Enhancing the CO₂-to-CO Conversion from 2D Silver Nanoprisms via Superstructure Assembly

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Electrochemical reduction of carbon dioxide (CO2) is vital for producing fuels and chemicals.
• Nanostructured silver (Ag) catalysts show promise for CO2-to-CO conversion.
• Limited active site density and unclear activity hinder practical applications of Ag catalysts.

Purpose of the Study:

• To develop a superstructure design for Ag catalysts to maximize active site exposure.
• To enhance selectivity and efficiency in electrochemical CO2 reduction.
• To identify the specific active sites responsible for CO2 conversion.

Main Methods:

• Fabrication of Ag superstructures via self-assembly of 2D Ag nanoprisms.
• Electrochemical measurements on individual nanoprisms and superstructures.
• Analysis of edge-to-basal plane ratios and their impact on catalytic activity.

Main Results:

• Vertically stacked Ag nanoprisms expose >95% of edge sites.
• Achieved enhanced CO2-to-CO selectivity (>90% for 100 h) with a low overpotential (152 mV).
• Identified edge ribs as active sites, showing a significant decrease in onset potential (~400 mV) compared to basal planes.

Conclusions:

• The superstructure design effectively maximizes active edge sites for superior CO2 electroreduction.
• Edge ribs of Ag nanoprisms are the primary active sites for CO2-to-CO conversion.
• This approach offers a pathway for practical electrocatalytic devices for CO2 utilization.