Biomimetic synthesis of zeolitic imidazolate frameworks and their application in high performance acetone gas sensors

A series of zeolitic imidazolate frameworks (ZIFs) were synthesized by a facile and environmental friendly biomimetic method. The textural properties of the ZIFs were characterized by PXRD, FESEM, TEM and FT-IR spectra. These results showed ZIF 90 having typical rhombic dodecahedron crystals with a diameter of 800-1200 nm. Furthermore, the presence of rich aldehyde groups is confirmed through chemical analysis. Gas-sensing tests of quartz crystal microbalance (QCM) transducers based on ZIFs were investigated. The results showed that ZIF-90 based sensors exhibited excellent sensing performance towards low concentration of acetone vapor, such as high sensitivity (the frequency shift was 95 Hz @ 1 ppm), fast response (the response/recovery time was 12 s/17 s, respectively) and good selectivity. On the basis of temperature-varying experimental method, a moderate adsorption enthalpy (the value of Delta H-theta was -57.93 kJ/mol) was obtained, indicating the existence of weak and reversible chemisorption between ZIF-90 and acetone molecules. The value of adsorption enthalpy (Delta H = - 60.10 kJ/mol) obtained from Density functional theory is in close agreement with the ex- perimental results.