Quartz Crystal Microbalance Sensor Based onZnO-Graphene Thin Film for Gas Detection

Gas detection is vital for safety in important industrial and private sectors. Its major significance lies inits proactive risk mitigation, safeguarding lives and resources. In this paper, the focus is on the devel-opment of a gas sensor based on quartz crystal microbalance coated with a sensitive layer of zinc oxide(ZnO)-graphene nanocomposite for the detection of volatile organic compounds at room temperature.The incorporation of graphene or reduced graphene oxide is preferred in such applications due to theirexcellent electrical conductivity, chemical stability, and high surface area. These nanocomposites weresynthesized using a chemical method via spray pyrolysis. Various techniques were employed to analyzethe coated QCM electrode: contact angle measurements to assess surface wettability, Fourier transforminfrared and energy-dispersive X-ray spectroscopy to investigate the composition of the coated elec-trode, and scanning electron and atomic force microscopies were used to study its surface morphology.These analyses provided valuable insights into the nanocomposite's interaction with the environment,composition, structure, and topography of the sensor's sensitive layer. To evaluate the sensor's sensitiv-ity, the frequency shift (triangle f) of the coated QCM electrode is monitored when exposed to different gasconcentrations of ethanol, toluene, chloroform, humidity, and formamide, ranging from 47 to 142 ppm.The frequency shift indicated the detected gas concentration. The results demonstrate good repeata-bility and reversibility, which are crucial indicators of a sensor's reliability. This reliability is essen-tial for applications in environmental monitoring or industrial safety, where accurate gas detection iscritical.