Hollow multi-shelled structural SnO2 with multiple spatial confinement for ethanol gas sensing

Ethanol gas sensing has been attracting more and more attention due to its significance, such as human health care, and detection in drunk driving. However, the low sensitivity, the high limit of detection and the long response time restrain its further application development. Here we report SnO2 nanomaterials with well-controlled hollow multi-shelled structure as an efficient ethanol gas sensing. The shell number was tuned by the concentration of the precursor. Among, the double-shell SnO2 nanomaterials (SnO2-D) exhibited the best selectivity towards ethanol, reaching 22.5 of Rg/Ra ratio. Moreover, the 1 ppm ethanol was even detected, the Rg/Ra ratio being 1.37. The response time to 100 ppm ethanol was only 2 s. Furthermore, the SnO2-D maintained the same performance after 21 days of continuous response to 100 ppm ethanol. Based on experiments and in situ FTIR, the outstanding sensing performance is attributed to the excellent spatial confinement and large active surface of the double-shell that combine the enhanced gas adsorption, and increase conductive electrons.