Crystalline size- control of SnO2 nanoparticles with tunable properties prepared by HNO3-ethanol assisted precipitation

SnO2 nanoparticles were prepared by a novel HNO3-ethanol assisted precipitation method. The crystalline size of SnO2 nanoparticles was controlled based on aqueous solution by varying the molar ratio of HNO3 and ethanol within the range 0-0.12:0.06-0.18. The obtained SnO2 nanoparticles were characterized by TG-DSC, FTIR, XRD, TEM, HRTEM, SAED, EDS, UV-Vis, electrical resistance and bulk density measurements as a function of the contents of HNO3 and ethanol. Results indicated that the SnO2 nanoparticles with increased contents of HNO3 and ethanol featured decreased crystalline size, probably related to the increased number of nucleation sites and decreased exothermic amount at the maximum exothermic temperature about 475 °C of the SnO2 precursor. The SnO2 nanoparticles revealed bigger energy gap and larger gas response with increased HNO3-ethanol additives, which could be ascribed to the Burstein-Moss effect and more active reaction sites due to the small crystalline size. The intrinsic formation mechanism of SnO2 nanoparticles was proposed based on the formation process of SnO2 precipitate. Besides, the contents of HNO3-ethanol additives had a strong impact on the optical absorption, electrical conductivity and bulk density of SnO2 nanoparticles.