Photoelectrochemistry of porous p-Cu2O films

Porous p-Cu2O films were prepared on transparent conductive glass from a dispersion of Cu2O powder in ethanol. Upon illumination with a 100 W tungsten lamp, the photocurrent of the porous Cu2O film was appreciably greater when compared to electrodeposited Cu2O films. The enhancement is attributed to the increased interfacial area between the film and the solution due to the three-dimensional nature of the Cu2O film. No chemical change was detected by visual examination and X-ray diffraction of the porous Cu2O film after illumination for 2 h in the aqueous solution at -0.4 V vs saturated calomel electrode. The reported stability of electrodeposited Cu2O films is attributed to the effect of Cu+-terminated (111) surface, where the W-assisted photoreduction of Cu2O is less likely to occur. The well-known instability of single-crystal Cu2O is hypothesized to be due to the predominating (211) and (311) surfaces, where the photodecomposition to Cu is inevitable at the exposed O2- sites. (C) 2008 The Electrochemical Society.