Stability of a Cu_2O photoelectrode in an electrochemical cell and the performances of the photoelectrode coated with Au and SiO thin films

摘要

The photoresponse and stability of Cu_2O films have been examined. Thermodynamic calculations showed that, for Cu_2O, there exists a region of chemical stability potential between -0.218 and -0.489 V(S.C.E) for oxidation and reduction potential, respectively. In an aqueous solution, a deterioration in power output occurs at a rate of 50% per day. To stabilize the photocurrent, thin deposits of Au and SiO films onto Cu_2O electrodes have been studied. For the Au deposition, the photocurrent was either quenched or reduced. For the SiO deposited photoelectrode, its effect was to decrease the quantum efficiency of Cu_2O. However, the deposition does not affect the band gap at 2.11 eV (which ensued for an uncoated sample).