Carbon nanotube (CNT) networked films have been grown by radiofrequency plasma enhanced chemical vapour deposition (RF-PECVD) technology onto low-cost alumina substrates, coated by nanosized Fe-catalyst for growing CNTs, to perform chemical detection of hazardous gases, at an operating sensor temperature in the range 25-150 °C. The morphology and structure of the CNT networks have been characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy. The carbon nanotubes were "forest-like" with ropes vertically-aligned to the substrate surface. A dense network of bundles of multiple tubes consisting of multi-walled carbon nanostructures appears with a maximum length of 7-10 μm and single-tube diameter varying in the range of 5-35 nm. Surface functionalizations of the vertically-aligned CNT networks with nominally 5 nm thick Pt-, Ru- and Ag-nanoclusters, prepared by magnetron sputtering, provide higher sensitivity for significantly enhanced gas detection of NO2, H2, ethanol and toluene up to a low limit of sub-ppm level. The measured electrical conductance of the functionalized CNTs upon exposures of a given oxidizing and reducing gas is modulated by a charge transfer model with p-type semiconducting characteristics. Functionalized CNT gas sensors exhibited better performances compared to unmodified CNTs, making them highly promising candidates for environmental air monitoring applications, at ppb-level of toxic gas detection. © 2009 Elsevier B.V. All rights reserved.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Materials Chemistry
- Metals and Alloys
- Surfaces, Coatings and Films
- Surfaces and Interfaces
Penza, M., Rossi, R., Alvisi, M., Signore, M. A., Cassano, G., Dimaio, D., Pentassuglia, R., Piscopiello, E., Serra, E., & Falconieri, M. (2009). Characterization of metal-modified and vertically-aligned carbon nanotube films for functionally enhanced gas sensor applications. Thin Solid Films, 517(22), 6211 - 6216. https://doi.org/10.1016/j.tsf.2009.04.009