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

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 carriers 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 (E_Fn), which could effectively suppress the surface-capturing process of photo-generated electrons, and improve the intensity and stability of the anode photocurrent.

Key words: inorganic nonmetallic material, transport property of photogenerated carrier, photoelectric property, nanocrystalline TiO₂ film electrode