Synthesis of Nickel Sulfide Submicrometer‐Sized Hollow Spheres Using a γ‐Irradiation Route

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Nickel sulfide (NiS) hollow spheres have been successfully synthesized by γ‐irradiation, at room temperature, of an aqueous PMMA–CS 2 –ethanol solution that contains NiSO 4 ·6H 2 O. Electron microscopy results show that the diameter of the NiS hollow spheres and the thickness of the sphere shells are about 500 nm and 20 nm, respectively. The room‐temperature UV‐vis absorption spectrum of the NiS hollow spheres gives a peak centered at around 233 nm (5.56 eV) with a remarkable blue‐shift relative to that of bulk NiS (2.1 eV). This remarkable blue‐shift may be attributed to the small dimensions of the materials. A possible growth mechanism of NiS hollow spheres by γ‐irradiation method is also presented. The successful preparation of NiS hollow spheres on a large scale under mild conditions could be of interest for both applications and fundamental studies.