Hybrid Carbon Sphere Chain–MnO2 Nanorods as Bifunctional Oxygen Electrocatalysts for Rechargeable Zinc–Air Batteries

• Published in: Inorganic chemistry 2023-01, Vol.62 (2), p.989-1000
• Main Authors: Zheng, Xiaoying, Zuria, Alonso Moreno, Mohamedi, Mohamed
• Format: Article
• Language: English
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/acs.inorgchem.2c03916

It is now recognized that the development of self-supported and efficient bifunctional air cathodes via the direct growth of earth-abundant catalysts onto the surface of the conductive collector would be a cutting-edge strategy to reduce interfacial resistance, enhance the mechanical tenure, and reduce the final weight and cost of manufacturing of rechargeable Zn–air batteries (ZABs). This work reports an innovative self-supported precious metal-free electrode, comprising carbon sphere chains (CSCs) directly grown onto a carbon paper (CP) substrate, wherein the CSCs have a functionalized surface bearing carbon nanobud defects, oxygen functional groups, and high-density MnO2 hierarchical nanorods (NRs), uniformly coating the surface of CSCs. Not only is the metal-free functionalized CSC catalyst functional for both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) but its combination with MnO2 NRs impressively enhances the ORR/OER activities. A homemade ZAB assembled with functionalized CSC/MnO2 air cathode can successfully power a timer for a period of 17 days with no voltage loss, whereas two series-connected ZABs can light up 39 red light-emitting diode (LED) bulbs. The self-supported and earth-abundant-based CSC/MnO2 materials open up an opportunity for lightweight and cost-effective ZABs and metal–air batteries in general.