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

Abstract In this report, CdS nanoparticles have been grown on the surface of CdWO 4 nanorods via an in-situ approach and their high photocatalytic ability toward dye degradation and H 2 evolution from H 2 S splitting under visible light has been demonstrated. The structural and optical properties as well as morphologies with varying amount of CdS to form CdS@CdWO 4 have been investigated. Elemental mapping and high resolution transmission electron microscopy (HRTEM) analysis proved the sensitization of CdWO 4 nanorods by CdS nanoparticles. A decrease in the PL emission of CdWO 4 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 H 2 production from H 2 S and dye degradation under natural sunlight. The steady evolution of H 2 was observed from an aqueous H 2 S solution even without noble metal. Moreover, the rate of photocatalytic H 2 evolution over CdS modified CdWO 4 is ca. 5.6 times higher than that of sole CdWO 4 under visible light. CdS modified CdWO 4 showed a good ability toward the photo-degradation of methylene Blue. The rate of dye degradation over CdS modified CdWO 4 is ca. 7.4 times higher than that of pristine CdWO 4 under natural sunlight. With increase in amount of CdS nanoparticle loading on CdWO 4 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.