Self-assembled SnO_2 Colloidal Particles and Their Gas Sensing Performance to H_2, C_2H_5OH and LPG

Using organo-tin Sn（OC4H9）4 as precursor, sodium dodecyl sulfonate （SDS） and SDS-gelatin （SDS-G） complex as template, two tin dioxide colloidal particles were prepared by a self-assembly method. Both SnO2 products were respectively labelled SnO2-B particles with SDS and SnO2-C particles with SDS-G, which are applied in fabricating SnO2 gas sensors corresponding to SnO2-B＇ and SnO2-C＇ sensors. X-ray diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM） and thermo-gravimetry and different thermal analysis （TG/DTA） were used for characterizations. The experimental results show that SnO2-B colloidal particles are composed of mesoporous piece-like particles, while SnO2-C particles mainly consist of spherical particles. Gas sensing measurements show that SnO2-B＇ sensor performs the best sensing response to all target gases, including H2, C2H5OH and liquid petroleum gas （LPG）. In particular, the sensing response of SnO2-B＇ sensor is achieved at 32 in H2 atmosphere at the concentration of 1000×10-6 M. The gas sensing mechanism was purposely discussed from the electron transfer process and the microstructures of the as-prepared SnO2 products. It is found that serious agglomerations in SnO2-B＇ particles facilitate the high gas sensing performance of SnO2-B＇ sensor, while mesoporous structures in SnO2-C＇ particles decrease the gas sensing response of SnO2-C＇ sensor.