Hydrogen spillover through Matryoshka-type (ZIFs@)

Area of Science:

• Materials Science
• Chemistry
• Nanotechnology

Background:

• Hydrogen spillover is a known phenomenon in catalysis but its role in hydrogen storage within metal-organic frameworks (MOFs) is debated.
• The diffusion distance of dissociated hydrogen atoms in MOFs is not well understood, hindering their application in hydrogen storage.

Purpose of the Study:

• To provide experimental evidence for hydrogen spillover in microporous MOFs.
• To quantitatively measure the penetration depth of atomic hydrogen within MOFs.
• To investigate the migration of hydrogen atoms in MOFs under varying pressure conditions.

Main Methods:

• Synthesis of Matryoshka-type (ZIFs@)n-1ZIFs nanocubes (ZIF-8 or ZIF-67) with external Pt nanoparticles.
• Utilizing ZIF-8 shells as rulers and ZIF-67 cores as terminators to track H atom diffusion.
• Employing hydrogenolysis and CO2 hydrogenation reactions at normal and high pressures to trace H atom migration.

Main Results:

• Experimental confirmation of hydrogen spillover occurring in microporous MOFs at elevated temperatures.
• Quantitative measurement of atomic hydrogen penetration depths within the MOF structures.
• Demonstration of H atom migration over ZIF-8 under both normal and high-pressure CO2 hydrogenation.

Conclusions:

• This work establishes the occurrence of hydrogen spillover in MOFs, offering crucial insights for hydrogen storage applications.
• The developed Matryoshka-type MOF system effectively quantifies hydrogen atom diffusion distances.
• The findings pave the way for designing advanced MOFs for efficient hydrogen storage and related catalytic processes.