxing routes. The impact of the morphology and composition on MnO2-based NPs in their structural characteristics is summarized. Finally, the current challenges and possible strategies for improving the catalytic activity of MnO2-based NPs as air catalysts for ZABs are discussed in detail. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

This review discusses recent advancements in MnO2-based catalysts, focusing on applications in rechargeable ZABs, synthesis methods, and the influence of morphology and composition on catalytic activity. Challenges and strategies for improving the catalytic activity of MnO2-based NPs as air catalysts for ZABs are also detailed.