Photocatalytic hydrogen generation from water under visible light using core/shell nano-catalysts

摘要

A microemulsion technique was employed to synthesize nano-sized photocatalysts with a coren(CdS)/shell (ZnS) structure. The primary particles of the photocatalysts were around 10 nm,nand the mean size of the catalyst clusters in water was about 100 nm. The band gaps of thencatalysts ranged from 2.25 to 2.46 eV. The experiments of photocatalytic H2 generation showednthat the catalysts (CdS)x/(ZnS)12x with x ranging from 0.1 to 1 were able to produce hydrogennfrom water photolysis under visible light. The catalyst with x ?0.9 had the highest rate ofnhydrogen production. The catalyst loading density also influenced the photo-hydrogen productionnrate, and the best catalyst concentration in water was 1 g L21. The stability of the nano-catalystsnin terms of size, morphology and activity was satisfactory during an extended test period for anspecific hydrogen production rate of 2.38mmolg21 L21 h21 and a quantum yield of 16.1% undernvisible light (165W Xe lamp, l . 420 nm). The results demonstrate that the (CdS)/(ZnS) core/shellnnano-particles are a novel photo-catalyst for renewable hydrogen generation from water undernvisible light. This is attributable to the large band-gap ZnS shell that separates the electron/holenpairs generated by the CdS core and hence reduces their recombinations.