Three-dimensionally ordered mesoporous Co3O4 decorated with Mg as bifunctional oxygen electrocatalysts for high-performance zinc-air batteries

Developing low-cost and high-efficiency bifunctional catalysts for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is critical to expedite the widespread implementation of rechargeable zinc-air batteries. Herein, a unique Mg-decorated three-dimensionally ordered mesoporous (3DOM) Co3O4 electrocatalyst is engineered and evaluated as cathodic material for zinc-air batteries. The modulation of electronic structure and bonding configuration of Co sites through coordination with substituted Mg atoms effectively enhance the interaction with oxygen species and, therefore, the ORR/OER activity. Meanwhile, the substitution of Co2+ with Mg2+ creates abundant, more catalytically active octahedral sites (Co3+) in 3DOM-MgxCo3-xO4. Moreover, the tailored 3D interpenetrating porous structure endows the electrocatalyst with large diffusion channels for oxygen species and highly accessible active sites. The as-prepared catalyst retains 99% and 98% of its initial ORR and OER current, respectively, after 16 h under chronoamperometric measurement. The zinc-air battery assembled with 3DOM-MgxCo3-xO4 exhibits a high power density of 253 mW cm(-2) and long-term cyclability over 236 h, outperforming the commercial noble-metal based catalysts in terms of performance and stability. This work offers a straightforward and promising design strategy for development of robust bifunctional electrocatalysts toward practical applications of zinc-air batteries.

Automated summary

A unique Mg-decorated three-dimensionally ordered mesoporous (3DOM) Co3O4 electrocatalyst is developed as a low-cost and high-efficiency cathodic material for zinc-air batteries. The modulation of electronic structure and bonding configuration of the Co sites effectively enhances the interaction with oxygen species and improves the activity of the catalyst. The tailored 3D interpenetrating porous structure provides large diffusion channels for oxygen species and highly accessible active sites. The zinc-air battery assembled with this catalyst exhibits high power density and long-term cyclability, outperforming commercial noble-metal based catalysts.