Preparation of anodized TiO2 photoanode for photoelectrochemical hydrogen production using natural seawater

Water shortages are anticipated to occur all over the world and are likely to have a significant effect on the availability of water for water splitting processes, such as photocatalysis and electrolysis, as well as for drinking and industrial water. To overcome this problem, it has been suggested that seawater could be used as an alternative resource for the various water industries, including hydrogen production, industrial, and drinking water. Seawater contains a large amount of dissolved ion components, thus allowing it to be utilized as an electrolyte in PEC systems for producing hydrogen. In this study, anodized TiO2 electrodes are prepared and used as the photoanodes in a photoelectrochemical (PEC) system designed to convert natural seawater into hydrogen with the assistance of an external bias, and their electrochemical and morphological properties were characterized, and correlated with the hydrogen evolution rate and photocurrent. In order to prepare light sensitized TiO2 electrodes, titanium was anodized in single and mixed chemicals and annealed under various conditions. Based on the comparison of their electrical and physical properties and hydrogen evolution rate, the TiO2 electrode anodized in a mixture of chemicals (NH4F-H2O-C3H8O2 (ethylene glycol)) showed the best performance among the other electrodes. The experimental results showed that the hydrogen evolution rate obtained using seawater in the PEC system is ca. 215 mu mol/cm(2) h, thus confirming that this is an effective seawater electrolyte for hydrogen production, and the optimum external bias supplied by the solar cell is at least 3.0 V. (C) 2010 Elsevier B.V. All rights reserved.