Silica colloidal spheres as metal ions reservoir for synthesis of semiconductor core-shell structure and hollow spheres

Serial semiconductors core-shell and hollow sphere structures were prepared by using silica colloidal spheres as template in alkaline solution. This method presented in this paper involves mainly two steps with metal ions stored into surface layer of silica colloidal spheres in alkaline condition in the first step, followed metal ions reacted with thioacetamide to form semiconductor shell under microwave heating in a short-time. Cadmium ions were used as an example to illustrate the synthesis process. The electron microscopy results suggested that CdS core-shell structure and hollow spheres with complete and uniform shell were successfully synthesized, and the thickness of shell can be controlled in a certain range precisely. The mechanism of this method was discussed in detail. In addition, complex peanut hollow structure was synthesized by using this method, which indicated that this method might be extended to synthesize desired morphology with corresponding silica template. This novel method provides an avenue to synthesize uniform different semiconductor core-shell structure and hollow spheres with controllable morphology and shell thickness.