Temperature-dependent response to C3H7OH and C2H5OH vapors induced by deposition of Au nanoparticles on SnO2/NiO hollow sphere-based conductometric sensors

Pure SnO2, SnO2/NiO, and Au-loaded SnO2/NiO hollow spheres with different Au content were synthesized through a 1-step hydrothermal synthesis. The surface morphology and structural as well as chemical composition of the synthesized Au-loaded SnO2/NiO hollow spheres were carefully investigated. The performance of the pure SnO2, SnO2/NiO, and Au-loaded SnO2/NiO gas sensors in the detection of low concentrations of propanol (C3H7OH) and ethanol (C2H5OH) was evaluated. The as-fabricated Au (2.5 wt. %)-loaded SnO2/NiO gas sensors demonstrated enhanced gas sensing characteristics and were highly sensitive, selective, and stable to C2H5OH vapor at a low operating temperature of 75 degrees C, whereas an improved response to C3H7OH was observed at 150 degrees C. The results indicated that compared to pure SnO2 and SnO2/NiO, the Au-loaded SnO2/NiO hollow sphere-based sensor exhibited a significant improvement in the gas sensing response at a lower optimum operating temperature. The long-term stability analyses indicated that the Au (2.5 wt. %)-loaded SnO2/NiO sensor was stable even after 35 days. These findings clearly demonstrated the ability of a 2.5 wt. % Au-loaded SnO2/NiO gas sensor to detect C2H5OH and C3H7OH vapors by adjusting the operating temperature suitably.