Rapid and highly sensitive detection of formaldehyde at room temperature using rGO/WO3 nanocomposite

Formaldehyde (HCHO) is an indoor toxic volatile compound (VOC) gas, which can harm respiratory tract of human beings when a person is exposed to low concentration of HCHO for a long time. In this study, an HCHO sensor with high response and low detection limit based on rGO/WO3 (rGW) nanocomposite was successfully synthesized by hydrothermal method. Experimental results depict that the average response value of rGW is about 2000 towards 500 ppm HCHO at room temperature, the response/recovery time is 2.8 s/1.7 s for HCHO at 500 ppb and the low detection limit is 500 ppb. Moreover, rGW exhibits excellent selectivity and good stability. Compared to WO3, the combination of rGO with WO(3 )can increase the oxygen vacancy on WO3 surface and afford more active sites for capturing HCHO. Furthermore, the formation of electron depletion layer and potential energy barrier between rGO and WO3 increase intrinsic impedance of rGW nanocomposite to further enhance the property of HCHO sensor based on rGW. This study indicates that the combination of rGO with WO3 can efficiently enhance the property of WO3-based HCHO sensor at room temperature, which is conducive to the application of metal oxide semiconductor in field of gas sensors.