Controlled synthesis of porous Co3O4–C hybrid nanosheet arrays and their application in lithium ion batteries

Abstract

Two-dimensional Co₃O₄ nanostructures with porous architectures are experiencing rapid development in functional material fields for their unique structures and properties. Porous Co₃O₄–C hybrid nanosheet (NS) arrays grown directly on various conducting substrates are synthesized by a controlled method for the first time via a facile hydrothermal synthesis approach in combination with heat treatment. These NS arrays reveal uniform hexagonal morphology and have combined properties of quasi-single-crystallinity and a pore network inside the architecture. A four-step formation mechanism is proposed to understand the growth process of nanosheet arrays grown on the substrate based on the change of morphology. Both the concentration of Co²⁺ and poly(vinylpyrrolidone) (PVP) play key roles in the formation of NS arrays. When tested as an anode material in lithium-ion batteries, the porous Co₃O₄–C hybrid NS arrays exhibit improved electrochemical properties of cyclic performance and high coulombic efficiency compared with the commercial Co₃O₄ and Co₃O₄/carbon nanocomposites. This approach, porous Co₃O₄–C NS arrays grown directly on different substrates (wafer, foam, alloy net, foil, especially flexible carbon cloth), provides an efficient route to produce NS arrays to meet the demand for diversity, and may be extended to synthesize other transition metal oxide materials for other applications.