Multi-walled carbon nanotube arrays for gas sensing applications

Suresh Rajaputra, Raghu Mangu, Patricia Clore, Dali Qian, Rodney Andrews, Vijay P. Singh

Research output: Contribution to journalArticlepeer-review

41 Scopus citations

Abstract

Vertically aligned multi-walled carbon nanotube (MWCNT) arrays fabricated by xylene pyrolysis in anodized aluminum oxide (AAO) templates without the use of a catalyst were integrated into a resistive sensor design. Steady state sensitivities as high as 5% and 10% for 100 ppm of NH3 and NO 2, respectively, at a flow rate of 750 sccm were observed. A thin layer of amorphous carbon (5-50 nm), formed on both sides of the template during xylene pyrolysis, was part of the sensor design. The thickness of the conducting amorphous carbon layers was found to play a crucial role in determining the sensitivity of the resistive sensor. A study was undertaken to elucidate (i) the dependence of sensitivity on the thickness of amorphous carbon layers, (ii) the effect of UV light on gas desorption characteristics and (iii) the dependence of room temperature sensitivity on different NH3 flow rates. Variations in sensor resistance with exposure to oxidizing and reducing gases are explained on the basis of charge transfer between the analytes and the CNTs which were modeled as p-type semiconductors.

Original languageEnglish
Article number345502
JournalNanotechnology
Volume19
Issue number34
DOIs
StatePublished - Aug 27 2008

ASJC Scopus subject areas

  • Bioengineering
  • General Chemistry
  • General Materials Science
  • Mechanics of Materials
  • Mechanical Engineering
  • Electrical and Electronic Engineering

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