Evolution of SnO2 nanoparticles into 3D nanoflowers through crystal growth in aqueous solution and its optical properties

Three-dimensional nanoflowers consisting of uniform crystalline SnO2 nanorods were spontaneously grown by the gradual hydrolysis of SnS32− in an aqueous system at 180 °C. The resulting material was characterized by using SEM, TEM, EDX, SAED, XRD, and UV–vis techniques. The results clearly show that these uniform crystalline SnO2 nanorods grow in the [0 0 1] direction with the enclosing facets of {1 1 0}. It is believed that the controlled release of Sn(OH)62− is achieved via the gradual hydrolysis of SnS32−, which is accounting for the oriented growth. The band gap energy (Eg) of the SnO2 nanoflowers deduced from the diffused UV–vis spectrum is 3.60 eV and the photoluminescence spectra of the nanoflowers shows three emission peaks centered at wavelengths of 355, 390 and 465 nm, respectively.