Synthesis and characterizations of highly ordered KCl–MCM–41 porous nanocomposites for impedimetric humidity sensing

Mesoporous silica MCM–41 and KCl doped MCM–41 samples were prepared with varied composition of KCl 0.01wt/wt%−1.0wt/wt% by chemical method and pressed into circular discs followed by heat-treatment process. The samples were characterized by Fourier Transform Infrared Spectroscopy, X-ray powder diffraction, Scanning electron microscopy, Transmission electron microscopy and Brunauer–Emmett–Teller analysis. 0.5wt/wt% KCl–MCM–41 shows the best humidity sensing in circular discs. The discs show four orders of magnitude change in impedance from undoped to doped 0.5wt/wt% KCl–MCM–41 (sample K7) with the response time and the recovery time being 30 and 45 s, respectively. Small humidity hysteresis and good stability results suggest the 0.5wt/wt% KCl–MCM–41 is a good candidate in fabricating humidity sensors with high performance and better stability. The sample K7 is shown to exhibit excellent linearity in the whole humidity range of 11–95%RH. It also shows satisfactory reversibility and fast response to the environmental moisture.