Morphology Engineering of Co₃O₄ Nanoarrays as Free-Standing Catalysts for Lithium–Oxygen Batteries

Abstract

The effective shape-controlled synthesis of Co₃O₄ nanoarrays on nickel foam substrates has been achieved through a simple hydrothermal strategy. When they served as the binder- and conductive-agent-free porous cathodes for nonaqueous Li–O₂ batteries, they sufficiently reflect the favorable catalytic characteristic of Co₃O₄ and alleviate the problems of serious pore blocking and surface passivation caused by insoluble and insulating discharge products. In particular, Co₃O₄ rectangular nanosheets exhibit superior electrocatalytic performance comparing with Co₃O₄ nanowires and hexagonal nanosheets, leading to higher specific capacity and better cycling stability over 54 cycles at 100 mA g^–1, which relate to their good pore structure, large specific surface area, and highly active {112} exposed plane, effectively promoting the mass transport and reversible formation and decomposition of discharge products in the cathode. These comparisons further indicate the morphology effect of nanostructured Co₃O₄ on their performances as free-standing catalysts for Li–O₂ batteries, which also have been proved through the further analysis of discharge products on different shapes of Co₃O₄ nanoarrays electrodes