Study On The Ultraviolet Detection And Photoelectric Properties Of Titania Nanotube Arrays

TiO₂nanotubes（TNT）, which possesses unique structure, wide band gap, highphotoelectric activity and so on, has attracted considerable interests due to its wideapplications such as UV detectors. To improve its photoelectric properties, propertymodification methods such as group modification, metal material deposition onto theTNT and so on is an effective method to advance surface resistance andphotoelectrochemical activity. In this paper, hydroxyl modification on the surface ofTNT was carried out by acid treatment with the method of cyclic voltammetry, and Znnanoparticle-TiO₂nanotube composite was synthesized by a pulse electrodeposition（PED） technique. The morphology, structure and composition of hydroxyl modificationof TNT with acid treatment were investigated by field-emission scanning electronmicroscopy （SEM）, X-ray photoelectron spectroscopy （XPS） and X-ray diffraction（XRD）, and the mechanism of hydroxyl modification is also explored. The UVphotoelectric properties of TNT with different concentration of hydrochloric acid anddifferent kinds of acid treatment were investigated by UV-VIS absorption spectrum andaseries of electrochemical tests. The morphology of Zn nanoparticle-TiO₂nanotubecomposites with different calcination atmospheres, temperatures and illuminations werestudied finally. The main results of this paper are as following:①Hydrochloric acid treatment increases the hydroxyl content on the surface of TNTelectrodes, indicating low VIS absorption spectrum indensity and enhanced UVwavelength-selective properties.②The increase of hydroxyl content on the surface of TNT electrodes changes itsFermi energy level, reduces the contact barrier formed between TNT and electrolyteinterface, promote the separation of photogenerated electrons and holes, reduces therecombination of photogenerated electrons and holes and reinforces the chargetransfer from the TNT electrodes to the electrolyte. Hence, the increase of hydroxylcontent can effectively enhance the ability of charge transfer，obviously reducecritical potential of water electrolysis， apparently increase the responsivephotocurrent density and lead to the process of oxidation/reduction of K₃[Fe（CN）₆]from the totally irreversible process to the quasi-reversible process.③Reductive acids are better than oxidative acids used for the acid treatment of TNTelectrodes in changing its Fermi energy level, reducing the contact barrier formed between TNT and electrolyte interface, promoting the separation of photogeneratedelectrons and holes, reducing the recombination of photogenerated electrons andholes and reinforcing the charge transfer from the TNT electrodes to the electrolyte.④Relative to the calcination under air atmosphere, rutile crystalline phase and darkcondition, TNT can receive a better electrical conductivity when TNT is calcinatedunder nitrogen atmosphere, possessing anatase crystalline phase and done with UVillumination. These conditions can reduce surface resistance of TNT, slow down thegrowth of Zn crystal nucleus, reduce the quantity of deposition and minish particlesize of Zn.