Cellulose Tailored Anatase TiO₂ Nanospindles in Three-Dimensional Graphene Composites for High-Performance Supercapacitors

The morphologies of transition metal oxides have decisive impact on the performance of their applications. Here, we report a new and facile strategy for in situ preparation of anatase TiO₂ nanospindles in three-dimensional reduced graphene oxide (RGO) structure (3D TiO₂@RGO) using cellulose as both an intermediate agent eliminating the negative effect of graphene oxide (GO) on the growth of TiO₂ crystals and as a structure-directing agent for the shape-controlled synthesis of TiO₂ crystals. High-resolution transmission electron microscopy and X-ray diffractometer analysis indicated that the spindle shape of TiO₂ crystals was formed through the restriction of the growth of high energy {010} facets due to preferential adsorption of cellulose on these facets. Because of the 3D structure of the composite, the large aspect ratio of the TiO₂ nanospindles, and the exposed high-energy {010} facets of the TiO₂ crystals, the 3D TiO₂@RGO­(Ce 1.7) exhibited excellent capacitive performance as an electrode material for supercapacitors, with a high specific capacitance (ca. 397 F g^–1), a high energy density (55.7 Wh kg^–1), and a high power density (1327 W kg^–1) on the basis of the masses of RGO and TiO₂. These levels of capacitive performance far exceed those of previously reported TiO₂-based composites.