Phase-Inversion Induced 3D Electrode for Direct Acidic Electroreduction CO₂ to Formic acid.

Area of Science:

• Electrochemistry
• Materials Science
• Chemical Engineering

Background:

• Direct electrochemical CO2 reduction to formic acid (FA) is hindered by FA's acidity and competing hydrogen evolution.
• Existing electrodes face challenges in managing reaction conditions for efficient FA production.

Purpose of the Study:

• To develop a novel 3D porous electrode (TDPE) for efficient direct electrochemical CO2 reduction to FA.
• To investigate the TDPE's performance in acidic conditions and understand the reaction mechanism.

Main Methods:

• Fabrication of a TDPE using a simple phase inversion method.
• Electrochemical reduction of CO2 to FA in acidic media.
• Kinetic isotopic effect experiments to elucidate the reaction mechanism.
• Performance evaluation in a flow cell setup.

Main Results:

• The TDPE demonstrated improved mass transport and created a beneficial local pH gradient under acidic conditions.
• Kinetic isotopic effect studies indicated proton transfer as a rate-determining step at pH 1.8.
• A maximum FA Faradaic efficiency of 89.2% was achieved at pH 2.7 in a flow cell.
• A FA concentration of 0.1 M was generated.

Conclusions:

• The TDPE facilitates direct electrochemical CO2 reduction to FA in acidic media by enhancing local pH and mass transport.
• The phase inversion method provides a facile route for integrating catalytic and gas-liquid partition functions into a single electrode structure.
• This approach offers a promising strategy for the direct production of FA via electrochemical CO2 reduction.