Preparation And Photocatalytic Activity Of The TiO₂/CNTs Composite Film

TiO2/Carbon nanotubes composites can exert the synergistic effects and taketheir respective advantages. Various of applications has been researched in the field ofphotocatalysis, energy materials and sensors. In this paper, TiO2/CNTs composite filmhas been prepared by two-step liquid phase method and gas phase method.TiO2/CNTs composite prepared by liquid impregnation shows a loose blockstructure, TiO2particles agglomerate together to form the main structure and slenderCNT bundles intertwine and link the TiO2blocks. TiO2in composite prepared byin-situ decomposition was well crystallized. Titanium source was introduced to CNTsfilm by steam. TiO2has a uniform diameter and agglomerate together to form acontinuous structure, mainly deposited in the bamboo-like carbon nanotubes or at thejunction of carbon nanotube bundles. Part of surface of the CNT bundles was coatedwith a continuous TiO2layer within10nm.TiO2/CNTs composite was prepared by CVD and the diameter of TiO2was about50-100nm. Most of the TiO2aggregation of spherical particles distributed at thesurface of the CNT bundles.TiO2/CNTs film synthesized by pyrolysis gas method showed a homogeneouscoaxial structure with small-sized and mixed phase TiO2grain uniformly wrapped inCNTs side walls. The crystal phase, grain size and crystalline of TiO2can be ontrolledand the structure is stable. Then we changed the pushing temperature, annealingtemperature, the time of annealing, the kind of titanium precursors and the times ofdeposition to determine the best synthesis conditions. The results showed that whentetrabutyl titanate is subjected to pyrolysis and when pushing temperature is at400-500℃, we obtained the TiO2/CNTs film with both rutile and anatase after heattreatment at400℃for2h, and the diameter of TiO2is5-10nm. The composite canexert synergistic effects and showed enhanced photocatalytic ability. The compositecan degrade80%of methyl orange in0.5h and90%in2h under UV irradiation.