Regulated Second-sphere Coordination in Amorphous Metal-organic Framework for Efficient CO₂ Fixation

Area of Science:

• Materials Science
• Catalysis
• Nanotechnology

Background:

• Photocatalytic CO2 fixation is crucial for carbon neutrality.
• Current methods face limitations due to rigid structures and poor orbital overlap.
• Developing efficient catalysts for CO2 conversion remains a significant challenge.

Purpose of the Study:

• To introduce a second-sphere coordination regulation strategy for enhancing photocatalytic CO2 fixation.
• To demonstrate the effectiveness of amorphous metal-organic frameworks (a-MOFs) in controlling the secondary coordination sphere.
• To optimize orbital overlap and catalytic site accessibility for improved CO2 capture.

Main Methods:

• Construction of amorphous metal-organic frameworks (a-MOFs) with tailored metal-metal coordination in the secondary building unit (SBU).
• Utilizing in situ experiments and theoretical calculations to analyze structural and electronic properties.
• Evaluating photocatalytic CO2 fixation performance and photo-assisted Li-CO2 battery performance.

Main Results:

• The a-MOF architecture facilitates flexible dinuclear motifs, enhancing spatial proximity and s-π* orbital overlap.
• Second-sphere engineering increases electron donating capacity and promotes efficient electron injection into CO2.
• Photocatalytic CO2 fixation yields doubled compared to crystalline counterparts.
• Photo-assisted Li-CO2 battery exhibited higher discharge voltage and a fourfold capacity increase.

Conclusions:

• Tailoring the secondary coordination sphere via a-MOFs is an effective strategy for enhancing photocatalytic CO2 fixation.
• This approach optimizes the local microenvironment of open metal sites, improving small molecule binding affinity.
• The developed a-MOF shows significant potential for efficient CO2 capture and conversion applications.