Easy method for preparing nanocrystalline CdS hollow spheres using miniemulsion droplets as templates

Abstract

CdS hollow spheres with well-controlled morphology and uniform size were successfully prepared using a miniemulsion technique, in which miniemulsion droplets of isooctane prepared with dodecylmercaptane as a co-stabilizer were employed as templates. The SH groups of dodecylmercaptane generated S − ions under alkaline conditions, and further reacted with Cd 2+ ions to form cadmium thiolate around the droplets. The cadmium thiolate then reacted with S 2− ions, stemming from Na 2S⋅9H 2O, to directly form CdS hollow spheres owing to the evaporation of isooctane during the reaction and/or the subsequent drying process. No additional dissolution, calcination or additional surface modification of the templates was needed. The size of the hollow spheres could be tuned by altering the molar ratio of the anionic and non-ionic surfactants, while their shell thickness could be adjusted by changing the amount of co-stabilizer.