Preparation Of Metal-Organic Framework Thin Film With Electrochemical Molecular Selectivity

In recent years, the MOF materials with the large specific surface area, uniform but tunable cavities and tailorable chemistry is widely payed more attention, they show the great application potentials in gas separation and storage, chemical sensing, catalysis and drug delivery etc.. However, the reported research on MOF materials for electrochemical applications is relatively rare and the MOF film integrated into the electrode surface for electrochemical molecular selective catalysis and sensing is an important direction in this area. In this paper, we chosen relatively stable ZIF-8 and UiO-66 reported as the research objects, and explored the possibility of MOFs in electrochemical molecular selective catalysis and sensing applications. The related research mainly from the following three aspects:(1) At room temperature, the compact, smooth and no defect ZIF-8 film was obtained successfully on FTO using alcohol phase synthesis method. The morphology and structure of ZIF-8 film was characterized by SEM and XRD. However, we found that the film is not stable in nearly neutral aqueous solution. Therefore, although at the room temperature, ZIF-8 film could be successfully integrated into the surface of the electrode using alcohol phase synthesis method, but the stability of the system can not meet the requirements of the electrochemical application.(2) By surface chemical modification of the surface of the substrates, we obtained the substrates with different functional groups (such as-OH,-NH2, PVP,-COOH, PDA, BDC), and then the UiO-66 film growth conditions on these substrates were investigated. The results showed that both the modified-COOH glass substrate and FTO could grow dense, smooth UiO-66 and NH2-UiO-66 thin films. At the same time, by adjusting the concentration of reactants and using the secondary growth method could control the thickness of the films.(3) UiO-66 film is post-treated using PDMS-filling, CO2 supercritical drying and surfactant-assisted drying. And then the UiO-66/FTO system for molecular selectivity is detected by the electrochemistry method by using [Fe(phen)3]2+, [Fe(CN)6]3-, [Ru(NH3)6]3+as probe moleculars, the three methods can effectively reduce the defect or reduce the effect of the defect. The UiO-66 thin film by PDMS-filling method and supercritical CO2 drying method showed the absolute electrochemical molecular selectivity.