Detection of Volatile Organic Compounds Using MOF and Metal Oxide Coated QCM Sensors

Abstract

Developing sensitive and selective gas sensors is crucial for environmental monitoring and industrial safety applications. In this study, quartz crystal microbalance (QCM)-based sensors were fabricated by coating their surfaces with different sensing layers, including Gd-MOF, La-MOF, ZnO, and P25. The initial resonance frequencies of the coated sensors were around 9.94 MHz, and the deposited mass loadings ranged from 8.17 to 27.90 ng/c  depending on the material, as determined from the Sauerbrey equation. Distinct frequency response patterns were observed depending on both the sensing material and the analyte gas. The sensing performance of the fabricated sensors was evaluated toward ethanol, chlorobenzene, n-heptane, and toluene gases within the concentration range of 1000–5000 ppm. The sensors were tested under stable temperature and flow conditions using a gas mixing system, and their frequency–time responses were recorded. When different coating materials were compared, it was observed that sensors coated with P25 and La-MOF exhibited notably higher sensitivity toward aromatic gases. These findings reveal that the choice of coating material directly influences the VOC detection performance of QCM-based sensors.