Dye sensitized hydrogen evolution from water

Photochemically stable catalysts for continuous production of dihydrogen from water in the presence of visible light are yet to be developed. Most of the proposed systems suffer from loss of activity with use, at varying extent. In the present investigation, the photoactivity of Pt/TiO2 system in the visible region is improved by the addition of the sensitizer ([Ru(dcbpy)2(dpq)]2+) [where dcbpy=4,4′-dicarboxy 2,2′-bipyridine and dpq=2,3-bis-(2′-pyridyl)-quinoxaline] leading to efficient water reduction. This system is relatively inexpensive, reproducible, extremely stable and efficient in conversion of light into dihydrogen in aqueous solution. In order to obtain maximum information about the performance of TiO2–Pt catalysts, we varied the components and conditions of the system for water reduction. The dependence of the dihydrogen evolution rate on the amount of catalysts, concentration of the sensitizer and percentage of platinum on TiO2 has been studied. In addition to the above, a comparative study on the photocatalytic activities of Pt/TiO2 and Pt/ZnO in the presence of the above sensitizer for the production of hydrogen was also made.