Fabrication of b-oriented MFI Film via Langmuir-Blodgett Technique

A compact and highly b-oriented MFI-type zeolite monolayer was fabricated by assembling anisotropic zeolite micro-crystals extending over the centimeter scale by Langmuir–Blodgett (LB) method. The LB monolayer was subsequently employed as a seed layer for the secondary growth of highly b-oriented and defect-free MFI zeolite films. Firstly, LB technique was used to assemble a highly b-oriented MFI type zeolite monolayer on stainless steel substrates and platinum electrodes at an optimum target pressure of 20 mN/m constantly. Secondly, the precursor pretreatment method for preparing highly b-oriented MFI films was proved to be achievable. The crystal intergrowth and orientation of the MFI films were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The experimental results confirmed that the precursor pretreatment method was an effective route to suppress the undesired a-oriented twin growth during the secondary growth step. Finally, the highly b-oriented MFI-type zeolite film modified platinum electrodes were further tested as the working electrodes in an aqueous solution including [Fe(CN)6] with a diameter of 0.72 nm. Cyclic voltammetry experimental results demonstrated that the b-oriented MFI films fabricated by the Langmuir-Blodgett method were defect-free.