Photocatalytic Hydrogen Generation by Pollutant Formaldehyde as Electron Donor over Pt/TiO_2

Using formaldehyde as electron donor, the photocatalytic hydrogen evolution over Pt/TiO\-2 has been investigated. The photocatalytic oxidation of formaldehyde produced carbon dioxide and formic acid which can be oxidized thoroughly. The hydrogen evolution and the degradation of the pollutant formaldehyde can be carried out simultaneously in this reaction system. The photocatalyst was prepared by photodeposition. Optimal amount of Pt deposited on TiO\-2 was 0.5%. Effect of the concentration of formaldehyde on the reaction rate was consistant with the Langmuir\|Hinshelwood kinetic model. Alkaline condition favored this reaction. Containing methanol in formaldehyde solution with lower concentration, the rate of hydrogen evolution increased to some extent. A possible reaction mechanism was discussed.