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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - POPCRYSTAL (Precisely Oriented Porous Crystalline Films and Patterns)

Teaser

Metal-Organic Frameworks (MOFs) are porous crystalline solids composed of organic linkers and inorganic nodes. Both linkers and nodes are chemically mutable and can be judiciously chosen and assembled into porous crystals to afford multi-functional materials, either by...

Summary

Metal-Organic Frameworks (MOFs) are porous crystalline solids composed of organic linkers and inorganic nodes. Both linkers and nodes are chemically mutable and can be judiciously chosen and assembled into porous crystals to afford multi-functional materials, either by themselves or via infiltration of functional guests. These properties make MOFs highly desirable for use in technological applications, such as electronics, optics, sensing and separation. However their positioning on a substrate and their pore alignment in a film remains a barrier for their application to devices.
The POPCRYSTAL project will investigate ceramic-to-MOF conversions for the fabrication of fully oriented nanoporous films and patterns. Crystalline ceramics will be used as substrates for the controlled growth of oriented, porous, crystalline films and patterns. These novel platform materials will be employed for the fabrication of a functional device.
Property-directional dependant (anisotropic) materials are commonly observed in nature and underpin essential structural and biological functions (e.g. wood, bones). Mankind has adopted this concept as the basis of important technologies such as microelectronic, visualization and lightning technologies, etc. Therefore, the discovery of a protocol that can controlled structure-property relationship are of significant technological interest.
During the 5 years of the project, the research team will investigate protocols for the fabrication of different oriented MOFs films and patterns. Their functional properties will be studies and tested.

Work performed

Activities during the reported period:
1) Building up a team of young researchers (Post-docs, PhD students and students) to pursue the scientific goals indicated in the POPCRYSTAL proposal.
2) Evaluation, selection, purchase and setting up of equipment that will be necessary to carry out the activities related to deposition, synthesis, and characterization of the materials as described in the POPCRYSTAL proposal. This included the purchase of an Atomic Force Microscope (AFM) and a Raman microscope. Additionally, improvements were made on existing equipment, such as the enclosure that was built around the Dip Coater, intended for environmental control that is crucial for film depositions.
3) Working on the exploration of the system (WP1: Understanding) and its versatility (WP2: Extension).
Details of the performed studies:
Investigation of the protocol needed for the preparation of Cu(OH)2 nanobelts. During this task, the reproducibility was tested and optimized synthetic conditions were identified. The control of the aspect ratio is not yet obtained and this task is in progress.
Study of the protocol needed for the deposition of Cu(OH)2 nanobelts. Different conditions were investigated for the automatic deposition of aligned Cu(OH)2 nanobelts. We found now a protocol that has shown promising results. This protocol is currently under investigation.
Growth of MOFs from different ceramics:
• Cu2(CO3)H2O was successfully converted into HKUST-1 (MOF) [Riccò, R., et al. Chemistry of Materials 30.16 (2018)]
• CuO was transformed into Cu-CDC and Cu-BDC MOFs via vapour phase conversion [Stassin, Timothée, et al. Chemical Communications 55.68 (2019)]
• Co(CO3) was converted into ZIF-67 (MOF) using humid conditions at room temperature [manuscript in preparation]
• From ZnO, ZIF8 was produced in water in presence of proteins.
Growth of MOF-on-MOF proving the versatility of the oriented crystals via heteroepitaxial growth. Cu2(BPDC)2 and Cu2(BDC)2 MOF layers were grown preparing a multilayer MOF system from Cu(OH)2 [Ikigaki, K., et al., Angewandte Chemie 131.21 (2019)]

Final results

Progress was made mostly on WP1 and WP2 related topics. During the remaining time we expect to progress further along the projected tasks including WP3 and WP4, with the final goal of developing a proof-of-concept device.

WP1: Understanding – We have started by investigating the protocol needed for the preparation of Cu(OH)2 nanobelts, testing reproducibility and finding the most suitable synthetic conditions. We have studied the protocol needed for the deposition of Cu(OH)2 nanobelts. We have then explored different ceramic-to-MOF conversion routes. Additionally, we have performed preliminary in-situ studies of the conversion from Cu(OH)2 nanobelts to Cu2(BDC)2 with the AFM and SAXS to shed light on the underlying mechanisms that affords oriented MOF films. process.

WP2: Extension – We have been able to extend this ceramic-to-MOF concept to other materials, such as the successful transformation from Cu2(CO3)H2O into HKUST-1, from CuO into Cu-CDC and Cu-BDC MOFs via vapour phase conversion, from CoCO3 into ZIF-67 and from ZnO into ZIF-8. Additionally, the heteroepitaxial growth has been demonstrated for a multi-layer MOF-on-MOF approach creating complex composite materials. A computational screening study was performed to investigate ligands suitable for the preparation of oriented MOF films.

WP3: Control – we are currently investigating a method for an automatic deposition of the ceramic precursors to improve drastically the quality and reproducibility of the method as the deposition of oriented Cu(OH)2 nanobelts films is a key processing step. We expect to finalize this study and apply it to obtain high quality oriented MOF films with long-range order.

WP4: Fabrication – The final goal will be to apply the previous results in the development of a proof-of-concept device. The functional properties of the material will be investigated and the device tested.

Website & more info

More info: https://www.tugraz.at/institutes/ptc/research/falcaro-group/.