Abstract

Thin films of transition-metal doped (0.2, 1.0, and 5.0 atom%) TiO2 were prepared on titanium foil using a sol-gel route catalyzed by ammonium acetate. Dopants investigated were the fourth-period transition metals. The prepared films were characterised by Raman spectroscopy, Auger electron spectroscopy, and photoelectrochemical methods. The films doped with transition metals showed a lower photocurrent response than undoped samples. No major red shift in the photocurrent response spectra of the doped films was observed. A photocurrent response was observed under visible light irradiation of the samples and was potential dependent peaking around −0.3 V (SCE), which is indicative of electron promotion from a filled defect level. Examination of the defect level potential dependence by analysis of the current-time response under chopped illumination at fixed potential (−0.8 V–+1.07 V) gave a good correlation with the potential dependence observed in the visible light irradiation studies.