Ligand-tuning copper in coordination polymers for efficient electrochemical C-C coupling

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Copper (Cu) catalysts are crucial for electrochemical carbon dioxide (CO2) reduction to multicarbon products.
• Understanding the structure-function relationship of Cu catalysts is challenging due to dynamic active site reconstruction during electrolysis.

Purpose of the Study:

• To create stable, single-site Cu coordination polymer catalysts for CO2 electroreduction.
• To establish a molecular platform for studying structure-function relationships in CO2 electrolysis.
• To develop new catalyst design strategies for electrocatalysis.

Main Methods:

• Coordination of Cu with phenyl-1H-1,2,3-triazole derivatives to form stable coordination polymers.
• Electronic structure characterization using X-ray absorption spectroscopy (XAS) and ultraviolet-visible (UV-Vis) spectroscopy.
• Electrochemical analysis including CO diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) and in-situ Raman spectroscopy.
• Computational modeling using density functional theory (DFT) calculations.

Main Results:

• Homogenized, single-site Cu active sites were achieved in stable coordination polymer catalysts.
• Cu electronic structure was widely tunable by modulating the highest occupied molecular orbital (HOMO) energy of the ligands.
• A positive correlation was found between the binding strength of the *CO intermediate and the HOMO energies of the ligands.
• C-C coupling efficiency for C2 production was tuned over a broad range (0.26 to 0.86).

Conclusions:

• This work provides a molecular platform for investigating structure-function relationships in CO2 electrocatalysis.
• The developed catalysts and strategies enable efficient tuning of C-C coupling for CO2 reduction.
• The findings offer new catalyst design principles applicable to broader electrocatalytic applications.