Elaboration of metal organic framework hybrid materials with hierarchical porosity by electrochemical deposition–dissolution

Abstract

Rationally designed hierarchical macro-/microporous HKUST-1 electrodes were prepared via an electrochemical deposition-dissolution technique with the motivation to overcome diffusion limits that are typically occurring for conventional microporous MOFs. A colloidal crystal of silica spheres was prepared by the Langmuir-Blodgett (LB) technique. Using this crystal as a template, macroporous copper electrodes with a controlled number of pore layers were prepared via electrodeposition. After the removal of the template, the synthesis of HKUST-1 was performed via partial anodic dissolution of the copper surface in the presence of the organic linker, leading to the deposition of the HKUST-1 on the electrode surface with the designed macroporous structure. The macroporous Cu electrodes do not only behave as structural template but are also the Cu source for the formation of MOFs. Applied potential and deposition time allow to fine-tune the characteristics of the porous layer. The developed synthesis is rapid, occurs under mild conditions and therefore opens up various potential applications including catalysis, separation and sensing based on these hierarchical materials.

Chiral Macroporous MOF Surfaces for Electroassisted Enantioselective Adsorption and Separation

“…It is well known that several concepts can be applied to synthesize hierarchical MOFs including solvothermal synthesis, microwave synthesis, , and electrochemical methods . Among them, the electrochemical synthesis of MOFs to generate hierarchical porous structures is a very interesting choice and is still in the early stage of development. − Electrochemical concepts have the advantage that the synthesis of MOFs can be carried out under mild conditions (e.g., green solvent, low temperature, and low pressure) with low operating costs and short synthesis time.…”

Advanced technologies for the fabrication of MOF thin films

“…Note that only a limited number of MOFs have been processed by electrically driven deposition approaches. 16,23,24 (III) Casting of MOF powders…”

Mesoporous Metal–Organic Frameworks: Synthetic Strategies and Emerging Applications

“…While hierarchically porous materials can offer multiple scales of functionalities for more specific uses, it is of vital importance to combine this property with MOFs, Novel approaches like switchable solvent have been continuously established to synthesize mesoporosity‐contained MOFs, some of these emerging methods exhibit lack of textural control over the mesopores in MOFs, mesopores as participants in MOFs' hierarchical structures can lead to infinite possibilities for numerous studies and uses, e.g., hierarchical MOF electrode for supercapacitor, graphene/ZIF‐8 composites; hierarchical micro‐mesoporous MIL‐125 NUS‐6, and CuBTC; bimodal micro‐mesoporous MOFs nanocrystals; hollow hierarchical MOFs via selective acid etching; electrochemical deposition‐dissolution; double‐solvent mediated overgrowth of single‐crystalline microporous ZIF‐8 to gain hollow and mesoporous structure inside the nanocrystal ( Scheme ); chelating agent‐free, vapor‐assisted crystallization of hierarchical micro‐/mesoporous MIL‐125(Ti); competitive coordination for hierarchical MOF; enhanced CO 2 adsorption of Zr‐ and Hf‐UiO‐67 possessing hierarchical mesopores; MOF hierarchy templated from functional block co‐oligomer micelles; CO 2 transformation driven by visible light; and plasma‐etching of hierarchical pore development; a versatile strategy to synthesize functionalized mesoporous ZIF‐8 with mesopores having controllable size, shape, and spatial distribution after encapsulation and etching; and supramolecular templating of hierarchically porous MOF . Besides, Lu et al successfully synthesized porous organic frameworks via Yamamoto‐type Ullmann cross‐coupling reaction, and this strategy could be used to design and construct mesoporous MOFs …”