Preparation of narrow band gap V₂O₅/TiO₂ composite films by micro-arc oxidation

Qiang Luo1), Xin-wei Li1), Qi-zhou Cai1), Qing-song Yan2), and Zhen-hua Pan1) 1) State Key Lab of Material Processing and Dies & Mould Technology, Huazhong University of Science and Technology, Wuhan 430074, China 2) National Defense Key Disciplines Laboratory of Light Alloy Processing Science and Technology, Nanchang Hangkong University, Nanchang 330063, China

摘 要：V2O5/TiO2 composite films were prepared on pure titanium substrates via micro-arc oxidation （MAO） in electrolytes consisting of NaVO3. Their morphology and elements were characterized by scanning electron microscopy （SEM） and energy-dispersive X-ray （EDX） analysis. Phase composition and valence states of species in the films were characterized by X-ray diffraction （XRD） and X-ray photoelectron spectroscopy （XPS）. Ultraviolet-visible diffuse reflectance spectra （UV-Vis DRS） were also employed to evaluate the photophysical property of the films. The V2O5/TiO2 composite films show a sheet-like morphology. Not only V2O5 phase appears in the films when the NaVO3 concentration of the electrolyte is higher than 6.10 g/L and is loaded at the surface of anatase, but also V4+ is incorporated into the crystal lattice of anatase. In comparison with pure TiO2 films the V2O5/TiO2 composite films exhibit significantly narrow band gap energy. The film prepared in an electrolyte consisting of NaVO3 with a concentration of 8.54 g/L exhibits the narrowest band gap energy, which is approximately 1.89 eV. The V2O5/TiO2 composite films also have the significantly enhanced visible light photocatalytic activity. The film prepared in an electrolyte consisting of NaVO3 with a concentration of 8.54 g/L exhibits the best photocatalytic activity and about 93% of rhodamine is degraded after 14 h visible light radiation.

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