Facile Synthesis of Nanocrystal Tin Oxide Hollow Microspheres by Microwave-Assisted Spray Pyrolysis Method

Tin oxide (SnO₂) hollow microspheres with narrow size distribution were prepared by a facile one-pot microwave-assisted spray pyrolysis method. The effect of temperature on microstructural and optical properties was investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), high resolution transmission electron microscope (HRTEM), and UV-Vis spectrophotometer (UV-Vis), respectively. The SnO₂ particles obtained at and above 700 °C are tetragonal rutile structure with high purity and smooth surface morphology, which consist of well-interconnected SnO₂ nanocrystallines and the shell thickness was about 26 nm. UV-Vis absorption values were quite low in visible light region and high in ultraviolet region, indicating the possible utilization for optical purpose of the as-prepared SnO₂. The band gaps were 3.88 and 4.07 eV for SnO₂ synthesized at 700 and 800 °C, respectively. As compared to traditional electrical heating or flame modes, microwave heating introduced here demonstrates a high-efficiency, environmentally benign, and time- and energy-saving technology to synthesize advanced powders.