Issue 19, 2012
From the journal:

Nanoscale

Ag nanocrystal as a promoter for carbon nanotube-based room-temperature gas sensors†

Shumao Cui,‡a   Haihui Pu,‡a   Eric C. Mattson,b   Ganhua Lu,a   Shun Mao,a   Michael Weinert,b   Carol J. Hirschmugl,b   Marija Gajdardziska-Josifovskab  and  Junhong Chen*a  

* Corresponding authors

a Department of Mechanical Engineering, University of Wisconsin-Milwaukee, 3200 N Cramer Street, Milwaukee, WI, USA
E-mail: jhchen@uwm.edu
Fax: +1-414-229-6958
Tel: +1-414-229-2615

b Department of Physics and Laboratory for Surface Studies, University of Wisconsin-Milwaukee, 1900 E. Kenwood Blvd, Milwaukee, WI, USA

Abstract

We have investigated the room-temperature sensing enhancement of Ag nanoparticles (NPs) for multiwalled carbon nanotube (MWCNT)-based gas sensors using electrical measurements, in situ infrared (IR) microspectroscopy, and density functional theory (DFT) calculations. Multiple hybrid nanosensors with structures of MWCNTs/SnO2/Ag and MWCNTs/Ag have been synthesized using a process that combines a simple mini-arc plasma with electrostatic force directed assembly, and characterized by electron microscopy techniques. Ag NPs were found to enhance the sensing behavior through the “electronic sensitization” mechanism. In contrast to sensors based on bare MWCNTs and MWCNTs/SnO2, sensors with Ag NPs show not only higher sensitivity and faster response to NO2 but also significantly enhanced sensitivity to NH3. Our DFT calculations indicate that the increased sensitivity to NO2 is attributed to the formation of a NO3 complex with oxygen on the Ag surface accompanying a charge rearrangement and a net electron transfer from the hybrid to NO2. The significant response to NH3 is predicted to arise because NH3 is attracted to hollow sites on the oxidized Ag surface with the H atoms pointing towards Ag atoms and electron donation from H to the hybrid sensor.

Graphical abstract: Ag nanocrystal as a promoter for carbon nanotube-based room-temperature gas sensors

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Article information

DOI
https://doi.org/10.1039/C2NR31556D
Article type
Paper
Submitted
20 Jun 2012
Accepted
24 Jul 2012
First published
26 Jul 2012

Nanoscale, 2012,4, 5887-5894

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Ag nanocrystal as a promoter for carbon nanotube-based room-temperature gas sensors

S. Cui, H. Pu, E. C. Mattson, G. Lu, S. Mao, M. Weinert, C. J. Hirschmugl, M. Gajdardziska-Josifovska and J. Chen, Nanoscale, 2012, 4, 5887 DOI: 10.1039/C2NR31556D

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