Hydrazine-Induced Synthesis of CdS Nanorings for the Application in Photodegradation

In this paper, CdS nanorings synthesized by facile hydrazine-induced microwave method for the photodegradation of pollutants has been reported for the first time. Different reaction method, microwave power, the category and dosage of pH regulating reagent, reaction temperature and reaction time were investigated. The formation of CdS nanorings from the self-assembly of nanoparticles was attributed to the coordination of hydrazine producing the dipole-dipole interaction among the uniform nanoparticles obtained by microwave method. The crystal phase, composition, morphology and surface property of CdS nanorings were characterized. The results showed that 100 nm-sized wurtzite CdS nanorings with positive surface charges formed by the self-assembly of 5–8 nm nanoparticles, which presented mesoporous structures with maximum pore size of 52 nm. To study the influence of ring-like structures on the photocatalysis, the photodegradation of rhodamine B (RhB) by CdS nanorings and nanoparticles were compared. The results showed that, CdS nanorings displayed higher photodegradation efficiency, which were originated from favorable band edge potential and obviously more effective electron-hole separation producing more superoxide radical and holes as active specifies. The photodegradation path of RhB contains the process as the demethylation, the decarboxylation process, the chromophore cleavage and ring-open reactions. Finally, the available photodegradation of multiple pollutants and reusability of CdS nanorings were carried out.