Template-free preparation and characterization of hollow indium sulfide nanospheres

In this manuscript we have demonstrated a template-free route to the preparation of hollow In2S3 nanospheres by solvothermally treating solid In2S3 spheres comprised of small particles at 180 °C for 24 h. This method is simple but highly efficient, which can transform the solid precursors into hollow nanostructures in an extremely high yield. Investigations into the intermediates reveal that the formation of hollow spheres is through the mergence of the smaller particles within the solid spheres by the relatively large ones in the ripening process (i.e., Ostwald ripening). The well crystalline hollow nanospheres have the diameters of 40–70 nm and an average wall thickness of 7 nm. Due to the closeness of the size of hollow nanospheres to the Bohr radius (33.8 nm) of the excition in In2S3, an obvious quantum size confinement and morphology-dependent property are observed. Hollow In2S3 nanospheres show an intense absorption between 318 and 512 nm, which is blue-shifted to shorter wavelengths relative to that of bulk In2S3. Hollow In2S3 nanospheres also exhibit a strong photoluminescence. The green band centered 518 nm is due to the band-band transitions and the orange emission centered at 624 nm originates from the indium interstitial defect. These hollow In2S3 nanospheres could be used as a distinctive multicolored phosphor and material for producing photoelectrochemical devices.