In situ preparation of CdS decorated ZnWO ₄ nanorods as a photocatalyst for direct conversion of sunlight into fuel and RhB degradation

CdS nanoparticles have been grown on the surface of ZnWO ₄ nanorods via an in situ hydrothermal approach and their photocatalytic activities towards hydrogen (H ₂ ) evolution and dye degradation under solar light have been demonstrated. The structural, optical and morphological studies of CdS@ZnWO ₄ heterostructures with varying contents of CdS have been conducted. High resolution transmission electron microscopy (HRTEM) analysis showed sensitization of CdS nanoparticles (25 nm) on ZnWO ₄ nanorods of diameter 30 nm and length -200 nm. A decrease in the photoluminescence intensity of ZnWO ₄ was observed with increasing amounts of CdS nanoparticles which indicates inhibition of charge carrier recombination. Considering the band gap in the visible region, a photocatalytic study has been performed for hydrogen (H ₂ ) production from H ₂ O and Rhodamine B (RhB) dye degradation under natural sunlight. The rate of photocatalytic H ₂ evolution for CdS@ZnWO ₄ is 105 times higher than that of pristine ZnWO ₄ . Similarly, excellent photocatalytic activity was observed for CdS@ZnWO ₄ (20% CdS) composites against RhB degradation which is 4.7 times higher than that of pristine ZnWO ₄ . With increase in the amount of CdS nanoparticle loading on ZnWO ₄ nanorods, the H ₂ generation rate was observed to be decreased after 15% CdS loading whereas, the dye degradation rate is increased. Such nano-heterostructures may have potential in other photocatalytic reactions.