solutions were studied by X-ray diffraction, diffuse reflectance UVevisible spectroscopy and field emission scanning electron microscopy. From the characterizations, it was confirmed that Sn can form solid solution with Cd 0.1 Zn 0.9 S and the high crystallinity can be maintained as well. Among all samples, the highest photocatalytic activity was observed on Cd 0.1 Sn 0.01 Zn 0.88 S photocatalyst, with average rate of hydrogen production 3.52 mmol/h, which was ca. 1.5 times higher than the Cd 0.1 Zn 0.9 S photocatalyst. In addition to the high activity, the Cd 0.1 Sn 0.01 Zn 0.88 S also showed high stability at long irradiation time. The role of Sn in preventing electron-hole recombination and photocorrosion was proposed.

a b s t r a c tA series of Cu-doped Cd 0.1 Zn 0.9 S solid solution with various amounts of Cu dopant was successfully prepared by hydrothermal method. The properties and the photocatalytic activity of the prepared samples for hydrogen production under visible light irradiation were compared to those prepared by co-precipitation method. The Cu-doped Cd 0.1 Zn 0.9 S samples prepared by hydrothermal method showed both improved crystallinity and photoabsorption ability as compared to the undoped sample. On the other hand, even though Cu-doped Cd 0.1 Zn 0.9 S prepared by co-precipitation method also showed improved photoabsorption ability in the visible light region, the samples showed poor crystallinity compared to the undoped one. With the same amount of Cu dopant, all samples prepared by hydrothermal method were found to exhibit higher photocatalytic activity for hydrogen production than the samples prepared by co-precipitation method. It was revealed that the amount of Cu dopant, crystallinity and narrow band gap energy are important factors to obtain highly active and stable photocatalysts.

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A series of bimetallic copper-nickel (CuNi x , x ¼ 0.1, 0.2, 0.5 and 1) nanoparticles supported on activated carbon (AC) were prepared by deposition-precipitation method for the oxidation of benzyl alcohol to benzaldehyde using hydrogen peroxide as oxidising agent. Analyses by means of X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) confirmed that Cu and Ni was successfully added on the surface of activated carbon. CuNi 1 /AC showed the best catalytic activity for the oxidation of benzyl alcohols to the corresponding aldehyde within a short reaction period at 80 C. The catalytic performance is significantly enhanced by the addition of equal amount of Ni as compared to the monometallic counterpart. This result indicates the synergistic effect between Ni and Cu particles in the catalytic oxidation reaction.