Enhancement of photocatalytic performance in degradation of aqueous trichloroethylene and methylene blue by using TiO2 thin film fabricated by cellulose nanocrystals templating and Nb doping

초록

This paper methodically reported the photocatalytic properties of TiO2 thin films with high transparency and a mesoporous structure, which were synthesized by manipulating templating with cellulose nanocrystals (CNC) and doping with Nb. The TiO2 precursors containing CNC and Nb chloride were synthesized through the sol-gel route, followed by spin coating on an indium tin oxide substrate with subsequent calcination for 1 h at 400 degrees C. The porous structure, phase composition, optical and morphological properties, and photocatalytic degradation activity of prepared materials were evaluated. The templated CNC played a major role in generating rod-like porous channels in TiO2 film, providing a mesoporous structure, as well as enhancing the heterogeneous nucleation rate of anatase phase with an average crystallite size of 9.95 nm. The anatase phase was stabilized and the surface area of TiO2 with 76.7 m(2)/g increased up to 127.3 m(2)/g with the aid of CNC templating and Nb doping into the TiO2. The light absorption capacity of the CNC templated TiO2 film doped with 5 at% Nb was significantly higher in the visible region than that of the TiO2 films templated with and without CNC. The CNC templated TiO2 film doped with 5 at% Nb presented a drastic enhancement of the photocatalytic degradation rate of trichloroethylene, which was completely decomposed in 30 min, twice faster compared with the TiO2 film templated without CNC. In the case of methylene blue, the complete decomposition with the CNC templated TiO2 film doped with 5 at% Nb occurred in 120 min, exhibiting the highest photodegradation activity. The photocatalytic performance was influenced by major factors, such as the larger active adsorption sites, strong visible light absorption, and efficient charge transfer, induced by templating with CNC and doping with Nb in TiO2 film.

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