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The effective separation of photogenerated electrons and holes in the TiO2/VO2/TiO2 multilayer film electrodes prepared by a sputtering method is studied, in which a very thin VO2 layer is inserted into the space charge layer of a TiO2 electrode. An enhanced photogeneration is observed by inserting the thin VO2 layer of ~2 nm in thickness at a position where the electric field gradient is considered to be large and by adjusting the Fermi level of the system to the 3d-levels of V (super 4+).

Abstract: TiO2 thin films were prepared by the inductively coupled Ar+-plasma sputtering method. The effects of O2 partial pressure on photoelectrochemical performance of the mainly anatase–TiO2 electrodes were studied. O2 partial pressure systematically affected the carrier density and the current–voltage characteristics of the electrodes. An electrode deposited at lowest O2 partial pressure (11 mPa) showed almost 3 orders of magnitude greater donor density and 4 times larger photocurrent compared to the one deposited at highest O2 partial pressure (52 mPa). The differences in current–voltage characteristics of the electrode samples are discussed on the basis of the space charge layer formation in the electrodes with different carrier densities. [Copyright &y& Elsevier]