Characterization and photocatalytic performance of carbon nanotube material-modified TiO2 synthesized by using the hot CVD process

Carbon nanotube-modified TiO2 was synthesized by using the hot CVD process. Fe (0.13–1.9 wt%) as the catalyst for synthesis of carbon nanotubes modified on the surface of TiO2, was loaded on commercial TiO2 particles. CH4 gas was used as the carbon source in the CVD process. The color of the Fe-supported TiO2 powder changed to black when CVD treatment was performed. Nano-sized spherical carbon materials were generated on the surface of TiO2 after the CVD process. The spherical materials gradually changed to carbon nanotubes with increase in CVD treatment temperature. When the CVD process was performed under optimized conditions, the photocatalytic activity of the carbon nanotube-modified TiO2 was drastically increased. These results indicated that photoexcited electrons might pass through the carbon nanotubes on the surface of TiO2 resulting in improvement in charge separation between electrons and holes generated photocatalytically. For our system, the carbon nanotube materials were grown directly on the surface of TiO2 and this might induce strong interaction between carbon nanotubes and TiO2. Meanwhile, the long-range π electronic conjugation of nanotubes is of benefit to accelerate electron transfer. Thus, the photogenerated electrons of TiO2 are rapidly transported to the carbon nanotube materials bound to the surface of TiO2. The transfer of electrons generated in TiO2 to carbon nanotubes was confirmed by photodeposition of Pt particles by reduction of Pt4+ ions.