Enhanced photocatalytic hydrogen production activities of Au-loaded ZnS flowers.

Au-nanoparticle-decorated ZnS nanoarchitectures were fabricated by a simple hydrothermal approach combined with a deposition-precipitation method. After the deposition-precipitation process, 5-nm Au nanoparticles were homogeneously dispersed on the ZnS surface. In addition, the band gap of ZnS was also narrowed by the incorporation of a small amount of Au(I) ions. The photocatalytic hydrogen production activities of all the samples were evaluated by using Na(2)S and Na(2)SO(3) as sacrificial reagents in water under a 350 W xenon arc lamp. The results show that the photocatalytic hydrogen production rate of ZnS nanoarchitectures can be significantly improved by loading Au cocatalysts and reaches an optimal value (3306 μmol h(-1) g(-1)) at the Au content of 4% wt. Although strong surface plasmon resonance (SPR) absorption of the Au nanoparticles was found in the Au-loaded samples, all of these samples exhibit no activities in the visible light region (λ > 420 nm). On the basis of this Au/ZnS system, the possible roles of Au deposition in improving the photocatalytic hydrogen production activity, especially the necessary condition for SPR effect of metal nanostructures to function in the visible-light photocatalysis, are critically discussed.