Yonghao Wang

CdS/g-C3N4 core/shell nanowires with different g-C3N4 contents were fabricated by a combined solvothermal and chemisorption method and characterized by X-ray powder diffraction, scanning electronic microscopy, transmission electron microscopy, and UV-vis diffuse reflection spectroscopy. The photocatalytic hydrogen-production activities of these samples were evaluated using Na2S and Na2SO3 as sacrificial reagents in water under visible-light illumination (λ≥420 nm). The results show that after a spontaneous adsorption process g-C3N4 is successfully coated on CdS nanowires with intimate contact and can significantly improve the photocatalytic hydrogen-production rate of CdS nanowires, which reaches an optimal value of up to 4152 μmol h(-1) g(-1) at the g-C3N4 content of 2 wt %. More importantly, g-C3N4 coating can substantially reinforce the photostability of CdS nanowires even in a nonsacrificial system. The synergic effect between g-C3N4 and CdS, which can effectively accelerate the charge separation and transfer corrosive holes from CdS to robust C3N4, was proposed to be responsible for the enhancement of the photocatalytic activity and photostability. The possible conditions necessary for the synergic effect to work in a CdS/g-C3N4 core/shell configuration is also discussed.

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.