Highly mesoporous hierarchical nickel and cobalt double hydroxide composite: fabrication, characterization and ultrafast NOx gas sensors at room temperature

In this paper, highly mesoporous hierarchical nickel and cobalt double hydroxide composites (NCDHs) have been synthesized via a simple reflux method. The synthesized NCDH composites with a mass ratio of 100 : 20 for Ni(NO3)(2)center dot 6H(2)O/Co(NO3)(2)center dot 6H(2)O (NCDH-20) contained a lot of oxygen defect sites, and chemisorbed water connects the adjacent Ni(OH)(2) layers. The porous hierarchical nanostructures provide natural channels for the effective and fast transportation of carriers. Furthermore, the NCDH-20 sensor exhibits excellent gas-sensing properties, such as a low detection limit of 0.97 ppm and short response time of 0.6 s to 97 ppm NOx, due to the layered single crystal structure and unique gallery pathway. The NCDH-20 sensor with ultrafast NOx sensing has significant applications for gas sensing.