Preparation and photoelectric properties of p-CaFe2O4/n-WO3 composites

Composites of p-CaFe2O4/n-WO3 are prepared via a sol-gel technique. Their structures and optical properties are characterized with X-ray diffraction, scanning electron microscopy and UV-vis absorption spectroscopy. The photoelectric characteristics are investigated by surface photovoltage spectroscopy combined with electric field induced surface photovoltage spectroscopy. The results indicate that CaFe2O4 can well form a p-n type composite with WO3, and the intensity and spectral region of surface photovoltaic response for the composites are strongly dependent on the molar ratio of two components. The enhancement in photoelectric properties and the effective separation of photogenerated carriers could be attributed to the energy level matching between the two components, multielectron process and the high migration rate in WO3. (C) 2012 Elsevier B.V. All rights reserved.