Photoelectrochemical studies with n-type Cdo

Abstract

CdO is an inherent n-type semiconductor with a band-gap of ca. 2.3 eV and a flat-band potential located at –0.25 V vs SCE in 0.1 mol dm^–3 NaOH solution. Electrodes fabricated by compressing CdO powder showed an exchange current density of 5 × 10^–8 A cm^–2 for O₂ liberation in 0.1 mol dm^–3 NaOH and this was increased to 9 × 10^–6 A cm^–2 by depositing small amounts of RuO₂ onto the CdO surface. Irradiation of CdO powder suspended in alkaline solution resulted in O₂ formation only when an electron acceptor, such as ferricyanide, was present in solution. The presence of RuO₂ deposits reduced the yield of O₂.