Deep Cavitand Self‐Assembled on Au NPs‐MWCNT as Highly Sensitive Benzene Sensing Interface

Abstract

Keywords: quinoxaline-walled deep cavitand, multi-walled carbon nanotubes, oxygen plasma treatment, gold nanoparticle, benzene.The unprecedented sensitivity and partial selectivity of quinoxaline-walled thioether-legged deep cavitand functionalized multiwall carbon nanotubes toward traces of benzene vapors is presented. The cavitand is grafted onto gold nanoparticle (Au-NP) decorated oxygen plasma treated multiwall carbon nanotubes (O-MWCNT) by a self-assembled monolayer process affording a product referred to as cav-Au-MWCNT. The reported technique is suitable for the mass production of hybrid nanomaterials at low cost. The cav-Au-MWCNT resistive gas sensor operates at room temperature and shows an outstanding performance toward traces of benzene vapors. The detection of 2.5 ppb of benzene in dry air is demonstrated with a limit of detection (LOD) near 600 ppt. For the first time, it is shown that a CNT nanomaterial can effectively sense the extremely harmful benzene molecule with higher sensitivity than toluene or o-xylene at the trace levels. The cavitand is well suited for binding benzene, which, being in close proximity to the MWCNT, affects its density of states (DOS) shifting the Fermi level away from the valence band. The binding of benzene is transduced in a diminution of 2 MWCNT conductance. Furthermore, the inclusion of benzene is fully reversible at room temperature, implying that the sensor can operate at very low power consumption.

Ultrasensitive room-temperature ethanol detection based on Au functionalized nanoporous SnO2/C60/SnO2 composites

“…On the other hand, several strategies demonstrated that the incorporation metal nanoparticles such as Au, Pt, Pd, and Ag to the metal oxides surface can effectively reduce the operating temperature and improve the lower limit detection, sensor response, sensitivity, and selectivity. [13][14][15][16] Au nanoparticles have received the most attention from the scientic community, especially for sensor applications, because of their chemical inertness, high adsorption, and excellent catalytic activity, [17][18][19][20] where the Au modied SnO 2 /C 60 /SnO 2 nanocomposite lm based gas sensor can be exploited to detect ethanol gas at room temperature.…”

Environmental Gas Sensing with Cavitands

“…Ballester et al. proposed a QxCav‐based sensor, whose transduction mode is conductimetric . A thioether‐legged QxCav is self‐assembled onto gold nanoparticles (Au‐NP), which in turn are grafted on multiwall carbon nanotubes (MWCNTs) previously treated with oxygen plasma (herein referred QxCav‐Au‐MWCNT, Figure a).…”

“…Ballester et al proposed aQ xCav-based sensor, whose transductionm ode is conductimetric. [49] At hioether-legged QxCav [38] is self-assembled onto gold nanoparticles (Au-NP), which in turn are grafted on multiwallc arbon nanotubes (MWCNTs) previously treated with oxygen plasma (herein referred QxCav-Au-MWCNT,F igure 4a). The interaction of the materialw ith benzene molecules in the gas phase resultsi nan electronic charge transfer process between the organic molecule and the metal-NP-CNTn anomaterial that modifies the conductive properties of the layer.T he conductimetrics ensor was exposed to different analytes vapors, like benzene, toluene, o-xylene, ethanol, and carbon monoxide.…”

Emerging and Future Possible Strategies for Enhancing 1D Inorganic Nanomaterials‐Based Electrical Sensors towards Explosives Vapors Detection

“…Combination noble metal modification with other strategies can partly realize the “one key to one lock” concept. Llobet et al demonstrated a quinoxaline‐walled thioether‐legged deep cavitand functionalized MWCNTs with unprecedented sensitivity and partial selectivity . The cavitand which acted as a specific recognizing “lock” was grafted onto AuNP decorated oxygen plasma treated MWCNT by a self‐assembled monolayer process to selective bind the “key” benzene vapor.…”