Concomitant in Situ FTIR and Impedance Measurements To Address the 2-Methylcyclopentanone Vapor-Sensing Mechanism in MnO₂–Polymer Nanocomposites

Abstract

Polymer nanocomposite-based sensors were prepared using cellulose acetate (CA), carbon nanoparticles (CNPs), and manganese dioxide (MnO 2 ) nanorods to detect and to understand the sensing mechanism of 2-methylcyclopentanone vapor. A sensor with a mass ratio of 1:1.5:3 of MnO 2 /CNPs/CA as well as MnO 2 /CA and MnO 2 /CNP composite and MnO 2 sensors were prepared. The sensor with the three sensing materials combined exhibited an enhancement of response for 2-methylcyclopentanone vapor, ascribed to a synergistic effect between MnO 2 /CNPs/CA. An in situ Fourier-transform infrared (FTIR)-combined online LCR meter setup was used to understand the sensing mechanism of the sensor. The sensing mechanism involved a deep oxidation decomposition of the analyte to CO 2 . This was confirmed from the in situ FTIR-combined online LCR meter results, where a new distinct CO 2 bending mode IR band was recorded. To optimize the performance of the sensor, the composites were prepared by varying the amount of metal oxide added into the composites; sensor A (composition of mass ratio 1:1.5:3), sensor B (composition of mass ratio 2:1.5:3), and sensor C (composition of mass ratio 2.5:1.5:3); their compositions are MnO 2 /CNPs/CA. The performance of sensor B was higher than that of the other two sensors. The sensors also show relatively good response–recovery time. All fabricated sensors were found to have the sensing ability regenerated after the analyte was removed from the system without losing its sensing and recovery abilities. The structural and morphological features of the samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy.

Nickel Oxide-Carbon Soot-Cellulose Acetate Nanocomposite for the Detection of Mesitylene Vapour: Investigating the Sensing Mechanism Using an LCR Meter Coupled to an FTIR Spectrometer

“…The NiO-CNPs-CA had a BET surface area of 0.74 m 2 /g and a pore volume of 0.0027 cm 3 /g. The NiO-CNPs-CA material showed a decrease in BET surface area and pore size as compared to single sensing materials, which suggests that metal oxides and the cellulose polymer fill the pores that were formed between the carbon nanoparticles [ 21 , 22 ]. A decrease in BET surface area and pore size plays a crucial role in the sensitivity of the analytes during the sensing process [ 31 ].…”

“…The carbon nanoparticles (CNPs) soot was synthesized following methods reported by Olifant et al [ 22 ]. In brief, the CNPs were prepared by placing a ceramic cup above a burning candle (~1 cm above the candle) to collect the black smoke (soot).…”

“…The concentration of the injected analyte was calculated using the following formula: where C is the concentration of mesitylene at room temperature, V s is the volume injected, V is the volume size of the volumetric chamber, M r and p represent the molar mass and density of the mesitylene respectively [ 22 ].…”

“…Conducting polymers are mostly explored in gas sensors to improve sensitivity, selectivity, and to reduce the high working temperature of SMOs. However, cellulose acetate (CA) as a non-conducting polymer improves sensing performance sensitivity, selectivity, and response-recovery time [ 22 ]. In addition, the excellent characteristics from CA include nontoxicity, high surface area, high absorption capacity, inexpensive nature, and biodegradability [ 22 ].…”

“…However, cellulose acetate (CA) as a non-conducting polymer improves sensing performance sensitivity, selectivity, and response-recovery time [ 22 ]. In addition, the excellent characteristics from CA include nontoxicity, high surface area, high absorption capacity, inexpensive nature, and biodegradability [ 22 ]. Although CA has good attributes to be used in gas sensing, it is rarely reported.…”