A three-dimensional TiO.sub.2/graphene porous composite with nano-carbon deposition for supercapacitor

Titanium dioxide/graphene composite is receiving intensive attention because of its potential applications in energy field. Herein, we report the preparation of a three-dimensional TiO.sub.2/graphene porous composite prepared by using a sacrificial template strategy, avoiding the usual hydrothermal and freeze-drying processes. Graphene oxide sheets and TiO.sub.2 nanoparticles were first dispersed in a block copolymer micelle solution, and then the mixture was exposed to a non-solvent vapor atmosphere to evaporate the solvent. Finally, the resultant intermediate product was calcined in nitrogen to remove polymer template. As a result, the obtained free-standing composite material has a three-dimensional porous microstructure. Scanning electron microscopy and transmission electron microscopy observations indicate that the composite is supported by TiO.sub.2-anchored graphene sheets. More interestingly, nano-carbon particles derived from the carbonization of the polymer template are evenly deposited onto both the graphene sheets and the TiO.sub.2 nanoparticles. The specific capacitance of the carbon/TiO.sub.2/reduced graphene oxide composite has been measured to reach 23.6 mF/cm.sup.2. Our results indicate that the enhanced electrochemical properties of the composite are attributed to a synergistic effect of the 3-D porous network and the unique microstructure. The electrochemical stability and the cycle performance of the obtained composite electrode are tested to illustrate its potential applications.