Dispersing and functionalizing multiwalled carbon nanotubes in TiO2 sol.

We report that oxidized multiwalled carbon nanotubes (MWCNTs) can be synchronously dispersed and functionalized in TiO2 sol via an in situ sol-gel process. Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and atomic force microscopy (AFM) were used to characterize the functionalized MWCNTs. The results revealed that the hydrolysis and condensation originated from Ti(OC4H9)4 molecules favor the dispersion of MWCNTs in as-prepared TiO2 sol. Based on the strong interaction between the oxidized MWCNTs and TiO2 sol during the in situ sol-gel process, MWCNT (core)-TiOx (shell) tubular composites and TiO2 nanotubes can be obtained through filtrating, washing, and annealing of this kind of TiO2 sol containing functionalized MWCNTs, as revealed by TEM, XPS, Raman spectroscopy, and redispersion experiment. By casting the dilute dispersion of functionalized MWCNTs onto a hydrophilic Si surface, discrete and individual nanotubes can be observed by AFM.