Enhancement of photocatalytic hydrogen production rate using photosensitized TiO2/RuO2-MV2+

Construction of an efficient system for light energy conversion into chemical energy is one of the most important subjects from the viewpoint of solar light energy utilization. Photocatalytic hydrogen production is a promising process for solar energy conversion and storage. As a strategy for effective visible light harvest, spectra sensitization of wide bandgap semiconductors by dye molecules has been studied for photocatalytic H2 production from water. In the present investigation, coupling of an inorganic semiconductor (modified titanium dioxide) with suitable photosensitizers has been studied for photocatalytic hydrogen production. Copper phthalocyanine, ruthenium bipyridyl, and Eosin Y, as photosensitizers were used for hydrogen production using UV/solar radiation. The under-test photosensitizers were added to slurry of TiO2/RuO2 semiconductor containing methyl viologen (MV2+) as an electron relay. It was found that, with sensitized modified titanium dioxide, there is a higher amount of produced hydrogen than with the naked modified titanium dioxide specially in case of using solar energy radiation. Among the under-test photosensitizers, copper phthalocyanine exhibited higher efficiencies compared with other sensitizers. The effect of changing pH on the above system was studied. Suitable mechanisms have been proposed, in accordance with the observations, for the different kinds of catalytic systems employed in the present study.