Abstract: In this paper, we used surface photovoltage spectroscopy (SPS) to study the spectral sen-sitization of TiO₂ powders with ZnTPP. It was found that TiO₂ powders (rutile, anatase) modified by ZnTPP show three photovoltaic response bands in the visible range near 420, 550 and 590 nm, which correspond to the Soret, Q(1,0) and Q(0,0) bands of ZnTPP, respectively. These three bands were proved to be the sensitized photovoltage of TiO₂ By ZnTPP, but not the photovoltaic response of ZnTPP itself. It was found that sub-stable anatase is superior to rutile in sensitizing effect. Finally, the photo-induced charge transfer mechanism and feasibility of SPS as a kind of method in studying spectral sensitization were discussed.

Key words: surface photovoltage spectroscopy, spectral sensitization, interfacial charge transfer, zinc-tetraphenyl-porphine (ZnTPP), titanium dioxide