A photoelectrochemical study of CuWO4 single crystals

Single crystals of CuWO, are grown by the flux method using Na2W2O7 as a flux. Semiconducting n-type behaviour, with an activation energy for the electrical conductivity of ΔE = 0.28 eV is obtained by heating under argon flow. The analysis of the spectral response gives two indirect interband transitions at 2.15 and 2.34 eV. The choice of appropriate equivalent circuit for the CuWO4/0.1 N H2SO4, + 0.5 M KCl interface and of appropriate frequency range enables the determination of the space charge capacity. The corresponding Mott-Schottky plots are used to determine the donor concentration (ND = 5.5 × 1019 cm−3) and electron affinity (EA = 4.6 eV) Photon absorption responsible for the electronic transition at 2.34 eV is probably due to a Cu2+ → → W6+ charge transfer, although a competing hypothesis involving a O2- →. Cu2+ charge transfer cannot by absolutely ruled out.