Room temperature CO sensing of selectively grown networked ZnO nanowires by Pd nanodot functionalization

Room temperature sub-ppm CO sensing was realized in selectively grown networked ZnO nanowires by functionalizing their surfaces with Pd nanodots. In particular, the γ-ray radiolysis was applied to the Pd nanodot functionalization. The CO sensing characteristics of the Pd-functionalized ZnO nanowires were compared with those of bare ZnO nanowires. The Pd functionalization sharply improved the resistance responses at CO concentrations in the range of 100 ppb–2 ppm. At room temperature, the Pd-functionalized ZnO nanowire sensors exhibited a response of 1.02 at as low as 100 ppb CO. The improvement of sensing capability by the Pd nanodot functionalization seems to be associated with the combined effect of electronic and chemical sensitizations due to the Pd nanoparticles.