Studies On The Photocatalytic Hydrogen Evolution Using Chloroacetic Acids, Glucose And Sucrose As Electron Donors Over Pt/TiO₂

In this paper, using organic pollutants from waste water as electron donors, the photocatalytic hydrogen evolution and decomposition of the pollutants over Pt / TiO₂ has been investigated. The research works are composed of three parts.Firstly, we studied the photocatalytic hydrogen evolution and decomposition of the pollutants over Pt/TiO₂ in the presence of chloroacetic acids. The experimental results showed that, monochloroacetic acid and dichloroacetic acid enhanced photocatalytic hydrogen generation activity, but trichloroacetic acid did not improve it. The amount of produced H₂ increases almost proportionally to the irradiation time within 5 h irradiation. The photocatalytic oxidation of monochloroacetic acid and dichloroacetic acid mainly produced CO₂, HC1 and CH₂O, the photocatalytic oxidation of trichloroacetic acid mainly produced CO₂ and HCl. The effect of pH value on amount of photocatalytic H₂ generation has been investigated. In chloroacetic acids solution with experimental concentration, the effect of the concentration of monochloroacetic acid and dichloroacetic acid on the reaction rate was consistent with the Langmuir-Hinshelwood kinetic model. The adsorption of monochloroacetic acid and dichloroacetic acid on Pt / TiO₂ has been studied. A possible reaction mechanism was discussed. From the experimental result, it can be concluded that the reaction mechanism of trichloroacetic acid is different from the reaction mechanism of monochloroacetic acid and dichloroacetic acid.Secondly, using glucose and sucrose as electron dornors, we studied the photocatalytic hydrogen evolution over Pt / TiO₂. Glucose and sucrose enhanced photocatalytic hydrogen generation activity. The amount of produced H₂ also increases almost proportionally to the irradiation time within 5 h irradiation. The...