Controllable Low-Temperature Hydrothermal Synthesis and Gas-Sensing Investigation of Crystalline SnO₂ Nanoparticles

SnO₂ nanoparticles have been successfully synthesized by a facile hydrothermal method from SnCl₂·2H₂O, hexamethylenetetramine, and trisodium citrate in water at 120 °C for 12 h. The effects of surfactant and precipitant on SnO₂ synthesis were investigated. SnO₂ nanoparticles can be synthesized in the temperature range of 120-180 °C with long reaction time in the presence of trisodium citrate. When NaOH was used as precipitant instead of hexamethylenetetramine, it is difficult to obtain SnO₂ nanoparticles at 120 °C in the presence of trisodium citrate. SnO₂ nanoparticles with an average size of about 5 nm show good crystallinity and excellent sensitivity to ethanol and acetaldehyde in about 55% relative humidity.