Sensing performance and DFT investigation of methylamine gas detection using SnO₂-decorated PEO nanofiber-coated quartz crystal microbalance

Excessive exposure to methylamine gas can have negative effects on human health. Therefore, a new, low-cost, portable, and real-time method for detecting methylamine gas is urgently needed. This study developed a quartz crystal microbalance (QCM)-based methylamine gas sensor with a polyethylene oxide (PEO) and SnO2 active layer. We used a combination of electrospinning and dropcasting to coat the QCM surface. Adding SnO2 significantly improved the sensor’s performance. The fabricated sensor has a sensitivity of 0.323 Hz·ppm−1, which is much higher than that of the sensor without SnO2. The fabricated sensor also showed a low detection limit, good repeatability and reversibility, and rapid response and recovery times. In addition, the sensor showed reasonable stability. Moreover, the sensor showed exceptional selectivity towards other gas analytes, including alcohol, benzene, toluene, xylene, and acetone. Lewis acid–base interactions are believed to be the main sensing mechanism between SnO2 and the gas analyte molecules. In addition, density functional theory (DFT) analysis is used to assess agreement between experiments and simulations and to support the proposed sensing mechanisms. Overall, the performance test demonstrates that the fabricated sensor can be an excellent alternative for detecting methylamine gas.