title: Co-doped branched ZnO nanowires for ultraselective and sensitive detection of xylene.
abstract: Co-doped branched ZnO nanowires were prepared by multistep vapor-phase reactions for the ultraselective and sensitive detection of p-xylene. Highly crystalline ZnO NWs were transformed into CoO NWs by thermal evaporation of CoCl2 powder at 700 °C. The Co-doped ZnO branches were grown subsequently by thermal evaporation of Zn metal powder at 500 °C using CoO NWs as catalyst. The response (resistance ratio) of the Co-doped branched ZnO NW network sensor to 5 ppm p-xylene at 400 °C was 19.55, which was significantly higher than those to 5 ppm toluene, C2H5OH, and other interference gases. The sensitive and selective detection of p-xylene, particularly distinguishing among benzene, toluene, and xylene with lower cross-responses to C2H5OH, can be attributed to the tuned catalytic activity of Co components, which induces preferential dissociation of p-xylene into more active species, as well as the increase of chemiresistive variation due to the abundant formation of Schottky barriers between the branches.
authors.affiliation: Department of Materials Science and Engineering, Korea University , Seoul, 136-713, Republic of Korea.
authors.forename: Hyung-Sik
authors.initials: HS
authors.lastname: Woo
authors.forename: Chang-Hoon
authors.initials: CH
authors.lastname: Kwak
authors.forename: Jae-Ho
authors.initials: JH
authors.lastname: Chung
authors.forename: Jong-Heun
authors.initials: JH
authors.lastname: Lee
keywords: Co-doping; ZnO nanowires; gas sensor; selectivity; xylene