Extrinsic hydrophobicity-controlled silver nanoparticles as efficient and stable catalysts for CO₂ electrolysis

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Economically viable electrochemical CO2 conversion requires high partial current density for valuable products.
• Cathode flooding accelerates hydrogen evolution reaction (HER) at high current densities, hindering CO2 electroreduction (CO2RR).

Purpose of the Study:

• To develop a strategy for enhancing CO2 electroreduction efficiency and stability.
• To prevent electrolyte flooding and maintain catalytic activity at high current densities.

Main Methods:

• Synthesis of partially ligand-derived silver nanoparticles (Ag-NPs).
• Electrochemical testing of Ag-NP electrodes for CO2 electroreduction.
• Analysis of catalyst degradation and cathode flooding using identical-location transmission electron microscopy and operando synchrotron-based X-ray computed tomography.

Main Results:

• Ag-NPs with lipid ligands prevented electrolyte flooding and maintained catalytic activity.
• Achieved high Faradaic efficiency for CO (>90%) and partial current density (298.39 mA cm⁻²).
• Demonstrated electrode stability under harsh conditions (3.4 V) with suppressed Ag particle splitting/detachment and uniform hydrophobicity.

Conclusions:

• Ligand-derived Ag-NPs offer an efficient strategy for designing active and durable electrocatalysts for CO2 electrolysis.
• Controlled hydrophobicity and suppressed particle detachment are key to preventing flooding and promoting CO2RR over HER.
• Maintained mass transfer of CO2 and facilitated triple phase boundary formation for efficient CO2RR.