A Direct Grain-Boundary-Activity Correlation for CO Electroreduction on Cu Nanoparticles

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Electrochemical reduction of carbon monoxide (CO) to C2+ products offers a pathway for renewable energy conversion into fuels and chemicals.
• Conventional copper (Cu) electrodes exhibit low energy efficiency and poor selectivity for CO reduction over hydrogen evolution.
• Lack of quantitative structure-activity relationships hinders the design of improved Cu-based catalysts.

Purpose of the Study:

• To establish a quantitative structure-activity relationship for copper catalysts in CO electrochemical reduction.
• To investigate the role of grain boundary (GB) density in copper nanoparticles (NPs) on catalytic performance.
• To develop high-performance Cu catalysts for selective CO reduction to valuable C2+ products.

Main Methods:

• Fabrication of copper nanoparticle (Cu NP) electrodes on carbon nanotubes (Cu/CNT) with varying GB densities.
• Quantification of GB density using transmission electron microscopy (TEM).
• Electrochemical characterization of CO reduction activity and selectivity at different potentials.

Main Results:

• CO reduction activity is directly correlated with the density of grain boundaries (GBs) in Cu NPs.
• Specific activity for CO reduction to ethanol and acetate shows a linear proportionality to the fraction of GB surface terminations.
• GB-rich Cu/CNT electrodes achieve significant CO reduction activity at moderate overpotentials, reaching a mass activity of ~1.5 A/g Cu and >70% Faradaic efficiency at -0.3 V.

Conclusions:

• Grain boundary density serves as a critical design principle for enhancing Cu-catalyzed CO electrochemical reduction.
• GB-rich Cu/CNT electrodes represent a new class of nanoparticle catalysts with superior performance for CO conversion.
• This study provides a pathway for developing efficient catalysts for converting renewable energy into valuable chemicals and fuels.