Preparation of composition-tunable Cadmium-rich CdS nanotubes and their photocatalytic performance

CdS nanotubes were generally prepared by surfactant or template assisted ways. The compositions of such nanotubes couldn´t be tuned, and especially the yields were usually very low, so that their photocatalysis couldn´t be studied. In this paper, a new photochemical method was introduced to direct synthesize large area cadmium-rich nanotubes by the assistance of air-water interface. Taking CdSO₄ as the cadmium source and Na₂S₂O₃ as sulphur source, a kind of branch-like lamellas with composition difference between the two sides were formed on the precursor surface, under the UV light irradiation. And then the lamellas would bend into ¿test tube¿ like nanotubes by a ¿lamellas bending¿ mechanism. The compositions of such tubes could be tuned by changing the concentrations of precursor solutions. The tube walls were composed of CdS doped with a little of metal cadmium, and the inners were filled with cadmium partly. This kind of nantubes possessed high photocatalytic activity in photodegradation of methyl orange and it could be changed with the composition of nanotubes. This route is simple, low-cost, environment-friend and universal, and can be extended to synsthesize other sulfide and oxide nanostructures.