Pierrick Clément

Pt- and Pd-decorated MWCNTs for vapour and gas detection at room temperature

Summary Here we report on the gas sensing properties of multiwalled carbon nanotubes decorated with sputtered Pt or Pd nanoparticles. Sputtering allows for an oxygen plasma treatment that removes amorphous carbon from the surface of the carbon nanotubes and creates oxygenated surface defects in which metal nanoparticles nucleate within a few minutes. The decoration with the 2 nm Pt or the 3 nm Pd nanoparticles is very homogeneous. This procedure is performed at the device level (i.e., for carbon nanotubes deposited onto sensor substrates) for many devices in one batch, which illustrates the scalability for the mass production of affordable nanosensors. The response to selected aromatic and non-aromatic volatile organic compounds, as well as pollutant gases has been studied. Pt- and Pd-decorated multiwalled carbon nanotubes show a fully reversible response to the non-aromatic volatile organic compounds tested when operated at room temperature. In contrast, these nanomaterials were not responsive to the aromatic compounds studied (measured at concentrations up to 50 ppm). Therefore, these sensors could be useful in a small, battery-operated alarm detector, for example, which is able to discriminate aromatic from non-aromatic volatile organic compounds in ambient.

Functionalised multi-walled carbon nanotubes for chemical vapour detection

Oxygen plasma functionalised Multi–Walled Carbon Nanotubes (MWCNT) were used to prepare gas sensors that can operate at room temperature. Alumina substrates with interdigitated gold electrodes were employed as transducers and the air–brushing method was used to coat them with carbon nanotube film. Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM) images of deposited MWCNT were obtained. The sensing properties in the presence of acetone and ethanol vapours were measured by impedance spectroscopy. The resistance variation of the prepared MWCNT films increases with the concentration of the vapours. Limits of detection of 1.76 ppm and 4.03 ppm for ethanol and acetone were obtained, respectively, with good reproducibility.

Nitrogen Dioxide Wireless Sensor Based on Carbon Nanotubes and UWB RFID Technology

This letter presents a semi-passive wireless nitrogen dioxide gas sensor based on a time-coded ultra-wideband tag. The gas is sensed by means of oxygen-plasma-treated multiwall carbon nanotubes. The reader consists of a commercial ultra-wideband radar. The signal backscattered at the tag is modulated by a single-pole double-throw switch and contains information on the gas concentration. The tag is normally in sleep mode and includes a wake-up circuit. A self-calibration circuit is also included, enabling two additional measurements used for background subtraction and calibration to be obtained. The sensor is able to detect nitrogen dioxide concentrations from 10 ppm to 100 ppm, with a mean relative error of 0.34%.

Rhodium-decorated MWCNTs for detecting organic vapours

In this paper, we describe a new approach for the development of a vapour sensor based on carbon nanotubes decorated with rhodium nanoparticles for detecting organic compounds. The morphology of treated multiwall carbon nanotubes was studied by means of high-resolution transmission electron microscopy (TEM) and the composition by X-ray photoelectron spectroscopy (XPS). Various aromatic and non-aromatic vapours were tested. For non-aromatic vapours, the response kinetics shows that these species are chemisorbed at the surface of carbon nanotubes. On the other hand, with aromatic vapours, the kinetics shows a physisorption behaviour. Also, the developed sensor shows lower sensitivity for non-aromatic than for aromatic vapours. The drift in sensor response remained below 10% after two months of sensor operation, which shows the high stability of the rhodium-carbon nanotubes film.