Photocatalytic hydrogen evolution from aqueous solutions of glycerol under visible light irradiation

Multiphase photocatalysts Pt/Cd1−xZnxS/ZnO/Zn(OH)2 and single-phase photocatalysts Pt/Cd1−xZnxS were prepared by a two-step technique. The photocatalysts were characterized by a wide range of experimental techniques: X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) combined with energy-dispersive X-ray (EDX) spectroscopy, low-temperature N2 adsorption/desorption, and UV/VIS spectroscopy. The photocatalytic activity was tested in a batch reactor in the reaction of hydrogen evolution from aqueous solutions of glycerol under visible light irradiation (λ > 420 nm). The highest achieved photocatalytic activity was 449 μmol H2 per gram of photocatalyst per hour; the highest quantum efficiency was 9.6% (λ > 420 nm). The activity of the multiphase catalysts was shown to exceed that of the single-phase catalysts by a factor of 2.1, likely because of the heterojunctions between sulfides, oxides and hydroxides.