Journal of Sensors 
Volume 2008 (2008), Article ID 107057, 8 pages
doi:10.1155/2008/107057
Research Article

Surface Modification of Carbon Nanotube Networked Films with Au Nanoclusters for Enhanced NO2 Gas Sensing Applications

M. Penza,1 R. Rossi,1 M. Alvisi,1 G. Cassano,1 M. A. Signore,1 E. Serra,2 and R. Giorgi2

 1Department of Physical Technologies and New Materials, ENEA, C.R. Brindisi, P.O. Box 51 Br-4, 72100 Brindisi, Italy
2Department of Physical Technologies and New Materials, ENEA, C.R. Casaccia, P.O. Box 2400, 00100 Rome, Italy
Received 30 May 2008; Accepted 22 September 2008

Recommended by Kourosh Kalantar-Zadeh

Abstract

Multiwalled carbon nanotube (MWCNT) films have been deposited by using plasma-enhanced chemical vapor deposition (PECVD) system onto alumina substrates, provided with 6 nm thick cobalt (Co) growth catalyst for remarkably improved NO2 gas sensing, at working temperature in the range of 100–250∘C. Functionalization of the MWCNTs with nanoclusters of gold (Au) sputtering has been performed to modify the surface of carbon nanotube networked films for enhanced and specific NO2 gas detection up to sub-ppm level. It is demonstrated that the NO2 gas sensitivity of the MWCNT-based sensors depends on Au-loading used as surface-catalyst. The gas response of MWCNT-based chemiresistor is attributed to p-type conductivity in the Au-modified semiconducting MWCNTs with a very good short-term repeatability and faster recovery. The sensor temperature of maximum NO2 sensitivity of the Au-functionalized MWCNTs is found to decrease with increasing Au-loading on their surface, and continuous gas monitoring at ppb level of NO2 is effectively performed with Au-modified MWCNT chemiresistors.