The enhanced NO₂ sensing properties of SnO₂ nanoparticles/reduced graphene oxide composite

Multiple techniques were utilized to characterize the structure and morphology of the SnO₂/reduced graphene oxide (rGO) composite, in which the composite was prepared by a facile one-pot microwave-assisted hydrothermal method. As a result, SnO₂ nanoparticles with diameters of 3-5 nm were anchored uniformly on both sides of the rGO sheets. Meanwhile, a series of resistive-type gas sensors based on SnO₂/rGO composite and pure SnO₂ were fabricated and tested for analyzing the effects on introducing rGO. The results revealed that, the composite exhibited obviously enhanced gas sensing properties towards NO₂ with high response, fast response and recovery speed, and good selectivity and reproducibility. At 75 °C, the response of the composite to 350 ppb NO₂ was about 6.6 times of that to pure SnO₂. In addition, the response and recovery time of the sensor was greatly reduced from 39.2/54.7 to 6.5/1 min, and the detecting limit of the sensor was even as low as 50 ppb. Provided with the enlarged surface area and local p-n heterojunctions, the synergistic effect of SnO₂ nanoparticles and rGO contributed to the enhanced gas sensing properties of SnO₂/rGO composite.