Grain Boundary Engineering in 3D Porous Silver Electrocatalysts for Enhanced CO₂-to-CO Conversion

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Silver is a selective electrocatalyst for CO2 reduction to CO.
• A key challenge is the trade-off between silver's catalytic activity and stability.
• Optimizing silver catalysts requires addressing both morphological and crystallographic features.

Purpose of the Study:

• To develop a novel silver catalyst with improved activity and stability for CO2 electroreduction.
• To investigate the structure-activity relationship of a three-dimensional coral-like porous silver (CP-Ag) catalyst.
• To understand how engineered morphology and grain boundaries influence catalytic performance.

Main Methods:

• Seed-assisted nanoparticle attachment synthesis to create a 3D coral-like porous silver (CP-Ag) architecture.
• Electrochemical characterization including Faradaic efficiency (FE) and current density measurements.
• Long-term stability testing in a flow cell setup.

Main Results:

• CP-Ag exhibited >90% FE for CO over a wide potential range (-0.6 to -1.0 V vs. RHE).
• Achieved a 2-times higher current density compared to normal Ag NPs.
• Demonstrated sustained high FE for CO (~90%) for approximately 40 hours at -50 mA cm-2.

Conclusions:

• The 3D coral-like morphology enhances active sites and charge transfer.
• Stable grain boundaries between Ag NPs contribute to increased reaction activity.
• Optimized binding on Ag (100) facets promotes CO intermediate formation, boosting overall performance.