Ampere-level CO₂ electroreduction to multi-carbon oxygenates in acidic electrolyte through surface microenvironment...

Area of Science:

• Electrochemistry
• Catalysis
• Materials Science

Background:

• Efficient electroreduction of carbon dioxide (CO2) to multi-carbon (C2+) oxygenates in acidic media at high current densities is a significant challenge.
• Existing copper-based catalysts often face limitations in selectivity and stability under demanding conditions for CO2 conversion.

Purpose of the Study:

• To develop a novel electrode material for enhanced CO2 electroreduction to C2+ oxygenates.
• To achieve high efficiency and selectivity for C2+ products under industrially relevant high current densities in acidic electrolytes.

Main Methods:

• Preparation of an ionic liquid (IL)-modified copper electrode (IL@Cu).
• Electrochemical evaluation of the IL@Cu electrode for CO2 reduction in an acidic electrolyte (0.5 M K2SO4, pH 1).
• Analysis of reaction mechanisms using electrochemical techniques and surface science insights.

Main Results:

• The IL@Cu electrode demonstrated a high Faradaic efficiency (FE) of 82.7% for C2+ products at a current density of 2.0 A cm-2.
• A single-pass carbon efficiency of 78.5% was achieved, with partial current densities for C2+ oxygenates and ethanol exceeding 1.2 A cm-2 and 1.0 A cm-2, respectively.
• Mechanism studies indicated that IL cations repel K+ ions, facilitating water access to the electrode surface and promoting C-C coupling.

Conclusions:

• The ionic liquid modification of copper electrodes significantly enhances CO2 electroreduction to C2+ oxygenates in acidic media.
• The IL@Cu electrode design offers a promising pathway for efficient and selective CO2 conversion at high current densities.
• Understanding the role of ion interactions and water accessibility is crucial for designing advanced electrocatalysts.