Fabrication of low dimensional carbon and TiO2 nanotube composites via solution chemical process and their electrical properties

摘要

Low dimensional materials have attracted tremendous attention in recent years in various area and applications. TiO2 nanotubes (TNTs) have received attention in the sensing material due to their unique properties [1]. However, it has rather low electrical conductivities so that enhancing the conductivity might be necessary if they can be used various devices such as sensor material. We have thus investigated a synthesis of low dimension carbon materials and TNT composite via solution chemical process with various carbon ratio (weight ratio of carbon:TiO2, 0:100, 1:100, 10:100 and 100:100). The low dimensional carbon materials such as carbon nanotube (CNT) and graphene oxide (GO) are widely known for 1- and 2-dimensional carbon materials [2]. At first 1d/1d (CNT/TNT) composite have been synthesized via the solution chemical route [1] that has a core shell nanotubular structure (Fig.1a), where CNT core was surrounded by rolled shell form of TNT. Although accurate mechanism of how titania nanotube be formed, one of leading theory is that titania nanosheet rolls up during chemical processing. Obtained CNT/TNT composite seems to support the roll-up mechanism not only scanning electronic microscope images but also X-ray diffraction (XRD) patterns. Meanwhile, 2d/1d (GO/TNT) composite had sheet structure (see Fig.1b), in which TNT decorated on the carbon substrate. These low dimensional carbon/TNT composites exhibited new absorption bands in UV-visible spectra[3]. This could be attributed to the co- existence of rolled-up TNTs and GOs. Electrical resistivity of synthesized CNT/TNT and GO/TNT composites was measured in a powdery form by the 4-probe resistivity test (Van der Pauw Method) at room temperature. The larger amount of carbon exhibited lower resistivity, but small amount of carbon (around wt.1%) also showed a good powder electrical conductivity performance.