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 °C, whereas an improved response to C₃H₇OH was observed at 150 °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.