One-step synthesis of hierarchical Ni-Fe-Al layered double hydroxide with excellent sensing properties for NOx at room temperature

In this paper, hierarchical flower-like Ni-Al-layered double hydroxide (NA-LDH) and Ni-Fe-Al-layered double hydroxide (NFA-LDH) intercalation compounds were synthesized by a facile one-step hydrothermal method using sodium dodecyl sulfate (SDS) as the intercalation layer and template. The NFA-LDHs with a Ni : Fe : Al molar ratio of 1 : 1 : 1 (NFA 1-1), which have porous hierarchical nanostructures and channels between the layers, provided the channels with fast carrier transportation and gas adsorption-desorption. Therefore, NFA 1-1 showed good sensing properties at 100 ppb for the detection of NOx at room temperature, and the response toward 100 ppm NOx was 82%, which was 2.3 times higher than that of pure NA-LDHs at room temperature. NFA-LDHs might be promising compounds for high performance gas sensing for commercial application. The enhanced gas sensing of NFA 1-1 can be ascribed to the unique hierarchical porous structure and the highly oriented layered single crystal structure and composition, which can enhance conductivity/carrier densities, fast carrier transportation and gas adsorption-desorption, and provide a large number of active sites for surface contact reactions.