Conversion of Carbon Dioxide into Molecular-based Porous Frameworks

Area of Science:

• Materials Science
• Chemistry
• Sustainable Technology

Background:

• Converting inert carbon dioxide (CO2) into functional materials is crucial for a carbon-neutral society.
• Molecular-based porous materials like metal-organic frameworks (MOFs) and covalent-organic frameworks (COFs) offer designable structures.
• Synthetic routes for creating MOFs/COFs directly from CO2 building blocks remain largely unexplored.

Purpose of the Study:

• To review state-of-the-art studies on the conversion of CO2 into MOFs and COFs.
• To outline design principles for CO2-derived molecular building units.
• To categorize and demonstrate synthetic methodologies for CO2-based porous materials.

Main Methods:

• Categorization of synthetic methods into Type-I (one-step), Type-II (one-pot), and Type-III (multistep).
• Utilizing borohydride to convert CO2 into formate and formylhydroborate linkers for MOF synthesis.
• Employing amines for in situ transformation of CO2 into carbamate linkers and alkynylsilane precursors for carboxylate-based MOFs.
• Using formamide monomers for COF synthesis.

Main Results:

• Demonstrated the first examples of CO2-derived MOFs using borohydride, with pore sizes tunable by CO2 pressure.
• Achieved direct conversion of CO2 (even diluted) into carbamate-based MOFs stabilized by coordination interactions.
• Synthesized highly porous and stable carboxylate-based MOFs from CO2 with catalytic activity.
• Developed CO2-derived COFs from formamide exhibiting proton conduction.

Conclusions:

• Precise design of CO2-derived building units expands the structural diversity and functionality of MOFs/COFs.
• Future research should focus on expanding structural diversity using external fields and exploring functionalities like CO2 capture and transformation.
• This work lays the foundation for novel chemistry in converting CO2 into advanced porous materials.