Synthesis And Photocatalytic Properties Of Ruthenium-based Photosensitizer In TiO₂ Catalytic System

In this paper, four inorganic-organic photosensitive complexes(Ru-1, Ru-2, Ru-3 and Ru-4) were prepared and used as photosensitizer, and those compounds were sensitized to platinized Ti O2. Four new composite photosensitive catalysts were prepared by sensitizing the above ruthenium complexs on the platinized Ti O2. Several key parameters affecting photocatalytic hydrogen production were optimazed based on the constructed photocatalytic system under visible light(λ>420 nm) irradiation,. Besides, the possible mechanism of hydrogen production was also discussed by the cyclic voltammogram and fluorescence spectra analysis.First, four inorganic-organic photosensitive complexes had been synthesized by the reaction of Ru Cl3·3H2O, salicylic acid with 1, 10-phenanthroline and indole-3-carbaldehyde. And then the structure and properties of these compounds were measured and characterized by IR, MS, NMR, elemental analysis and UV-visible spectra.Second, four composite photosensitive catalysts, such as Ru-1-Pt/Ti O2, Ru-2-Pt/Ti O2, Ru-3-Pt/Ti O2, Ru-4-Pt/Ti O2, had been prepared by sensitizing the ruthenium photo-sensitive complex on the platinized Ti O2 under the conditions with light deposition and impregnation. The study of UV-visible diffuse reflectance spectroscopy proved that the light response scope of Ti O2 in the target composite photosensitive catalysts was expanded to visible light range. Furthermore, the structure and property of four target catalysts were measured and characterized by XRD and SEM-EDS analysis.Finally, under the irradiation of visible light(300 w Xe light source, 420 nm filter), hydrogen production activity of target composite photosensitive catalyst were studied. The effects of the composite photosensitive catalyst dosage, the type of sacrificial agent, p H value and concentration of the sacrificial agent on hydrogen evolution were investigated., the maximum hydrogen production of 1610.79 μmol and the maximum rate of hydrogen evolution of 402.23 μmol/h based on Ru-1-Pt/Ti O2 was obtained over 7 h irradiation under the optimum conditions with p H = 4, the composite photosensitive catalyst dosage of 20 mg, ascorbic acid concentration of 0.3 M in 20 m L water solution. At the same time, we preliminary studied the stability and the deactivation reason of the composite photosensitive catalyst. The cycle experiment showed tthat these composite photosensitive catalysts were relatively stable after 3 circulations. The results showed that deactivation of reaction system was mainly due to photosensitive ruthenium complex desorption from the surface of Ti O2.