CuAlO2TiO2 heterojunction applied to visible light H2 production

CuAlO2/TiO2 heterojunction was prepared and studied for its potential application as dispersed photoelectrode capable to generate H-2 under visible light. Transport properties of delafossite CuAlO2, i.e. thermoelectric power and electrical conductivity were studied and correlated to an optical and photoelectrochemical characterization to establish energetic diagram of the heterosystem CuAlO2/TiO2. The valence and the conduction bands were estimated to be respectively of -0.05 and of -1.34 V/SCE, which permit electron injection from activated CuAlO2 to an activated TiO2. This fact permitted a physical separation of charge carriers. Photocatalytic experiment performed using S2- and S2O32- showed efficiency respectively of 5265 and 60 mu mol and then after 40 min of irradiation by visible light. The ideal heterojunction composition was CuAlO2 (300 mg)/TiO2 (75 mg). In all cases, the heterosystem was found to be more efficient than CuAlO2 alone whatever the conditions. The optimal pH value was estimated to be of 11. (c) 2006 Elsevier B.V. All rights reserved.