Ag-decorated highly mesoporous Co3O4 nanosheets on nickel foam as an efficient free-standing cathode for Li-O2 batteries

Abstract

Highly mesoporous cobalt oxide nanosheets are grown on nickel foam (M-Co3O4/NF) by a hydrothermal method. Ag nanoparticles with 10–50 nm diameters are uniformly distributed on the surface of the mesoporous Co3O4 nanosheets (Ag/M-Co3O4/NF) after chemical bath reaction. Moreover, we discovered that the homogeneous distribution of Ag nanoparticles on free-standing, highly mesoporous Co3O4 nanosheets showed the synergistic effect of the high electrocatalyst reactions toward the ORR from Ag and OER from M-Co3O4. Highly mesoporous Co3O4 nanosheets with a thickness of 10 nm as free-standing cathode for Li-O2 battery are beneficial to accommodating insoluble discharge products and facilitating oxygen diffusion and electrolyte impregnation. Ag nanoparticles can improve the electrical conductivity of the O2 electrode and provide a catalytic activity for ORR at the same time. The Ag/M-Co3O4/NF exhibited a robust catalytic activity as cathode for Li-O2 batteries with a high reversible capacity of 2471.1 mA h g−1, a low discharge/charge overpotential, and a cycle life of 124 cycles (under the curtaining capacity of 500 mA h g−1). The preliminary results indicate that Ag/M-Co3O4/NF is an efficient and stable bifunctional cathode for Li-O2 batteries.