AN INVESTIGATION OF THE ELECTROCHEMICAL AND PHOTOELECTROCHEMICAL PROPERTIES OF THE CUPROUS-OXIDE LIQUID-PHASE BOUNDARY

In view of the possible application of cuprous oxide in solar energy c onversion its physical properties and photoelectrochemical behavior of the phase boundary between the Cu2O and liquid have been investigated . The composition of galvanostatically deposited films is pure Cu2O, b ut its structure is disordered. The conductivity is due to carriers ho pping between localized energy states. At room temperature thin Cu2O f ilms behave like n-type semiconductors. On the basis of the experiment al data an energy scheme for the thin oxide semiconductor film is give n. From the representative voltammograms in the dark and under illumin ation it could be concluded that the currents are changed under illumi nation and that photodegradation takes place. Some unusual phenomena a re discussed on the basis of the properties of the thin oxide/electrol yte phase boundary where surface effects are more pronounced than in t he bulk material. The conversion efficiency of the Cu2O photoanode in photoelectrochemical cells is below 1%. An analysis of the causes of t his poor performance is given.