Nanoporous Functionalized WS₂/MWCNTs Nanocomposite for Trimethylamine Detection Based on Quartz Crystal Microbalance Gas Sensor

Abstract

We have developed a tungsten disulfide (WS2)/multiwall carbon nanotubes (MWCNTs) nanocomposite based QCM gas sensor for (trimethylamine) TMA gas sensing of low concentrations. WS2/MWCNTs nanocomposite was synthesized via the hydrothermal method and was characterized for surface morphology, nanostructure, thermal stability, and elementary composition. The TMA-sensing properties of WS2/MWCNTs nanocomposite based QCM sensor were investigated. The composite based QCM sensor showed faster response time, strong response amplitude, good gas capacity, and good selectivity and stability compared with as prepared WS2 and MWCNTs-1 based QCM sensor. The response time of WS2/MWCNTs based QCM sensor was 294.1 and 142.9 s shorter than WS2 and MWCNTs-1 for 500 ppb TMA gas. And the response of the WS2/MWCNTs based QCM sensor was almost stable over 40 days, and the limit of detection (LOD) was 76 ppb calculated by the ICH method. This was ascribed to the fact that MWCNTs provided a skeleton for the growth of WS2 nanosheets and avoided agglomeration. The special structure could not only improve the structure ability but also expose more active adsorption sites. In order to further investigate the adsorption mechanism of the TMA molecule on (pure/functionalized) WS2 materials, density functional theory (DFT) calculations based on first-principle were conducted in the Vienna Ab-initio Simulation Package under ideal conditions.

Selective N,N-Dimethylformamide Vapor Sensing Using MoSe2/Multiwalled Carbon Nanotube Composites at Room Temperature

“…The presence of Se 2– was confirmed by the Se 3d 5/2 and Se 3d 3/2 peaks at 54.2 and 55.3 eV, respectively Figure d exhibits the C 1s spectrum, which could be deconvoluted into four peaks at binding energies of 282.7, 284.6, 286.3 eV, and 287.4 that correspond to the carbon in C–Mo, the graphitic carbon of the MWCNTs, and the carbon–oxygen bonds, respectively. , …”

“…However, increasing the amount of MWCNTs considerably increases the effective conductivity of the composite, masking the gas-induced change in conductivity and decreasing the relative response . Plausible reasons for the increased sensitivity of composite-based devices could be enhanced specific-surface area, the presence of defects, oxygen vacancies, and synergistic effects that come into play after a composite is formed. ,,, Hence, all sensing measurements were carried out using only the MoSe 2 /MWCNTs-10 mg sample. A good chemiresistive sensor should ideally possess a greater response at low analyte concentrations and room temperature.…”

“…The increased BET surface area, more active sites, mesoporous nature, and small average pore size may facilitate the diffusion, penetration, and adsorption of DMF molecules, making MoSe 2 /MWCNTs-composite-based sensors significantly better in comparison to bare MoSe 2 . Also, the DMF molecule is a hard Lewis base and has a high donor strength toward a series of acids, in comparison to other Lewis bases. , MoSe 2 behaved like a p-type semiconductor with a direct band gap, whereas MWCNTs have an extremely narrow band gap. ,, On the basis of DFT simulations, Raman spectra, and sensing transients with DMF, the following plausible explanation can be made about the sensing process. Both MoSe 2 and MWCNTs behave like p-type materials, and a schematic energy band diagram is drawn in Figure S10a.…”

“…Further, CNTs have a significant specific surface area, a hollow structure, and unique electrical properties, making them an attractive one-dimensional nanomaterial for sensors, especially for gas detection. Previous reports have shown that modifying the semiconducting characteristics of TMDCs through the decoration of carbon nanotubes can achieve the desired sensitivity and selectivity for VOC detection. − …”

Room-temperature triethylamine sensing of a chemiresistive sensor based on Sm-doped SnS2/ZnS hierarchical microspheres

“…13,14 The efficient charge transport between the N atom of a gas molecule and the S atom of LMDs enabled gas sensing of amine and nitro compounds. 15,16 SnS 2 has attracted intense attention from gas sensing sectors by virtue of its excellent semiconducting properties, including high electronegativity, large gas molecule adsorption capability with fascinating surface kinetics, tunable band structure, high mobility of charge carriers, non-toxicity and stability. [17][18][19] In recent years, a variety of routes have been employed to design high performance sensing materials to particular analytes, including controlling the grain size, 20 engineering the surface structure, 21 and generating nanocomposites with multiproperties.…”