Co₃O₄ Hollow Porous Nanospheres with Oxygen Vacancies for Enhanced Li–O₂ Batteries

Creating oxygen vacancies to tune the surface electronic structure is a feasible approach to enhance the electrocatalytic activities of noble-metal-free transition-metal oxides for Li–O2 batteries. Herein, vacancy-rich Co3O4 hollow porous nanospheres have been obtained through a facile reduction strategy from Co3O4 hollow porous nanospheres, which were prepared in a self-template construction manner through a solvothermal synthesis followed by a heat treatment. The reduced Co3O4 hollow porous nanospheres composed of numerous nanoparticles show a unique porous and hollow structure with abundant surface oxygen vacancies. The oxygen vacancy defects can produce more electrochemical active sites and improve the electrical conductivity as well as increase the adsorbed oxygen-containing molecules for the enhanced Li–O2 battery performance. Therefore, the reduced Co3O4 sample with oxygen vacancies shows lower overpotential, higher discharge capacity, longer cycling life, and better rate capability than the pristine one.