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Preparation of spherical TiO 2 films , and photoelectrochemical properties of the modified

Author: ZhangZuoJuan
Tutor: LiJie
School: Central South University
Course: Physical and chemical
Keywords: TiO2 film spherical particle doping Fe modification photoelectrochemistry
CLC: O614.411
Type: Master's thesis
Year: 2011
Downloads: 51
Quote: 0
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Abstract


Among various oxide semiconductors, titanium dioxide (TiO2) has properties of non-toxic, high catalytic activity, optimum chemical stability and high refractive index. However, fast recombination rate of photogenerated electron-hole pairs in the bulk TiO2 and the low quantum yield of photochemical conversion for solar severely hinder the industrial applications of TiO2 semiconductor material. In this study, five chemical materials, i.e., tetrabutylortitanate, ice acetic acid, polyvinylpyrrolidone (PVP), urea and ferric nitrate, were used as raw material. The TiO2 film, N- TiO2 film and Fe/N- TiO2 film with spherical particles on surface were prepared by sol-gel method and pulse electrodeposition. The TG-DSC, XRD, SEM, UV-Vis absorption spectroscopy and photocurrent spectroscopy analysis were performed to characterize the morphology, crystalline phase, photo-absorption ability and photoelectrochemical property of the sample. The main results are outlined as following:Firstly, the effects of PVP contents and sintering temperature on microstructure and photoelectrochemical properties of TiO2 films were investigated. The TiO2 films with spherical particles of size about 100-200 nm were synthesized after heat treatment at 500℃for 1 hour by adding 1 g PVP. Spherical particle size reached～250 nm and the surface was smooth when films were prepared at 400℃. The grain size becomes smaller and the surface of the grain is rougher with the increase of heat treatment temperature. In addition, photocurrent becomes higher firstly and then becomes lower with the increase of heat treatment temperature. The photocurrent reached the maximum value when treated at 500℃. The photocurrent of N-TiO2 films calcined at 400℃,500℃,600℃are 0.23,0.42 and 0.31 mA/cm2 respectively.Furthermore, the nitrogen-doped TiO2 film was fabricated by sol-gel method using urea as N source. The result indicates that inducing of N has no effect on morphology of film. Optical response of TiO2 sample with 4% N extended to over 600 nm in visible light area. In comparison to undoped TiO2, the N-doped samples show a significant enhancement in photoresponse with photocurrent increase of 1 time at 1.0 V (vs Ag/AgCl).Finally, to further improve photoelectric conversion efficiency, we have fabricated Fe-doped N-TiO2 film by pulse voltage electrodeposition. The effects of Fe content on photoelectrochemical properties of N-TiO2 films were investigated. The results show that ferric can be doped successfully onto TiO2 photoelectrodes by controlling deposition current, and the Fe/N-TiO2 film show significant enhancement in photoresponse with photocurrent increase of 50%.

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CLC: > Mathematical sciences and chemical > Chemistry > Inorganic Chemistry > Metal elements and their compounds > Section Ⅳ group metal elements and their compounds > The titanium Vice family ( IV B group metal elements) > Ti Ti
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