High Performance Fe Porphyrin/Ionic Liquid Co-catalyst for Electrochemical CO2 Reduction

Area of Science:

• Electrochemistry
• Catalysis
• Materials Science

Background:

• Efficient catalytic reduction of carbon dioxide (CO2) is crucial for renewable energy storage and chemical feedstock production.
• Iron tetraphenylporphyrin (FeTPP) is a known catalyst for CO2 reduction, but its efficiency can be limited.

Purpose of the Study:

• To investigate the effect of an ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate, on the catalytic reduction of CO2.
• To improve the efficiency and kinetics of CO2 reduction using a homogeneous FeTPP-based catalyst.

Main Methods:

• Electrochemical reduction of CO2 in an aprotic electrolyte containing a proton source and FeTPP.
• Addition of 1-butyl-3-methylimidazolium tetrafluoroborate as a co-catalyst.
• In situ formation of the [Fe(0)TPP](2-) homogeneous catalyst.

Main Results:

• The ionic liquid promoted the in situ formation of the catalyst at a less negative potential.
• Reduced overpotential for CO2 reduction to 670 mV and increased electron transfer kinetics.
• High Faradaic efficiency for CO production (93%) and a high turnover number (2,740,000 over 4 hours).
• A four-fold increase in turnover frequency (TOF) compared to the system without the ionic liquid.

Conclusions:

• The addition of 1-butyl-3-methylimidazolium tetrafluoroborate significantly enhances the performance of FeTPP-catalyzed CO2 reduction.
• This co-catalysis approach offers a more efficient and kinetically favorable pathway for CO2 conversion.
• The findings present a promising strategy for sustainable energy storage and chemical production.