(110)-Oriented ZIF-8 Thin Films on ITO with Controllable Thickness

(110)-oriented zeolitic imidazolate framework (ZIF)-8 thin films with controllable thickness are successfully deposited on indium tin oxide (ITO) electrodes at room temperature. The method applied uses 3-aminopropyltriethoxysilane (APTES) in the form of self-assembled monolayers (SAMs), followed by a subsequent adoption of the layer-by-layer (LBL) method. The crystallographic preferential orientation (CPO) index shows that the ZIF-8 thin films are (110)-oriented. A possible mechanism for the growth of the (110)-oriented ZIF-8 thin films on 3-aminopropyltriethoxysilane modified ITO is proposed. The observed cross-sectional scanning electron microscopy (SEM) images and photoluminescent (PL) spectra of the ZIF-8 thin films indicate that the thickness of the ZIF-8 layers is proportional to the number of growth cycles. The extension of such a SAM method for the fabrication of ZIF-8 thin films as described herein should be applicable in other ZIF materials, and the as-prepared ZIF-8 thin films on ITO may be explored for photoelectrochemical applications.