Nanostructured CdS sensitized CdWO₄ nanorods for hydrogen generation from hydrogen sulfide and dye degradation under...

In this report, CdS nanoparticles have been grown on the surface of CdWO₄ nanorods via an in-situ approach and their high photocatalytic ability toward dye degradation and H₂ evolution from H₂S splitting under visible light has been demonstrated. The structural and optical properties as well as morphologies with varying amount of CdS to form CdS@CdWO₄ have been investigated. Elemental mapping and high resolution transmission electron microscopy (HRTEM) analysis proved the sensitization of CdWO₄ nanorods by CdS nanoparticles. A decrease in the PL emission of CdWO₄ was observed with increasing amount of CdS nanoparticles loading possibly due to the formation of trap states. Considering the band gap in visible region, the photocatalytic study has been performed for H₂ production from H₂S and dye degradation under natural sunlight. The steady evolution of H₂ was observed from an aqueous H₂S solution even without noble metal. Moreover, the rate of photocatalytic H₂ evolution over CdS modified CdWO₄ is ca. 5.6 times higher than that of sole CdWO₄ under visible light. CdS modified CdWO₄ showed a good ability toward the photo-degradation of methylene Blue. The rate of dye degradation over CdS modified CdWO₄ is ca. 7.4 times higher than that of pristine CdWO₄ under natural sunlight. With increase in amount of CdS nanoparticle loading on CdWO₄ nanorods the hydrogen generation was observed to be decreased where as dye degradation rate is increased. Such nano-heterostructures may have potential in other photocatalytic reactions.