Copper metal-organic framework-derived CuOx-coated three-dimensional reduced graphene oxide and polyaniline composite: Excellent candidate free-standing electrodes for high-performance supercapacitors

A novel multicomponent hybrid of copper metal-organic framework (MOF)-derived copper oxide@mesoporous carbon (CuOx@mC) embedded with polyaniline (PANI) and reduced graphene oxide (rGO) was synthesized by in-situ polymerization (denoted as CuOx@mC@PANI@rGO). After detailed characterizations of basic chemical and physical performances, the series of as-prepared CuOx@mC@PANI@rGO composites were explored as electrode materials for supercapacitors. Results demonstrated that a uniformly and highly ordered interface layer of PANI together with rGO nanosheets was formed on the surface of the CuOx@mC frameworks because of the regular octahedral structure of CuOx@mC composite. This efficient conductive network can enhance the ion-diffusion process and fast redox reaction at the electrode/electrolyte interface, leading to increased electrical conductivity and enhanced capacitive performance. By changing the pyrolysis temperature of Cu-MOF, the ternary CuOx@mC@PANI@rGO obtained at 700 °C exhibited the highest capacitance of up to 534.5 F g−1 and outstanding cycling stability. Conversely, the corresponding CuOx@mC@PANI showed only a specific capacitance of 456.0 F g-1 at a discharge current density of 1 A g−1. These findings may broaden the applications of metal-organic framework-derived composites as high-performance supercapacitors.