摘要
采用sol-gel法制备了均匀透明的锐钛矿相纳米TiO2薄膜电极.通过瞬态光电流谱研究了液相电解液中所制备电极内光生载流子的传输特性.结果表明:在TiO2/电解液界面处,TiO2颗粒表面存在两种能够捕获光生电子的表面态.一种是O2吸附所形成的浅能级表面态(So),能级位于导带下0.5eV以内,其捕获光生电子的起始电位约为-0.4V;另一种是晶格氧离子形成的深能级表面态(Sc),能级位于带隙中部,起电子-空穴对复合中心的作用.二者对光生电子的捕获效率与电解液pH值及电极电位(U)有关.高于0.4V的电位能够显著增大光生载流子的传输速率,降低TiO2薄膜费米能级(EFn),有效抑制表面态对光生电子的捕获,进而提高阳极光电流的大小和稳定性.
The anatase-type nanocrystalline TiO2 film electrode with characteristics of uniformity and transparency was prepared by sol-gel method. The transport properties of photo-generated carders in the prepared electrode contacted with aqueous electrolyte were studied by transient photocurrent spectra. The results show that there exist two kinds of surface states on the TiO2/electrolyte interface. One （shallow surface state）, created by chemisorbed oxygen molecule, locates in the range of 0.5 eV which is just below the conduction band, and its electron-capturing onset potential is about -0.4 V. The other （deep surface state）, formed by lattice oxygen ion, locates near the middle of the band gap, and plays a role as a center for electron-hole surface recombination. The electron-capturing efficiencies of these two surface states are related to the pH value of the electrolyte and the electrode potential （U）. A potential higher than 0.4 V can remarkably increase the transfer rate of photo-generated carriers and make a downward shift of the TiO2 film＇s Fermi level （EFn）, which could effectively suppress the surface-capturing process of photo-generated electrons, and improve the intensity and stability of the anode photocurrent.
出处
《化学学报》
SCIE
CAS
CSCD
北大核心
2006年第17期1761-1764,共4页
Acta Chimica Sinica
基金
国家自然科学基金(No.60274040)资助项目.
关键词
无机非金属材料
光生载流子传输特性
光电特性
TiO2纳米薄膜电极
inorganic nonmetallic material
transport property of photogenerated carder
photoelectric property
nanocrystalline TiO2 film electrode
