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

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 cm(2) 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.