Understanding theGrowth of ZIF‑8 Thin Filmand Its Room Temperature Carbon Dioxide Sensing via Quartz CrystalMicrobalance

Metal–organic frameworks (MOFs), particularly zeolitic imidazolate frameworks (ZIFs), have emerged as promising materials for gas sensing applications due to their high surface area and tunable porosity. This study presents a systematic chemical bath deposition (CBD) approach for fabricating ZIF-8 films with precisely controlled thicknesses of up to 2.5 μm on functionalized surfaces. Film particle evolution and growth mechanisms were investigated by using scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and time-of-flight secondary ion mass spectrometry (ToF-SIMS) combined with in situ growth monitoring. Imidazolate achieved a uniform growth rate of 95 nm per cycle, and imidazolate-surface interfacial coordination was elucidated. By integrating these controllable ZIF-8 films with a quartz crystal microbalance (QCM), we developed a gravimetric gas sensor that demonstrated enhanced CO₂ adsorption capacity with increasing film thickness and achieved a detection limit of 0.5%. This systematic approach to controlling the ZIF-8 film thickness enables precise quantification of gas absorption, advancing the development of high-precision gas sensors for environmental monitoring applications.