Preparation of Carbon-Nanotube-supported TiO2for Enhanced Dye-degrading Photocatalytic Activity

Titanium dioxide–carbon nanotube ( TiO 2 ‐CNT ) nanocomposites were successfully synthesized by a sol–gel method. The prepared TiO 2 ‐CNT samples were characterized by transmission electron microscopy ( TEM ), X‐ray photoelectron spectroscopy ( XPS ), and X‐ray diffraction ( XRD ). The photocatalytic activity of the samples was tested by photodegradation of methylene blue ( MB ) and methyl orange ( MO ) in aqueous solution under UV ‐light irradiation. In the photocatalytic results, the TiO 2 ‐CNTs , as compared to the pristine TiO 2 and commercial P25 TiO 2 photocatalysts, exhibited the fastest degradation performance in both dye solutions. The TiO 2 ‐CNTs ’ apparent rate constants were 0.0232 and 0.0214 min –1 in the MB and MO solutions, respectively, both of which are approximately 5 times greater than that for the commercial P25 TiO 2 ( MB : 0.0046 min –1 , MO : 0.0043 min –1 ). And as for the estimated electron‐transfer resistance ( R ct ) results from the ac impedance spectra, the values increased in the following order: TiO 2 ‐CNT < P25 TiO 2 < pristine TiO 2 , indicating that CNTs can serve as electron‐transmitting paths, thus suppressing the recombination rate of photogenerated electron/hole pairs. Moreover, the degree of photodegradation inhibition was insignificant in the presence of interfering anion species (1000‐fold).