CORRELATION OF ELECTRON-TRANSFER RATES WITH THE SURFACE-DENSITY OF STATES OF NATIVE AND ANODICALLY GROWN OXIDE-FILMS ON TITANIUM

被引:32
作者
CASILLAS, N [1 ]
SNYDER, SR [1 ]
SMYRL, WH [1 ]
WHITE, HS [1 ]
机构
[1] UNIV WISCONSIN,DEPT CHEM ENGN & MAT SCI,MADISON,WI 53706
关键词
D O I
10.1021/j100171a051
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
We report tunneling spectroscopy (TS) and surface density of states (SDOS) plots ((dI/dV)/(I/V) vs V) for native and anodically grown titanium dioxide (TiO2) films on polycrystalline Ti. The results are compared to data obtained by using single-crystal TiO2 ((001) and (110) surface orientations). SDOS plots for anodically grown TiO2 films (160 angstrom thick) and single-crystal TiO2 show a large bandgap region (approximately 2 eV) with a low state density separating the conduction and valence band edges. The similarity in the distribution of SDOS for anodically grown TiO2 films and single-crystal TiO2 indicates that the anodically grown film has a well-ordered rutile structure. In contrast, SDOS plots obtained on native TiO2 films show a nearly constant density of states over a 5-eV range and a approximately 20-50-fold increase in state density at energies corresponding to the bandgap region of anodically grown films and single-crystal TiO2. Electron-transfer rates for the oxidation of ferrocene in acetonitrile at native and anodically grown TiO2 films are reported and correlated with the measured SDOS of these materials.
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页码:7002 / 7007
页数:6
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