Hydrophobic Electrode Design for CO₂ Electroreduction in a Microchannel Reactor

Area of Science:

• Electrochemistry
• Materials Science
• Chemical Engineering

Background:

• Microchannel reactors offer intensified CO2 mass transfer.
• Wetted catalysts hinder CO2 diffusion to reaction sites.
• Hydrophobic catalysts are needed to improve CO2 accessibility.

Purpose of the Study:

• To synthesize a hydrophobic polytetrafluoroethylene (PTFE)-doped silver (Ag) nanocatalyst for CO2 electroreduction.
• To enhance CO2 mass transfer and electrocatalytic activity in microchannel reactors.
• To investigate the effect of PTFE doping on catalyst performance.

Main Methods:

• Galvanic replacement reaction (2Ag+ + Zn -> 2Ag + Zn2+) to synthesize Ag nanocatalysts.
• Incorporation of PTFE into the Ag matrix to create a hydrophobic catalyst layer.
• Electrochemical testing in a microchannel reactor and a high-pressure cell.

Main Results:

• Uniform PTFE-doped Ag nanocatalyst layer (77 μm thick) synthesized on a Zn rod.
• Optimal CO faradaic efficiency (FE_CO) of 96.19% achieved with 1 vol% PTFE and 30 min deposition.
• Catalyst maintained >90% FE_CO at 24 mA cm-2, outperforming non-PTFE catalysts by ~30%.
• Maximum CO partial current density (j_CO) reached 106.76 mA cm-2 at 9 bar under high pressure.

Conclusions:

• PTFE doping effectively enhances CO2 electroreduction by improving hydrophobicity and CO2 accessibility.
• The developed catalyst demonstrates superior activity and stability in microchannel reactors.
• High-pressure operation further boosts CO partial current density, indicating potential for industrial applications.