Humidity-Mediated QCM Sensor Based on COF-5 for Carbon Dioxide Detection

In this work, covalent organic frameworks (COF-5) are synthesized based on the dehydration reaction of organic ligands and serve as the sensitive layers to realize the reliable detection of CO
₂
. The as-prepared COF-5 based quartz crystal microbalance (QCM) sensor shows a humidity-enhanced CO
₂
response. Under 80% RH, the response to 8000 ppm CO
₂
is 154 Hz at room temperature. In addition, the sensor also shows the great selectivity and repeatability. The large specific surface area and -OH group of COF-5 provide the great platform for the adsorption/desorption of CO
₂
molecules on the sensitive membrane surface. This work paves the way for rational design of QCM CO
₂
sensors with the high performances.