Bimetallic metal organic frameworks with precisely positioned metal centers for efficient H₂ storage

Area of Science:

• Materials Science
• Inorganic Chemistry
• Nanotechnology

Background:

• Precise control over metal ion composition and placement in metal-organic frameworks (MOFs) is crucial for tuning their properties.
• Developing synthetic strategies for incorporating multiple metal species into MOFs with defined ratios remains a challenge.

Purpose of the Study:

• To demonstrate the precise control of palladium (Pd) and copper (Cu) metal ion ratios and positions within MOFs.
• To synthesize MOFs with uniformly distributed Pd-Cu open metal sites.
• To investigate the effect of Pd incorporation on hydrogen (H2) adsorption properties.

Main Methods:

• Synthesis of MOFs using predesigned Pd-Cu acetate metal clusters and tritopic organic linkers at room temperature.
• Characterization of the synthesized MOF structures to confirm the presence and distribution of Pd-Cu paddle wheel units.
• Measurement of H2 adsorption isotherms and calculation of isosteric heat of adsorption (Qst).

Main Results:

• Successfully synthesized MOFs with uniformly distributed Pd-Cu open metal sites in a precise 1:1 ratio.
• Demonstrated that the ratio and position of Pd and Cu ions can be controlled via predesigned metal clusters.
• Observed enhanced H2 affinity in Pd-incorporated MOFs, with Qst values reaching up to 8.9 kJ mol⁻¹.

Conclusions:

• Predesigned metal clusters offer a facile route for precise control over bimetallic composition in MOFs.
• The synthesized Pd-Cu MOFs exhibit uniform distribution of active sites and enhanced H2 adsorption capacity.
• This approach provides a pathway for designing advanced MOFs for gas storage and separation applications.