A conductive catecholate-based framework coordinated with unsaturated bismuth boosts CO₂ electroreduction to formate.

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Bismuth-based metal-organic frameworks (Bi-MOFs) are promising for CO2 conversion.
• Poor conductivity and saturated coordination limit the performance of existing Bi-MOFs.

Purpose of the Study:

• To design and synthesize a conductive Bi-MOF with enhanced performance for electrochemical CO2-to-formate conversion.
• To investigate the structure-activity relationship and catalytic mechanism of the new material.

Main Methods:

• Single-crystal X-ray diffraction to determine topology.
• Electron paramagnetic resonance spectroscopy to confirm unsaturated coordination sites.
• Electrochemical testing in a flow cell for CO2 reduction.
• In situ ATR-FTIR and DFT calculations for mechanistic studies.

Main Results:

• A novel conductive catecholate-based framework, Bi-HHTP, was constructed with a unique zigzagging corrugated topology.
• Bi-HHTP demonstrated excellent electrical conductivity (1.65 S m-1) and unsaturated Bi sites.
• Achieved 95% selectivity for formate production with a turnover frequency of 576 h-1.
• The catalyst structure remained stable post-reaction, and DFT calculations identified *COOH species as key intermediates and rate-determining steps.

Conclusions:

• The rational design of conductive and stable Bi-MOFs can significantly improve electrochemical CO2 reduction performance.
• Unsaturated coordination Bi sites are crucial active sites for efficient CO2-to-formate conversion.
• This work offers valuable insights for developing advanced catalysts for CO2 utilization.