Constructing Favorable Microenvironment on Copper Grain Boundaries for CO₂ Electro-conversion to Multicarbon Products

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Electrochemical CO2 reduction reaction (eCO2RR) is key for renewable energy storage.
• Producing multicarbon chemicals from CO2 is challenging but valuable.
• Copper (Cu) nanoparticles are promising catalysts for eCO2RR.

Purpose of the Study:

• To synthesize and characterize small Cu nanoparticles with enriched tiny grain boundaries (RGBs-Cu).
• To investigate the role of these grain boundaries in enhancing eCO2RR performance.
• To achieve high Faradaic efficiency (FE) for multicarbon products.

Main Methods:

• Spatial confinement and in situ electroreduction for nanoparticle synthesis.
• In situ spectroscopy and theoretical calculations for mechanistic studies.
• Electrochemical testing in neutral and alkaline electrolytes.

Main Results:

• RGBs-Cu nanoparticles exhibit enhanced adsorption of the *CO intermediate due to low-coordinated and disordered atoms at grain boundaries.
• In situ generated grain boundaries show excellent stability during eCO2RR.
• A stable *CO-rich microenvironment promotes C-C coupling.
• A peak FE of 77.3% for multicarbon products was achieved.
• Sustained stability of over 134 hours at -500 mA cm-2 was demonstrated.

Conclusions:

• Small Cu grain boundaries significantly enhance eCO2RR to multicarbon chemicals.
• The catalyst design offers a stable and efficient pathway for renewable energy storage.
• This work provides insights into catalyst design for selective CO2 conversion.