Preparation of nanocrystalline stacked spherical SnO ₂ with higher specific surface area and its gas-sensing performance

Abstract Ethanol is a widely used volatile and flammable solvent, and its leakage poses serious environmental and safety risks, highlighting the need for reliable detection. Tin dioxide (SnO 2 ) is a promising material for ethanol sensing, but conventional SnO 2 sensors often suffer from low sensitivity and poor stability due to limited surface area and irregular morphology. In this study, spherical SnO 2 particles with a uniform size of 0.25 ± 0.01 μm were synthesized via a surfactant-free hydrothermal method. The particles consist of fine grains (~4 nm) and exhibit a high specific surface area of 232.20 m 2 ·g −1 , enabling abundant active sites for gas adsorption. The sensor showed excellent selectivity and fast response to ethanol, achieving a response of 48.28 at 100 ppm with a response/recovery time of 4/15 s at 300 °C, and a detectable limit down to 2 ppm. The enhanced performance is attributed to the large surface area, high porosity, and efficient gas diffusion of the spherical structure. This work provides a simple, surfactant-free strategy for fabricating high-performance and stable SnO 2 -based gas sensors.