Hydrothermal synthesis of ultrafine SnO2 nanospheres: effect of reaction time on physical properties

摘要

A systematic study has been done to investigate the effect of reaction time on the physical properties of hydrothermally prepared tin oxide (SnO2) nanostructures. The structural and optical properties as well as nanostructure morphology, lattice dynamics, and surface porosity of the samples were characterized by X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), FESEM, Raman, and BET analysis, respectively. The XRD of the products indicated that the nanopowders had a tetragonal polycrystalline nature with ultrafine crystallite size. The band gap energy of the compounds was determined to be 3.47 eV, demonstrating the anomalous band gap shrinkage of the SnO2 nanoparticles. Furthermore, the nature of defects, vacancy sites, and surface disorders were investigated by Raman spectroscopy, and an interesting transition was observed in the lattice vibrational modes from nanosized modes to conventional SnO2 vibrational modes. The sample prepared at the reaction time of 20 h showed the highest BET pore volume, optimal crystallinity, and the most uniform particle size.