Abstract
A series of Cu(OH)(2)-Ni(OH)(2)/P25 photocatalysts was prepared by co-deposition-precipitation (total metal loading approximate to 1 wt%) and their performance was evaluated for H-2 production. Among this series, the 0.8 Cu(OH)(2)-0.2 Ni(OH)(2)/P25 photocatalyst demonstrated very high H-2 production rates in 20 vol% ethanol/water and 5 vol% glycerol/water mixtures (10 and 22 mmolh(-1)g(-1), respectively). Detailed analyses based on reaction kinetics, photoluminescence, X-ray photoelectron spectroscopy (XPS), and charge carrier scavenging suggest that both working catalysts are composed of Cu and Ni metals in their active phases. Cu-0 is produced directly by the transfer of electrons from the conduction band of TiO2 to surface Cu(OH)(2) nanoclusters, whereas Ni-0 is formed indirectly through a process of gradual dissolution of Ni(OH)(2) to yield aqueous Ni2+ owing to the acidic environment of the medium, followed by Ni2+ reduction by electrons from the TiO2 conduction band. The high rates of H-2 production that match those obtained with noble metals can be explained owing to a considerably less negative Delta G degrees of Cu oxide formation when compared with that of Ni oxide formation([1]) and higher work function of Ni than that of Cu.([2])