Reduction of carbon dioxide at a plasmonically active copper-silver cathode.

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Electrochemical reduction of carbon dioxide (CO2) is a key technology for renewable energy storage.
• Copper-based catalysts are widely studied for CO2 reduction but often suffer from poor selectivity.
• Plasmonic materials offer potential for enhancing catalytic reactions through light-matter interactions.

Purpose of the Study:

• To develop a plasmonically active cathode for enhanced CO2 reduction selectivity.
• To investigate the effect of light illumination on CO2 reduction pathways at silver-coated copper nanostructures.
• To elucidate the role of plasmonic effects in directing CO2 reduction product distribution.

Main Methods:

• Electrochemical deposition of copper nanostructures.
• Coating copper nanostructures with silver to create plasmonic cathodes.
• Illumination of the cathode with 365 nm light during CO2 reduction.
• Analysis of CO2 reduction products using gas chromatography and other analytical techniques.
• Temperature-dependent control experiments to rule out thermal effects.

Main Results:

• Illumination selectively enhanced 5 out of 14 observed CO2 reduction products.
• Hydrogen evolution was suppressed under illumination.
• At low overpotentials, carbon monoxide (C1 product) was promoted.
• At high overpotentials, ethylene, methane, formate, and allyl alcohol (C2/C3 products) were enhanced.
• Selective promotion of C1 products and C2/C3 products with double carbon bonds was observed under illumination.
• Temperature-dependent studies confirmed that local heating was not responsible for the observed selectivity changes.

Conclusions:

• Plasmonic enhancement using light can significantly improve the selectivity of CO2 reduction at copper electrodes.
• The study demonstrates a novel approach to tune CO2 reduction pathways using plasmonically active materials.
• Further research is needed to fully understand the underlying plasmonic mechanisms for selective CO2 reduction.