3D (Three-dimensional) sandwich-structured of ZnO (zinc oxide)/rGO (reduced graphene oxide)/ZnO for high performance supercapacitors

3D (Three-dimensional) ZnO (zinc oxide)/rGO (reduced graphene oxide)/ZnO sandwich-structured were synthesized by adding zinc oxide powder to the reaction of graphitic oxide reduction and heating. In this reaction, ZnO nanorods arrays with the size of 20-40 nm grew on both surfaces of rGO sheets directly. Compared with the rGO, the as-obtained ZnO/rGO/ZnO exhibited higher surface area. The electrochemical performance of ZnO/rGO/ZnO electrodes was investigated for energy storage. The maximum specific capacitance of 275 F g(-1) at scan rate of 5 mV s(-1) by chronopotentiometry was achieved for ZnO/rGO/ZnO sandwich-structured in 1.0 M Na2SO4. The hybrid ZnO/rGO/ZnO sandwich-structured exhibited an excellent rate capability and excellent long-term cycling stability as compared with rGO. Such results demonstrated that this ZnO/rGO/ZnO sandwich-structured was a promising candidate of electrode material for high-performance supercapacitor. (C) 2014 Elsevier Ltd. All rights reserved.