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

We have developed a tungsten disulfide (WS)/multiwall carbon nanotubes (MWCNTs) nanocomposite based QCM gas sensor for (trimethylamine) TMA gas sensing of low concentrations. WS/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 WS/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 WS and MWCNTs-1 based QCM sensor. The response time of WS/MWCNTs based QCM sensor was 294.1 and 142.9 s shorter than WS and MWCNTs-1 for 500 ppb TMA gas. And the response of the WS/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 WS 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) WS materials, density functional theory (DFT) calculations based on first-principle were conducted in the Vienna Ab-initio Simulation Package under ideal conditions.