Multilayer hybrid films consisting of alternating graphene and titanium dioxide for high-performance supercapacitors

Abstract

Electrode materials with a three-dimensional (3D) network structure and high-conductivity structural scaffolds are indispensable requirements for the development of in-plane supercapacitors with a superior performance. Herein, the highly tunable thin films with oriented interpenetrating network structures are prepared by the layer-by-layer (LBL) self-assembly technique based on the alternate deposition of negatively charged graphene oxide (GO) and positively charged titanium dioxide (TiO₂), followed by the thermal reduction under an argon atmosphere. The resulting films are characterized by UV visible absorption spectroscopy, atomic force microscopy (AFM), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM) and Raman spectroscopy, which all support the formation of the ordered sandwich framework structures built by graphene nanosheets (GNS) and TiO₂ nanoparticles. Importantly, the multilayer film electrode presents excellent electrochemical capacitance properties, which were also highly dependent upon the deposition sequence and the order of the structural components in the sandwiched film. The significantly improved capacitance of the [GNS/TiO₂]₁₅ film electrode is derived from the unique 3D nanostructure with separated graphene nanosheets, in which the electrochemical double layer formation and dynamic charge propagation could be especially efficient throughout the whole TiO₂ bulk material by providing a smaller resistance and shorter diffusion pathways.