Synthesis and Characterization of Multi-Walled Carbon Nanotube/Chitosan (Mwcnt/Cs) Composite as a Sensing Layer on Quartz Crystal Microbalance (Qcm) for Detection of Volatile Organic Compounds (Vocs)

Quartz crystal microbalance (QCM) is a sensor that can detect changes in nanogram mass. QCM alone is inadequate for detecting volatile organic compounds (VOCs) as it lacks sensitivity and selectivity for a gas sensor; thus, various sensing layers were suggested to be deposited. This study introduces multi-walled carbon nanotubes (MWCNT) and chitosan (CS) composite as a potential new sensing material. MWCNT has the advantage of a large surface area, improving the adsorption of gases. At the same time, CS is a natural biopolymer with a high affinity with VOCs as it is very hydrophilic. Harnessing advantages over both materials can study the response in profiling selective VOCs. Studies were conducted through the characterization of nanocomposite using Raman spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, and Scanning Electron Microscopy (SEM) to determine the properties of the MWCNT/CS composite on QCM toward VOCs. MWCNT/CS was prepared using glutaraldehyde as a cross-linker to form a covalent bond between MWCNT and CS via sonication. CS, MWCNT, and the composite were prepared for characterization analysis. The result of FTIR spectroscopy of MWCNT/CS showed NH2, C=O, and C-N bond at 3359.45 cm-1, 2160.51-2033.71 cm-1, and 1074.25 cm-1, respectively, showing that the functional group in CS was presented in the composite. The surface morphology of the MWCNTs/CS was detected using SEM. QCM sensor with gold electrodes was fabricated by drop-casting the composite on the working electrode of the QCM. Next, an adsorption test was conducted to study the sensitivity of the composite as the sensing layer using isopropyl alcohol (IPA, 13.1 M) as VOCs. The frequency shift of the IPA adsorption for the MWCNT/CS-based sensor was 95.2 Hz with a response time of 42s. The result shows that the MWCNT/CS can be a potential sensing layer to detect VOCs.