Quantum yields for sacrificial hydrogen generation from saccharides over a Pt-loaded TiO2 photocatalyst

Much attention is paid to sacrificial hydrogen generation from saccharides over a Pt-loaded titanium oxide (Pt/TiO2) from the viewpoint of being a renewable energy alternative to petroleum-based fuels. Here, monosaccharides such as glucose, gluconic acid, galactose, sorbose, fructose, mannose, and disaccharides such as sucrose and cellobiose as well as related compounds such as ascorbic acid and sugar alcohols (xylitol and sorbitol) were used as sacrificial agents (R-H) in order to determine quantum yields (I broken vertical bar) for hydrogen evolution. From double-reciprocal plots of I broken vertical bar to the concentration of R-H, we obtained the limiting quantum yield in an infinite concentration of R-H. The limiting quantum yields were determined to be of similar values (0.058-0.168) for monosaccharides. Moreover, the rate constant (k (R)) for the hydrogen abstraction by hydroxyl radical from saccharides were obtained from the double reciprocal plots. It was found that the k (R) value of glucose was larger compared to galactose, mannose, sorbose, and fructose, which were the stereo and structural isomers of glucose.