Low-temperature, template-free synthesis of wurtzite ZnS nanostructures with hierarchical architectures

Hierarchical wurtzite ZnS architectures assembled from nanosheets and nanorods, such as branched flowers and fluffy solid and hollow spheres, have been synthesized by a facile, template-free, low-temperature solution route. The growth of wurtzite ZnS nanostructures at temperatures as low as 4 °C without any organic additives has been realized by the slow reaction between Zn(NH3)42+ and thioacetamide in aqueous (NH4)2SO4–NH4OH solutions. Branched ZnS flowers made of ultrathin nanosheets ~6–10 nm in thickness were produced at 4 °C, whereas fluffy ZnS spheres consisting of radially oriented nanorods were fabricated at 60 °C. Prolonged ageing of the fluffy spheres at 60 °C resulted in the formation of unique fluffy hollow ZnS spheres through a spontaneous hollowing process based on Ostwald ripening.