Isomeric Cu(I) Azolate Frameworks Showing Contrasting Electrocatalytic CO₂ Reduction Selectivities and Stabilities

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Metal-organic frameworks (MOFs) are promising for electrocatalytic CO2 reduction (eCO2RR).
• Performance variations in MOFs are often linked to composition and stability, but coordination modes are less explored.
• Understanding these factors is crucial for designing efficient electrocatalysts.

Purpose of the Study:

• To investigate the impact of isomeric structures and coordination modes in Cu(I) triazolate frameworks on eCO2RR performance.
• To compare the selectivity, activity, and stability of MAF-2Fa and MAF-2Fb in eCO2RR.
• To elucidate the structure-performance relationships through experimental and computational methods.

Main Methods:

• Synthesis and characterization of isomeric Cu(I) triazolate frameworks (MAF-2Fa and MAF-2Fb).
• Electrocatalytic CO2 reduction reaction (eCO2RR) testing under various potentials.
• Operando electrochemical tests and computational simulations (e.g., DFT) to analyze mechanisms.

Main Results:

• MAF-2Fa, with a monotypic planar dinuclear Cu(I) coordination, achieved high C2H4 selectivity (53%) and C2 product yield (70%) with remarkable stability (>8 h).
• MAF-2Fb, featuring diverse Cu(I) coordination modes, exhibited low C2/C1 product ratios and poor stability (<1.5 h), decomposing into inorganic materials.
• Performance differences were correlated with distinct coordination environments and electronic structures.

Conclusions:

• The coordination mode of Cu(I) centers in MOFs significantly influences eCO2RR selectivity and catalyst stability.
• MAF-2Fa represents a highly selective and stable electrocatalyst for CO2 reduction to C2 products.
• This study provides insights into designing robust MOF-based electrocatalysts by controlling coordination structures.