二氧化钛纳米管阵列薄膜的超声辐射阳极氧化制备

Supersonic Anodization Preparation of Thin Titanium Oxide Nanotube Arrays Films

通过使用铂片作为对电极在含有氢氟酸的二甲基亚砜溶液中,将金属钛片进行阳极氧化的方法制备得到二氧化钛纳米管阵列薄膜.在施加40 V偏压超声辐射作用下阳极氧化24 h条件下得到的二氧化钛纳米管长达到680 nm,管内直径25 nm,管壁厚度约3～5 nm.采用了XRD和TEM等分析手段表征了二氧化钛纳米管阵列薄膜的微观结构和表面形貌,分别测试了薄膜的光吸收性能、循环伏安特性和光化学转换效率,并和碱性溶胶-凝胶方法制备的纳米晶二氧化钛薄膜作了对比研究.实验制备的二氧化钛纳米管阵列薄膜电极的光吸收率比纳米晶二氧化钛薄膜提高了40%,光电化学转换效率前者是后者的6倍,实验结果表明二氧化钛纳米管阵列薄膜结构有利于加快电子的传输,并能减少电荷复合,采用这种二氧化钛纳米管阵列薄膜结构的染料敏化太阳能电池光电极有望进一步提高太阳能电池的效率.本文还探讨了在超声波辐射作用下二氧化钛纳米管阵列薄膜的形成机理.

Thin titanium oxide nanotube arrays（TNAs） films were synthesized by supersonic anodization of titanium foil in an aqueous dimethyl sulfoxide solution containing HF.After anodization,TNAs up to 680 nm in length,25 nm inner pore diameter,and 3～5 nm wall thickness were obtained.Their microstructure and surface morphologies were characterized by XRD and TEM.The optical absorption performances,cyclic voltammograms characteristics and light chemical conversion efficiencies of these films were tested.The results implied that the TNAs films have an outstanding accelerated electronic transportation and compressed recombination rate.Electrodes applying such kind of titania nanotubes will have a potential to further enhance the TNAs-based dye-sensitized solar cells efficiencies.The sonoelectrochemical mechanism of TNAs films formation was discussed along with the characterization and analysis of their films morphologies.TNAs were grown from a starting titanium sheet（20～50 mm wide,99.9% purity） degreased by super-sonicating in 1∶1 acetone and ethanol,followed by rinsing with deionized water and drying in air.Electrochemical anodization of titanium was carried out using a DC power supply（Chenghua,Shanghai,0～60 V,0～5 A）,interfaced to a computer and equipped with a programmable function to control the current and voltage during an electrochemical process.Anodic films were grown from titanium by 40 V potentiostatic anodization in dimethyl sulfoxide containing 0.5 mol L-1 HF（standard 48% aqueous HF） for 24 h using a platinum foil counter electrode.The as-anodized nanotubes were amorphous,with crystallinity induced by a subsequent 300～600 ℃ anneal for 6 h in an ambient air with heating and cooling rates of 1 ℃/min.Surface morphologies of the TNAs and titania nanoparticles electrodes were studied using a JEM-2010 transmission electron microscopy（Tokyo,Japan）.The crystalline phases were detected and identified by X-ray diffractometer（XRD） on a D8 ADVANCE powder X-ray diffractometer（Bruker,Germany）.The ultraviolet-visible（UV-Vis） absorbance spectra of the samples were measured using a HP-8453 UV-Visible spectrophotometer（Hewlett-Packard,US,1 nm resolution） in combination with a Labsphere RSA-HP-53 diffuse reflectance and transmittance integrator（North Sutton,NH）.