Polythiophene/graphene/zinc tungstate nanocomposite: Synthesis, characterization, DC electrical conductivity and cigarette smoke sensing application

Abstract

Herein, we are reporting the synthesis and characterization of polythiophene (PTh) and its novel nanocomposites with zinc tungstate (ZT) and graphene/zinc tungstate (G/ZT) hybrid for Direct current (DC) electrical conductivity based cigarette smoke sensing at room temperature. X-ray diffraction, Fourier-transform infrared, Raman, scanning electron microscopy, transmission electron microscopy, ultraviolet–visible spectroscopy and thermogravimetric analysis techniques were used for the characterization of the as-prepared materials. The results showed that the DC electrical conductivity and sensing performance of PTh significantly improved by incorporation of ZT and G/ZT into it. PTh/G/ZT-3 (i.e. PTh/G/ZT nanocomposite containing 15 wt% G/ZT) was found to be the best sensor in terms of sensing response (81.5%) and reversibility (90.55%) along with the most stable semiconductor under isothermal and cyclic ageing conditions. Sensing response of PTh/G/ZT-3 was also tested in the exposure to various components of cigarette smoke (namely ammonia, carbon dioxide, ethanol, formaldehyde, acetone, benzene, toluene, phenol) and the highest sensing response was observed in the exposure to ammonia. The significant increase in conductivity of PTh/G/ZT nanocomposites was explained by the transfer of polarons from PTh to graphene, that is, creation of a hole in graphene where they achieved rapid mobility along with the extended π-conjugated system. Finally, a sensing mechanism was proposed through adsorption–desorption of cigarette smoke on the surface of PTh/G/ZT where electronic interactions between polarons of PTh and various components of cigarette smoke (mainly ammonia and ethanol) affected the change in DC electrical conductivity.

Fabrication of Reproducible and Selective Ammonia Vapor Sensor-Pellet of Polypyrrole/Cerium Oxide Nanocomposite for Prompt Detection at Room Temperature

“…Thus, the electrical conductivity can be controlled and tuned by any interaction that can change the quantity and mobility of charge carriers. Consequently, the electrical conductivity can precisely be tuned by changing both the type and level of oxidation as well as the types and amount of filler components [ 23 , 24 , 40 , 41 , 42 , 43 , 44 ]. In conducting polymer-nanocomposites, the mechanism of conductivity is described by the movement of charge carriers along with the extended π-conjugated system of polymer backbone or/and the hopping/tunnelling between fillers and polymer chains [ 23 , 43 , 48 , 49 ].…”

“…Whereas in the air, the conductivity of the sensor started to increase and became saturated ( Figure 9 ). The % sensing response of PPy and PPy/CeO 2 based sensors was evaluated by employing the formula where σ i and ∆σ correspond to the initial DC electrical conductivity and change in the conductivity of sensor-pellets in the ammonia vapor for 200 s, respectively [ 21 , 40 , 42 ].…”

“…When the sensor is detached from the vapor/gas’ atmosphere and exposed in air, the analyte molecules start to desorb, and interaction of analyte molecules with charge carriers decreases. Thus, the sensor’s electrical conductivity starts to increase with the increasing rate of desorption [ 40 , 41 , 42 , 43 , 44 , 50 , 51 ]. The sensor’s response/recovery time significantly depend on the rate of adsorption and desorption.…”

“…DC electrical conductivity and ammonia vapor sensing experiments were done by a four-in-line probe instrument attached with a PID controlled oven manufactured by Scientific Equipment, Roorkee, India. The equation used for the calculation of electrical conductivity is σ = [ln2 (2S/W)]/[2πS (V/I)] where: I, V, W, S, and σ represent the current (A), voltage (V), the thickness of the pellet (cm) probe spacing (cm) and conductivity (Scm −1 ), respectively [ 40 , 41 , 42 ].…”

The Influence of Reaction Time on Non-Covalent Functionalisation of P3HT/MWCNT Nanocomposites

“…This slightly expanded the diameter of nanotubes, which were close to the diameter of pristine MWCNT-OH, and this might explain that a longer reaction time was required to enhance the interaction between P3HT and MWCNT-OH. Such ununiform P3HT wrapped over the MWCNT-OH sidewall could be attributed to a low electronic interaction between the lone pair of sulphur ions in P3HT and the π-bond from MWCNT-OH [63], whereas nanocomposites that were prepared at 72-and 96-hour reaction times showed that the nanotubes were dispersed homogenously with less entanglement and more aligned tubes. This might be due to sufficient time for the P3HT to swell, make an interaction and wrap the MWCNT-OH sidewalls.…”