In situ synthesis of CdS modified CdWO4 nanorods and their application in photocatalytic H2 evolution

CdWO4 is a wide band gap semiconductor with relatively high chemical stability and has been widely used as a scintillator material. However, the photocatalytic activity of CdWO4 for H-2 evolution from water is low due to the fast electron-hole combination. In this study, CdS nanoparticles have been grown on the surface of CdWO4 nanorods via an in situ approach and the high photocatalytic H-2 evolution has been realized. The structure, optical properties and morphologies of CdWO4 with different amount of CdS were systematically investigated. Element mapping and high resolution transmission electron microscopy (HRTEM) analysis proved the existence of an interfacial structure between CdS and CdWO4 nanorods and the effect of CdS modification was investigated by photoluminescence spectroscopy. Under UV and visible light irradiation, H-2 was evolved steadily from an aqueous solution containing Na2S and Na2SO3 over this photocatalyst even without noble metal deposition. Moreover, the rate of photocatalytic H-2 evolution over CdS modified CdWO4 is ca. 3.4 and 34 times higher than that of sole CdS or CdWO4 under the same conditions, respectively. The encouraging results presented in this study demonstrate the potential of CdWO4 as a stable photocatalyst for hydrogen evolution from water.