▎ 摘　　要

Three-dimensional (3D) hierarchical graphene/TiO2 composite is fabricated by in-situ preparation of mesoporous TiO2 on the 3D graphene (3DG) framework. The 3D graphene/TiO2 (3DG/TiO2) composite exhibits a hierarchical three-dimensional porous structure with mesopore (3.5 nm), macropore (several tens of micrometers to 200 mu m) and a high specific surface area (171 m(2) g(-1)). When used as electrodes for supercapacitor, the 3D graphene/TiO2 composite electrode delivers a specific capacitance of 235.6 F g(-1) at 0.5 A g(-1), whereas that of 3D graphene is 160.4 F g(-1). Furthermore, the 3D graphene/TiO2 electrode exhibits acceptable rate capability (86% capacitance retention at 2 A g(-1)), and satisfactory cycling stability. Asymmetric supercapacitor was further assembled based on the 3DG/TiO2 and activated carbon electrodes. The device possesses a specific capacitance of 64.9 F g(-1) at 0.2 A g(-1). This improved electrochemical capacitive performance is mainly owing to the synergistic effects between graphene and TiO2, and the hierarchical three-dimensional porous structure. (C) 2018 Elsevier B.V. All rights reserved.