High-performance formic acid gas detection using a quartz crystal microbalance functionalized with Cdot-decorated polyvinyl acetate nanofibers

Formic acid is an organic compound that can be harmful and toxic to human health. Thus, accurate detection of its concentration in the air is crucial. Therefore, this study aims to develop a formic acid gas sensor based on a quartz crystal microbalance (QCM) with an active layer of polyvinyl acetate (PVAc) nanofibers and carbon dots (Cdots). Tests using the sensor show that the addition of Cdots significantly improves its performance. The sensitivity of the sensor with a PVAc nanofiber active layer was 0.126 Hz ppm−1, while after the addition of Cdots, the sensor's sensitivity could reach 2.552 Hz ppm−1, an increase of 20 times. The fabricated sensor also has high selectivity toward formic acid compared to other analytes. Additionally, the response and recovery times of the sensor were found to be 27 and 63 seconds, respectively. Also, the fabricated sensors show high stability under 29 days of testing. Therefore, the fabricated QCM-based sensor using Cdots as an active layer could be a promising candidate for the development of an effective and sensitive formic acid gas sensor.