Preparation of porous tin dioxide powder by ultrasonic spray pyrolysis and their application to sensor materials

Porous SnO2 powders have been prepared by pyrolysis of atomized aqueous SnCl2 or SnCl4 precursor solutions containing polymethylmethacrylate (PMMA) microspheres. The diameter of macropores existing in the porous SnO2 powders (about 400–800 nm in diameter) was about 150–200 nm. In addition, the wall thickness of the porous SnO2 powder prepared from SnCl2 was presumed to be thinner than that prepared from SnCl4. A SnO2 sensor fabricated from the powder prepared by pyrolysis of the aqueous SnCl2 solution at 1100 °C showed the highest response to 1000 ppm H2 in air among the sensors tested.