Facile synthesis of MnO₂/rGO/Ni composite foam with excellent pseudocapacitive behavior for supercapacitors

In this study, the MnO₂/reduced graphene oxide/Ni (MnO₂/rGO/Ni) composite foam as a binder-free supercapacitor electrode was prepared by a facile method. The rGO film has been firstly coated on the skeletons of Ni foam current collectors by chemical deposition method and that have been used as substrates for preparation of a novel three dimensional rGO/Ni composite foam-supported porous MnO₂ film by the hydrothermal method. The structure of MnO₂/rGO/Ni composite foam was characterized by Raman spectra, IR spectra and Scanning electron microscopy. It indicated that the high-quality rGO film have been coated on skeletons of Ni foam current collectors and the MnO₂ film had a 3D network microstructure, consisting of interlaced nanosheets. Furthermore, the binder-free MnO₂/rGO/Ni composite foam electrode has been characterized by the cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectra. It exhibited excellent pseudocapacitive behavior with specific capacitance of 479.0 F/g. The capacitance could retain about 83.5% after 1000 charge–discharge cycles. This simple synthetic approach provides a convenient route for the large scale preparation of 3D porous MnO₂/rGO/Ni composite foam for lots of applications in future. - Graphical abstract: The MnO₂/rGO/Ni composite foam was prepared by a facile method as shown in Fig. 1 and the unique structure of composite foam was suited to be a binder-free supercapacitor electrode due to low resistance, 3D network and porous structure. - Highlights: • The MnO₂/rGO directly grown on Ni foam was firstly reported. • The MnO₂/rGO/Ni composite foam was prepared by a facile method. • The MnO₂/graphene/Ni composite foam as a binder-free supercapacitor electrode exhibited excellent pseudocapacitive behavior