Synthesis of titania/carbon nanotube heterojunction arrays for photoinactivation of E. coli in visible light irradiation

TiO(2)/multi-wall carbon nanotube (MWNT) heterojunction arrays were synthesized and immobilized on Si(001) substrate as photocatalysts for inactivation of Escherichia coli bacteria. The vertically aligned MWNT arrays were grown on similar to 5 nm Ni thin film deposited on the Si by using plasma enhanced chemical vapor deposition at 650 degrees C. Then, the MWNTs were coated by TiO(2) using dip-coating sol-gel method. Post annealing of the TiO(2)/MWNTs at 400 degrees C resulted in crystallization of the TiO(2) coating and formation of Ti-C and Ti-O-C carbonaceous bonds at the heterojunction. The visible light-induced photoinactivation of the bacteria increased from MWNTs to TiO(2) to TiO(2)/MWNTs, in which the bacteria could even slightly breed on the MWNTs. In addition, the TiO(2)/MWNTs annealed at 400 degrees C showed a highly improved antibacterial activity than the TiO(2)/MWNTs annealed at 100 degrees C. The excellent visible light-induced photocatalytic efficiency of the TiO(2)/MWNTs/Si film annealed at 400 degrees C was attributed to formation of the carbonaceous bonds at the heterojunction, in contrast to the 100 degrees C annealed TiO(2)/MWNTs/Si sample which had no such effective bonds. (C) 2009 Elsevier Ltd. All rights reserved.