Ultrasensitive Room Temperature Formaldehyde Sensors Based on F Doped ZnO Nanostructures Activated by UV Light

It is urgent to develop an ultrasensitive formaldehyde (HCHO) sensor that can operate at room temperature and has a low detection limit. Metal oxide semiconductors are excellent gas sensitive materials. Therefore, in this paper, we present the synthesis of fluorine (F) doped zinc oxide (ZnO) porous nanomaterials through a straightforward one-pot method with the optimization of F doping levels to achieve the detection of low concentrations of HCHO under UV light at room temperature. Under 375 nm UV light, the sensor exhibits a response value of 386% to 10 ppm of HCHO, which is 2.6 times higher than that of pure ZnO, and its detection limit is as low as 75 ppb. It has excellent selectivity, stability, and moisture resistance, which can meet the requirements of HCHO detection in daily life. Analysis reveals that doping ZnO with F not only increases the material's specific surface area but also introduces active sites. Furthermore, it alters the state of HCHO on the material's surface from physical adsorption to chemical adsorption. The above reasons together enhance the adsorption of HCHO on the gas sensitive material, thereby improving its gas sensitivity performance. Overall, this work demonstrates that F-doped ZnO is a potential material for ultrasensitive HCHO sensors and provides insights into the interpretation of the effect of doping on the gas sensitivity properties of materials.