Small Interparticle Spacing in Catalyst Layers Forms an Expansive Triple-Phase Interface for Boosting the Current...

Area of Science:

• Electrochemistry
• Materials Science
• Chemical Engineering

Background:

• Efficient carbon dioxide (CO2) electrolysis requires high current density and selectivity for valuable products.
• The triple-phase interface (catalyst, electrolyte, gas) is critical for CO2 electrolysis, acting as the active reaction site.
• Copper nanoparticles (CuNPs) are promising catalysts for CO2 conversion.

Purpose of the Study:

• To establish design principles for copper nanoparticle (CuNP) based triple-phase interfaces for ultra-high current density CO2 electrolysis.
• To investigate the relationship between catalyst properties and electrochemical performance for multicarbon (C2+) product formation.
• To optimize electrode design for enhanced CO2 electrolysis.

Main Methods:

• Systematic evaluation of CuNP electrodes under high-current-density (>1 A cm-2) electrolysis conditions.
• Analysis of correlations between electrochemical performance (e.g., partial current density for C2+ production, jC2+), Faradaic efficiency, and catalyst physicochemical properties.
• Characterization of catalyst layer properties, focusing on interparticle spacing and electrolyte penetration.

Main Results:

• Identified a correlation between the average interparticle spacing in the catalyst layer and the maximum partial current density for C2+ production (jC2+).
• Demonstrated that smaller interparticle spacings enhance jC2+ by controlling electrolyte penetration and expanding the triple-phase interface.
• Achieved a record jC2+ of 2.00 A cm-2 with 80.1% Faradaic efficiency using an optimized electrode with 59.4 nm average interparticle spacing.

Conclusions:

• Optimizing interparticle spacing in CuNP catalyst layers is a viable strategy to enhance CO2 electrolysis performance.
• The design of the triple-phase interface, specifically managing electrolyte behavior within the catalyst layer, is crucial for achieving ultra-high current densities.
• This work provides key insights for designing advanced electrodes for efficient CO2 conversion into high-value multicarbon products.