Selective, sensitive, and stable NO₂ gas sensor based on porous ZnO nanosheets

In this study, we synthesized porous (porosity: ~16%, average pore size: ~60 nm) ZnO nanosheets (thickness: ~80 nm) using a conventional solvothermal method to investigate NO₂ gas sensing properties. Porous ZnO nanosheets triggered the detection of NO₂ gas with high sensitivity. Responses of 2.93 – 0.5 ppm and 74.68 – 10 ppm NO₂ gas at 200 °C were observed in the porous ZnO nanosheet-based gas sensor. In addition, improved sensing properties with high selectivity to NO₂ gas, reasonable stability, and high response even in the presence of water vapor molecules were obtained. We found that the enhanced NO₂ gas response of the porous ZnO nanosheet-based gas sensor was due to the synergetic effects of the high surface area, ZnO/ZnO homojunctions, and structural defects. We developed a highly sensitive NO₂ gas sensor with improved reliability using morphologically engineered ZnO, which was prepared via a simple and scalable chemical-synthesis route.