Synthesis of α-MnO2 nanowires modified by Co3O4 nanoparticles as a high-performance catalyst for rechargeable Li–O2 batteries

Abstract

The α-MnO₂ nanowires uniformly coated with Co₃O₄ nanoparticles were prepared as a bi-functional catalyst for rechargeable Li–O₂ batteries. The α-MnO₂ nanowires were 5–20 nm in diameter, ranging between 5 and 10 μm in length. And the coated Co₃O₄ nanoparticles were around 5 nm in diameter. The α-MnO₂/Co₃O₄ hybrid had a high specific surface area of 329.5 cm² g⁻¹, and showed excellent catalytic property. Both of the charge and discharge overpotentials are effectively reduced and the batteries could stably work for more than 60 cycles. It is demonstrated that the catalytic performance of the α-MnO₂/Co₃O₄ hybrid is not only associated with the morphology and size of the catalyst, but also with their synergetic effects and the oxygen vacancies produced at the surface of MnO₂. The results of charge–discharge cycling tests demonstrate that this α-MnO₂/Co₃O₄ hybrid catalyst is a promising candidate for the Li–O₂ batteries.