Extremely sensitive ethanol sensor using Pt-doped SnO2 hollow nanospheres prepared by Kirkendall diffusion

•Pure and Pt-doped SnO2 hollow spheres were prepared by nanoscale Kirkendall diffusion.•Pure SnO2 hollow nanospheres showed high response to ppm-level ethanol.•Pt-doped SnO2 hollow spheres showed ultrahigh response and selectivity to ethanol.•Nanoscale Kirkendall diffusion can be used to prepare high performance gas sensors. The pure and 0.3wt% Pt-doped SnO2 hollow nanospheres were prepared by the oxidation of pure and Pt-doped Sn nanoscrystals embedded in carbon matrix and their gas sensing characteristics were investigated. The formation of hollow morphology was attributed to the nanoscale Kirkendall effect due to rapid outward diffusion of Sn ions and relatively slow inward diffusion of oxygen. Pure SnO2 hollow nanospheres showed a high response (resistance ratio) of 93.3 when exposed to 5ppm ethanol. The response to 5ppm ethanol was significantly increased to 1399.9 with doping 0.3wt% Pt. In addition, selectivity to ethanol was also enhanced by Pt doping. Ultrasensitive and selective detection of ethanol in pure and Pt-doped SnO2 nanospheres is explained by the effective electron depletion in hollow structures and catalytic promotion of gas sensing reaction.