Highly sensitive and selective ethanol sensor based on micron-sized zinc oxide porous-shell hollow spheres

Zinc oxide (ZnO) porous-shell hollow spheres (PHS) were prepared by thermally oxidizing high-purity zinc powder in an oxygen-containing atmosphere, and its ethanol gas sensing properties were measured in the concentration range of 10–400 ppm. At the optimum operating temperature of 350 °C, a sensitivity of 0.25/ppm was obtained and the response–concentration curve was of high linearity. The response and recovery times were measured to be ∼5–12 s and 8–13 s, respectively. The sensor was proved to be highly selective to ethanol. Our results indicate that ZnO PHS might be a promising material for fabricating practical ethanol sensors.