Ultrasensitive and highly selective detection of methoxy propanol based on Ag-decorated SnO2 hollow nanospheres

Ag-decorated SnO2 hollow spheres with different mass ratios were synthesized through a two-step synthesis route. The morphology of as-prepared materials was characterized via FESEM and TEM microscopes, and the results proved the rough and porous spherical structures. The EDX and XPS patterns verified the elementary composition, especially for Ag/SnO2, the standard peaks of Ag were obviously observed. The N2 isotherm of SnO2 hollow spheres belongs to a type-IV isotherm with a large type H3 hysteresis loop. The pore size distribution covered a range of 35-80 nm and the sample showed a high BET surface area of 31.91 m2/g. During the systematic examinations of gas sensing performance, 5 wt% Ag/SnO2 showed superior properties, including the ultrahigh response of over one hundred to methoxy propanol within a wide concentration range and the excellent selectivity for detecting methoxy propanol among other gases. Moreover, the synthesis mechanism and gas sensing mechanism were discussed, which indicated that both the morphology of SnO2 hollow spheres and the catalytic effect of Ag nanoparticles played important roles on the gas sensing properties, and could be used for the further design of gas sensor utilizing other oxide semiconductors.