Self-assembly and photocatalytic properties of clustered and flowerlike CdS nanostructures

Clustered and flowerlike CdS nanostructures were synthesized via the controllable solvent thermal method using ethylenediamine as the structure-directing template. The phase structures and morphologies were measured by X-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD patterns demonstrated that the CdS nanorod cluster sample was hexagonal cell and the flowerlike CdS nanostructure was cubic cell. Experimental results showed that the whole self-assembly process was made-up of nucleation and growth, which was due to the competition in the nucleation. And the template function of ethylenediamine played an important role in the self-assembly. The self-assembly mechanisms of forming the clustered and flowerlike nanostructures were investigated on the basis of the time- and temperature-dependent experiments and were briefly discussed. At room temperature, photoluminescence (PL) spectrum experiments revealed that CdS nanostructures had two visible emission peaks respectively at the wavelengths of 433 nm and nearly 565 nm, which should arise respectively from the excitonic emission and surface-defect. The specific surface areas were characterized by the Brunauer-Emmett-Teller (BET) method. The photocatalysis of clustered and flowerlike CdS nanostructures in methyl orange (MeO) under high-pressure mercury lamp illumination was investigated. The experimental results indicated that the performance of photocatalytic system employing flowerlike CdS nanostructure, with higher specific surface area, was observed to be better than other CdS materials.