Intensified Electrocatalytic CO₂ Conversion in Pressure-Tunable CO₂ -Expanded Electrolytes

Area of Science:

• Electrochemistry
• Green Chemistry
• Materials Science

Background:

• Electrocatalytic reduction of carbon dioxide (CO2) is crucial for sustainable energy and chemical production.
• Achieving high CO2 concentrations in electrolyte solutions is a key challenge for efficient electrocatalysis.
• CO2-expanded Electrolytes (CXEs) offer a novel approach to increase dissolved CO2 levels.

Purpose of the Study:

• To investigate the electrocatalytic performance of CO2 reduction in CXE media.
• To determine the effect of CO2 pressure and concentration on CO2 to CO conversion rates.
• To understand the mechanisms behind catalytic intensification in CXE media.

Main Methods:

• Preparation of acetonitrile-based CO2-expanded Electrolytes (CXEs) at mild CO2 pressures (<5 MPa).
• Electrocatalytic reduction of CO2 using a polycrystalline gold electrode in CXE media.
• Analysis of CO2 conversion rates and selectivity under varying CO2 pressures and concentrations.

Main Results:

• CXE media enabled multimolar CO2 concentrations and significant volumetric expansion.
• CO2 to CO conversion rates were enhanced by up to an order of magnitude compared to near-ambient conditions.
• An optimal dissolved CO2 concentration of approximately 5 m was observed for maximum catalytic activity.
• High CO2 pressures led to attenuated catalysis, partly due to increased solution resistance.

Conclusions:

• Pressure-tunable CXE media significantly intensify electrocatalytic CO2 reduction by alleviating substrate starvation.
• CO2 pressure is a critical variable for optimizing the efficiency of electrocatalytic CO2 conversion.
• CXE media represent a promising strategy for advancing sustainable CO2 utilization technologies.