Tin dioxide nanoparticles with high sensitivity and selectivity for gas sensors at sub-ppm level of hydrogen gas detection

A wet chemical method was employed to prepare Au-loaded sensor using tin dioxide (SnO₂) nanoparticles (NPs) which has excellent hydrogen (H₂) gas sensing properties. The structural, compositional, morphological, and electrochemical properties of these materials are characterized by X-ray diffraction, field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy and electrochemical workstation, respectively. The results show that the response time of Au-loaded sensor based on SnO₂ NPs to 100 ppm H₂ is 26 s at 350 °C, which is much shorter than that of the pristine SnO₂ sensor. Meanwhile, the effect of operating temperature and Au loading on ‘n’ value (factor for evaluating sensitivity response) is studied and the results demonstrated that the Au-loaded sensor based on SnO₂ NPs can detect H₂ gas down to 0.4 ppm. Moreover, the Au-loaded sensor based on SnO₂ NPs with an excellent selectivity to H₂ gas against carbon monoxide, methane, and sulfur dioxide is illustrated in this paper, which indicates that the Au-loaded sensor using SnO₂ NPs is a good candidate for practical H₂ sensors and other industrial applications. Statistical analysis was performed on the FESEM images of sensors based on SnO₂ NPs and 0.5 atomic (at)% Au-loaded SnO₂ NPs. Roughness parameters were evaluated and a correlation was established between the morphology, topography and chemical composition of the samples.