MWCNT-Pt nanocomposite as the active element of harmful gas sensors

Abstract

Purpose: The goal of this paper is presentation of the variations in MWCNTs-Pt nanocomposite resistance which were examined in the presence of hydrogen with a rising concentration of, respectively, 1, 2, 3 and 4% H 2 as well as nitrogen dioxide with a rising concentration of, respectively, 20, 100, 200, 400 ppm of NO 2 . Design/methodology/approach: Variations in electrical conductivity for the MWCNTs-Pt composite placed, alternately, in the atmosphere of gas and in the atmosphere of selected gases, were measured with a measuring station equipped with precision and inert gas reducers, mass flow meters, filtration systems of gas mixture and the studied mixture's humidity and temperature control. An active layer of the transducer consisted of MWCNTs-Pt nanocomposite deposited thereon. All the measurements were carried out in the atmosphere of synthetic air (20% of O2 and 80% of N 2 ) at 22.5°C. Findings: It was found based on the results obtained that system resistance is rising as hydrogen concentration is rising in the atmospheric air. The results of analogous examinations of variations in MWCNTs-Pt nanocomposite resistance carried out for a varying concentration of nitrogen dioxide in the atmosphere of synthetic air are opposite, because lowering system resistance was noted along with a heightening concentration of NO 2 . The best results were achieved for the nanocomposite presented in the article having a 5% mass concentration of platinum and with uniformly dispersed Pt particles on the surface of carbon nanoparticles. Practical implications: The outcomes presented signify the selectiveness of the applied system consisting of carbon nanotubes decorated with platinum nanoparticles. It means that this material can be used as the active element of harmful gas sensors. Originality/value: A carbon-metal MWCNTs-Pt nanocomposite with special electrical properties was fabricated in the course of research works, whose originality is based on the appropriately selected composition and the specific morphology.

Nanocomposites Consisting of Carbon Nanotubes and Nanoparticles of Noble Metals

“…Nanocomposite materials exist consisting of carbon nanotubes together with nanoparticles of one (Au, Ag, Pt, Pd, Rh, Re, Ru, Co, Ni) [1][2][3][4][5][6] or more (Pd i Rh, Pt and Ru, Pt-Ru-Mo) [7][8][9] metals deposited on their surface, which are fabricated by various methods. Methods are employed these days of obtaining nanocomposites comprised of carbon nanotubes and rhodium and palladium nanoparticles using plasma [10], chemical reduction, [11] electrodesposition [12], electroless deposition [1], chemical and physical vapour deposition [12], electrochemical method [13,14], chemical methods with reduction of colloidal solutions [15] and methods utilising gamma irradiation [15]. The precursors of rhodium and palladium particles in different decoration processes include most frequently: colloid solutions [10], of particular metals, RhCl 3 •3H 2 O [16], 99.9% pristine rhodium [17] Rh(acac) 3 [18] and PdAc 2 [19], (NH 4 ) 2 [PdCl 4 ] [14], K 2 PdCl 4 [14], PdCl 2 [15], Na 2 PdCl 4 [20].…”

“…Methods are employed these days of obtaining nanocomposites comprised of carbon nanotubes and rhodium and palladium nanoparticles using plasma [10], chemical reduction, [11] electrodesposition [12], electroless deposition [1], chemical and physical vapour deposition [12], electrochemical method [13,14], chemical methods with reduction of colloidal solutions [15] and methods utilising gamma irradiation [15]. The precursors of rhodium and palladium particles in different decoration processes include most frequently: colloid solutions [10], of particular metals, RhCl 3 •3H 2 O [16], 99.9% pristine rhodium [17] Rh(acac) 3 [18] and PdAc 2 [19], (NH 4 ) 2 [PdCl 4 ] [14], K 2 PdCl 4 [14], PdCl 2 [15], Na 2 PdCl 4 [20]. In order to be able to apply a broad range of CNT-NPs-type nanocomposites in the modern industry, an optimum technology must be developed enabling the controlled, uniform deposition of nanoparticles of a given metal onto the surface of carbon nanotubes.…”