A robust monolithic metal-organic framework with hierarchical porosity

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Engineering

Background:

• Metal-organic frameworks (MOFs) offer tunable properties for advanced applications.
• Developing robust, shape-controlled MOF materials remains a challenge.
• Hierarchical porosity is crucial for efficient mass transport and performance.

Purpose of the Study:

• To synthesize centimeter-scale monolithic UiO-66-NH2 gels with hierarchical porosity.
• To achieve controlled shape and enhance mechanical robustness of the MOF gels.
• To characterize the porosity and structure of the synthesized materials.

Main Methods:

• Preparation of ethanolic gels followed by drying to form xerogels and aerogels.
• Nitrogen (N2) sorption analysis to determine pore size distribution and surface area.
• Mercury (Hg) intrusion porosimetry for macropore and mesopore characterization.
• Focused Ion Beam-Scanning Electron Microscopy (FIB-SEM) for microstructural visualization.

Main Results:

• Successful synthesis of centimeter-scale monolithic UiO-66-NH2 xerogels and aerogels.
• Demonstrated control over shape and significant mechanical robustness of the monolithic structures.
• Verified hierarchical porosity across multiple length scales through N2 sorption, Hg intrusion, and FIB-SEM.

Conclusions:

• Centimeter-scale hierarchical porous UiO-66-NH2 monolithic gels can be fabricated with controlled shape and mechanical integrity.
• The developed method provides a pathway for scalable production of robust MOF materials.
• The characterized hierarchical porosity is key for potential applications in catalysis, separation, and sensing.