Photoelectrolysis of water with two types of semiconductor electrodes which are the Cr-doped single crystal TiO_2, and the Si/TiO_2, heterojunction has been investigated. The Photoresponse of Cr-doped TiO_2, electrode showed longer wave length (visible light region) spectral response than that of non-doped TiO_2, electrode. The visible light response is explained by the formation of the d-band due to Cr-doping below the conduction band edge of the TiO_2, in energy diagram. Photocurrent of Cr-doped TiO_2, electrode, however, decreased. This decrease is mainly due to the structural defects induced in the single crystal TiO_2 by high temperature treatment of Cr-doping resulted in localized deep levels in forbidden band. These deep levels enhance the recombination rate of the photo-generated carriers. The electrode of n-Si/TiO_2, heterojunction was fabricated by coating the Si substrate surface with TiO_2, thin film using CVD technique. The thickness of TiO_2 film determines of the onset potential of photocurrent. The onset potential were shifted to negative potential side with decreasing the TiO_2 film thickness.
半導体電極を用いた水の光電気分解の研究
kiyo34_rikou_pp195-201.pdf
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