ZnS Nano‐Spheres Formed by the Aggregation of Small Crystallites and Their Photocatalytic Degradation of Eosin B

Abstract

Monodispersed ZnS nano‐spheres were synthesized by a simple precipitation. By adjusting the concentration of Zn and S sources, the particle size and morphology were easily controlled. Careful examination of the obtained particles suggested porous structures composed of building blocks of small crystallites, ca. 4–13.4 nm in diameter. A higher [S]/[Zn]‐precursor ratio resulted in a bigger crystallite size but a smaller particle size, and vice versa, for the lower precursor ratio. However, an extreme [S]/[Zn] ratio of 20 provided no spherical aggregation, but a formation of amorphous aggregates. We consider the rate to nucleation and the diffusion‐controlled aggregation of crystallites to be important parameters in determining particle sizes and size distributions. Size homogeneity of the obtained ZnS nano‐spheres, especially with a [S]/[Zn]‐precursor ratio of 5, afforded a photonic crystal array that can potentially benefit the photocatalytic activity. When the photocatalytic activities of the ZnS nano‐spheres obtained via different conditions were compared, it was found that spherical aggregation and high surface areas have a positive effect on catalytic activity. Although using a [S]/[Zn] ratio of 20 provided the highest surface area, the amorphous aggregation and overly excessive use of S caused a detrimental influence on the catalytic activity.