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

[Display omitted] •Synthesis of porous ZnO nanosheets (porosity ~ 16%, average pore size ~ 60 nm, thickness ~ 80 nm) via solvothermal method.•The improved responses were observed in porous ZnO nanosheets-based gas sensor.•Detailed explanation of the NO2 sensing mechanism. 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.