Low-Dimensional Carbon and Titania Nanotube Composites via a Solution Chemical Process and Their Nanostructural and Electrical Properties for Electrochemical Devices

We report on the synthesis of two-dimensional graphene oxide (GO) and one-dimensional titania nanotube (TNT) nanocomposites as well as one-dimensional multiwall carbon nanotube (CNT) and one-dimensional titania nanotube nanocomposites via a chemical solution process. The morphology, electrical properties, and chemical bonding of each nanocomposite were investigated. The microstructural analysis revealed the formation of one-dimensional core–shell structures and two-dimensional sheet structures for the CNT/TNT and GO/TNT nanocomposite systems, respectively. Tubular titania nanostructures were decorated on the GO nanosheets to form two-dimensional composite structure. We found that the carbon and oxide nanocomposites exhibited strong carbon–inorganic oxide bonding, and both low-dimensional carbon materials contributed to an improvement in the electrical conduction property (electrical resistivity of nanocomposites was approximately 104 Ω·cm) when compared to that of pristine titania nanotubes (106 Ω·cm). The present nanocomposites however had 2 orders of magnitude higher resistivity than the simply mixed powder of CNT and TNT owing to the characteristic morphology consisting of the CNT-core and TNT-shell, that reduced direct contact of CNTs among CNT/TNT nanocomposite powder; notwithstanding, we suggest that carbon addition to titania nanotubes results in enhanced electrical properties and improved semiconducting properties, which are key in the development of small-sized electronic devices.