Pressure-induced amorphization and porosity modification in a metal-organic framework

Area of Science:

• Materials Science
• Chemistry
• Nanotechnology

Background:

• Metal-organic frameworks (MOFs) are porous materials with tunable properties.
• Understanding the mechanical behavior of MOFs under pressure is crucial for their application.
• ZIF-8 is a well-studied MOF known for its potential in gas storage and separation.

Purpose of the Study:

• To investigate the impact of industrially relevant pressures on the structure and porosity of ZIF-8.
• To determine the compressibility and pressure-induced structural changes in ZIF-8.
• To explore pressure as a method for post-synthetic modification of MOFs.

Main Methods:

• In situ powder X-ray diffraction to monitor structural changes under pressure.
• Sorption measurements on pressure-treated ZIF-8 samples.
• Calculation of the bulk modulus to quantify compressibility.

Main Results:

• ZIF-8 exhibits high compressibility with a bulk modulus of 6.52(35) GPa, making it the most compressible MOF reported.
• Irreversible pressure-induced amorphization occurs in ZIF-8 beyond 0.34 GPa.
• Pressure-amorphized ZIF-8 retains porosity but shows altered sorption characteristics.

Conclusions:

• Pressure is an effective and scalable method for modifying the functional properties of MOFs like ZIF-8.
• This pressure-induced modification is achievable at lower pressures compared to other porous materials, indicating industrial relevance.
• The findings open new avenues for tailoring MOF properties through mechanical stimuli for diverse applications.