Bio-inspired hydrophobicity promotes CO₂ reduction on a Cu surface

Area of Science:

• Electrochemistry
• Materials Science
• Sustainable Chemistry

Background:

• Aqueous electrocatalytic reduction of carbon dioxide (CO2) is crucial for sustainable fuel production.
• Copper (Cu) is unique for catalyzing multicarbon product formation but suffers from low selectivity due to competing hydrogen evolution.
• Improving CO2 reduction selectivity is key to efficient energy conversion.

Purpose of the Study:

• To develop a superhydrophobic copper electrode for enhanced CO2 electrocatalytic reduction.
• To investigate the effect of surface hydrophobicity on CO2 reduction selectivity.
• To understand the mechanism behind improved selectivity on hydrophobic surfaces.

Main Methods:

• Fabrication of hierarchically structured Cu dendrites.
• Surface modification using 1-octadecanethiol to create superhydrophobicity.
• Electrocatalytic CO2 reduction experiments at neutral pH.
• Comparison of performance between hydrophobic and hydrophilic Cu electrodes.

Main Results:

• The superhydrophobic Cu electrode achieved 56% Faradaic efficiency for ethylene and 17% for ethanol.
• Hydrophilic Cu electrodes showed significantly lower efficiencies (9% ethylene, 4% ethanol).
• Gas trapping at the hydrophobic surface was identified as the mechanism for increased CO2 concentration and selectivity.

Conclusions:

• Superhydrophobic surfaces significantly enhance CO2 electrocatalytic reduction selectivity towards multicarbon products.
• Surface hydrophobicity is a critical factor influencing CO2 reduction efficiency.
• This strategy offers a promising route for developing advanced electrocatalysts for CO2 conversion.