An Ultrasensitive QCM Humidity Sensor Based on GO/OH-GQDs

Sensitivity is one of the most important characteristics of quartz crystal microbalance (QCM) humidity sensors, and the methods to improve the sensitivity have always been the research focus in the field of QCM humidity sensors. This study proposes an ultrasensitive (179.88 Hz/%RH) QCM humidity sensor using graphene oxide (GO) and hydroxylated graphene quantum dots (OH-GQDs) as the sensitive materials. The experimental results show that the incorporation of OH-GQDs significantly increases the number of active sites on the GO, and the GO/OH-GQDs composite has a larger specific surface area, which greatly increases the water absorption capacity. In addition, the sensor has a low humidity hysteresis (1.3%), fast response and recovery times (7/10 s), good stability, and good repeatability. This sensor's ultrahigh sensitivity suggests significant potential for advancing the development of high-performance QCM humidity sensors.