Improving humidity sensor performance through phenylphosphonic acid-intercalated layered double hydroxide

This work delineates the development of humidity sensors utilizing layered double hydroxides (LDH) intercalated with phenylphosphonic acid (PPA), characterized by strong coordination and hydrophilicity. Following the meticulous synthesis of pristine LDH and PPA-LDH, sensor fabrication and comprehensive performance evaluation were conducted. Morphological analysis through SEM and TEM revealed a layered, thin PPA-LDH structure, augmenting the surface area for interaction with water. Density functional theory (DFT) computations elucidated the enhanced sensing mechanism, demonstrating that PPA intercalation significantly amplifies the adsorption energy of water molecules at metal sites, thereby facilitating proton and charge transfer. At 85 % relative humidity, the PPA-LDH sensor manifested an astonishing response of 4392.3 %, showcasing exceptional cyclic stability and rapid response/recovery times of 23 and 10 s, respectively. Comparative analysis with existing technologies underscored the superior sensitivity and response characteristics of the PPA-LDH sensor. The study concludes that PPA-intercalated LDH notably enhances humidity sensing capabilities, furnishing a material with heightened sensitivity and stability for the forthcoming generation of humidity sensors.