Novel beta-NiS film modified CdS nanoflowers heterostructure nanocomposite: Extraordinarily highly efficient photocatalysts for hydrogen evolution

摘要

The compositing of semiconductor based photocatalysts with cocatalysts is a well-known, effective strategy to acquire high hydrogen evolution efficiency, for which their morphology and composition are the concerns of most literatures. However, the contact between them, which has been always difficult to improve, is also a key factor. Here a novel beta-NiS film modified CdS nanoflowers (NiS/CdS NFs) heterostructure nanocomposite (HSNC) was successfully synthesized through a simple one-pot hydrothermal method. The obtained NiS/CdS NFs HSNC has well-constructed integrated structure of strong adhesion between the semiconducting CdS NFs and the co catalyst NiS thin films, displaying good transfer ability to photogenerated electrons and high adsorption to visible light together. Resultantly, the obtained composite presents extraordinarily highly efficient photo catalytic hydrogen evolution, and high chemical and structural stability in aqueous solution containing 20 vol.% lactic acid under visible light. The highest rate for hydrogen production reached a recorded value of about 30.1 mmolh(-1) g(-1) at 25 C among all CdS-NiS composite catalysts, and the highest apparent quantum efficiency was approximately 43% at 420 nm. The growth and photocatalysis mechanisms for the NiS/CdS NFs were proposed.