Gas sensing properties of MWCNT layers electrochemically decorated with Au and Pd nanoparticles

Abstract

Multiwalled carbon nanotube (MWCNT)-based chemiresistors were electrochemically decorated with Au and Pd nanoparticles (NPs), resulting in an improvement in the detection of gaseous pollutants as compared to sensors based on pristine MWCNTs. Electrophoresis was used to decorate MWCNTs with preformed Au or Pd NPs, thus preserving their nanometer-sized dimensions and allowing the metal content to be tuned by simply varying the deposition time. The sensing response of unmodified and metal-decorated MWCNTs was evaluated towards different gaseous pollutants (e.g., NO2, H2S, NH3 and C4H10) at a wide range of concentrations in the operating temperature range of 45–200 °C. The gas sensing results were related to the presence, type and loading of metal NPs used in the MWCNT functionalization. Compared to pristine MWCNTs, metal-decorated MWCNTs revealed a higher gas sensitivity, a faster response, a better stability, reversibility and repeatability, and a low detection limit, where all of these sensing properties were controlled by the type and loading of the deposited metal catalytic NPs. Specifically, in the NO2 gas sensing experiments, MWCNTs decorated with the lowest Au content revealed the highest sensitivity at 150 °C, while MWCNTs with the highest Pd loading showed the highest sensitivity when operated at 100 °C. Finally, considering the reported gas sensing results, sensing mechanisms have been proposed, correlating the chemical composition and gas sensing responses.

Characterization of Flexible Multi-Walled Carbon Nanotubes Network Sensor to Freon Gas Detection

“…Table1-XRD patterns of the MWCNTs -OH network before and after exposure to Freon. Sensor characterization was carried out using a home-made system, described in Figure -3, and calculated using the common sensor sensitivity S given by equation ( 1) [17,18]:…”

“…The results revealed that the sensor sensitivity is better in low concentrations, where it can sense the environment pollution with Freon gas in the same efficiency, while being not affected by the amount of ambient air. To estimate Freon gas concentrations at the level of one-millionth of a million as a function of operating temperature, equations ( 2) and ( 3) [18] were used.…”

Improving Gas-Sensing Performance Based on MOS Nanomaterials: A Review

“…With the development of advanced manufacturing technology and new materials, high-performance gas sensors based on different principles and structures have been widely developed [ 8 , 9 ]. Multiwalled carbon nanotubes and a graphene gas sensor have been successfully developed and manufactured by Dilonardo et al [ 10 ] and Hayasaka et al [ 11 ]. However, traditional nanomaterials sensitize the adsorption of toxic gases, accompanied by a decline in performance and the generation of by-products.…”

Wet chemistry route for the decoration of carbon nanotubes with iron oxide nanoparticles for gas sensing

“…Among the wide range of functionalization strategies that can be envisaged for tailoring the selectivity of CNTs towards target gases, one of the simplest consists of decorating the outer wall of CNTs with metal or metal oxide nanoparticles [6–9]. In some cases, metal or metal oxide nanoparticles show interesting catalytic properties for the decomposition of target molecules into more reactive species that, in turn, interact with CNTs.…”