Co-Doped Branched ZnO Nanowires for Ultraselective and Sensitive Detection of Xylene

• Published in: ACS applied materials & interfaces Vol. 6; no. 24; pp. 22553 - 22560
• Main Authors: Woo, Hyung-Sik, Kwak, Chang-Hoon, Chung, Jae-Ho, Lee, Jong-Heun
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 24.12.2014
• Subjects: selectivity; xylene; gas sensor; ZnO nanowires; Co-doping
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/am506674u

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.