Preparation And Performance Study Of Gas Sensor Based On ZnAl-LDHs

Nitrogen dioxide(NO₂),which is produced from fuel combustion and automobile exhaust emission,is a main source resulting in air pollution;it also leads to respiratory symptoms in humans.Therefore,there is a strong market demand for NO_xsensors with high sensitivity and selectivity in air quality monitoring.Besides,the determination of fractional exhaled nitric oxide used for diagnosis of asthma further necessitates high-performance NO_xsensors with an ultra low detection range down to ppb level.Air pollution detection and indoor air detection all require high-performance gas sensors to detect and warn air quality.To develop high-performance gas sensors,the performance parameters of the gas sensor must be improved,such as sensitivity,selectivity,stability,operating temperature,response/recovery time,etc.In view of the current research and development trend of gas sensors,this paper studies the preparation of layered double hydroxide-based gas sensor,which achieves high sensitivity,fast response recovery characteristics and low detection limit.Layered double hydroxides(LDHs)have been acknowledged as potential gas sensing materials owing to their large specific surface area and compositional flexibility.In this work,highly sensitive LDHs-based nanocomposite of In(OH)₃/ZnAl In-LDHs was synthesized via hydrothermal growth of hierarchical ZnAl In-LDHs and synchronous modification of single-crystalline nanoparticles of In(OH)₃.The achieved In(OH)₃/ZnAl In-LDHs shows three-dimensional(3D)hierarchical architecture,with discrete In(OH)₃nanoparticles attachment on the nanosheet surface.The hierarchical ZnAl In-LDHs forms loose 3D sensitive skeleton facilitating easy gas diffusion;additional In(OH)₃nanoparticles modification on LDHs nanosheets induces heterojuction effect capable of further enhancement of gas-sensing response.The gas-sensing measurements reveal that the achieved In(OH)₃/ZnAl In-LDHs nanocomposite is more sensitive to NO₂with rapid dynamic characteristic in comparison to the single components.At room temperature,the In(OH)₃modified ZnAl In-LDHs can response ultra rarefied NO₂of 2.5 ppb with response of 35.4%.The significantly enhanced sensing response for the nanocomposite of In(OH)₃/ZnAl In-LDHs could attribute to the co-modulation of unique hierarchical microstructure,In-doping in LDHs layers and heterojunction effect between LDHs and the modified In(OH)₃nanoparticles.