Quantum efficiency of Cu2O electrode in photoelectrochemical cells with and without bias

The photoresponse of a p-type Cu2O him on copper is presented. The current-voltage characteristics exhibit a large photocurrent with an onset potential at cn. -0.2 V (S.C.E.). The electrode in the Cu2O/Pt biased cell shows high quantum efficiency which is approaching 100% for wavelength lambda approximate to 300 nm. Studies show that even for potentials just slightly more negative than V-on, the quantum efficiency is relatively large. This result may be explained either by a current doubling phenomena or could be due to a contribution to additional band gaps which may er;ist at higher energies. The overall high quantum efficiencies, moreover, can be obtained without the use of any external bias if a TiO2 counter electrode is used. (C) 1997 Elsevier Science Ltd.