SnO2 Nanosheets for NIR-Enhanced NO2 Sensing and Adsorption/Desorption

Very recently, metal–organic framework (MOF)-based derived oxides demonstrated excellent sensing performance to NO2. However, the study on the enhancement of gas-sensing characteristics by near-infrared (NIR) light for MOF-based derived oxides is still limited. In this work, we introduced the synthesis of MOF-derived SnO2 nanosheets by solvothermal and annealing processes. The structural composition and microstructure of SnO2 nanosheets were studied by X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Brunauer–Emmett–Teller. The derived SnO2 nanosheet-based gas sensor has an extremely low theoretical detection limit to NO2 (45 ppb), ultrahigh response (1500 to 100 ppm), outstanding stability, and ideal selectivity. Furthermore, NIR illumination shortens the SnO2 sensor's NO2 adsorption/desorption process. Moreover, we also proposed that NIR-excited photoelectrons were instrumental in optimizing the NO2 gas-sensing performance of SnO2 sensors. Therefore, MOF-based SnO2 sensors are attractive for high response and rapid detection of NO2 at low operating temperatures and are expected to be widely used in the preparation of NIR-enhanced NO2 gas monitoring sensors.