Dual-Element Modulation of Cu Active Sites toward Enhanced C-C Coupling in CO₂ Electroreduction

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Electrochemical CO2 reduction (eCO2R) on copper (Cu) is a promising pathway for producing multicarbon (C2+) products.
• Challenges include sluggish C-C coupling kinetics and competing hydrogen evolution, limiting efficiency and selectivity.
• Engineering Cu active sites is crucial for enhancing C2+ product formation.

Purpose of the Study:

• To develop a dual-element modulation strategy for copper catalysts.
• To investigate the effect of boron (B) and gold (Au) co-incorporation on Cu active sites for eCO2R.
• To enhance C-C coupling kinetics and suppress hydrogen evolution for improved C2+ production.

Main Methods:

• Synthesis of a heterostructured Au-B comodified Cu catalyst (AuBDC_h-1) with hollow nanocage domains.
• Electrochemical testing in flow cells and membrane electrode assemblies (MEAs) with 1 M KOH.
• In situ Raman spectroscopy and Density Functional Theory (DFT) calculations to analyze catalytic mechanisms.

Main Results:

• AuBDC_h-1 demonstrated a 3.21-fold increase in C2+ partial current density and a 2.24-fold improvement in cathodic energy efficiency compared to pristine Cu.
• The catalyst achieved 51.6% C2+ selectivity in a 5 cm2 MEA at -300 mA cm-2.
• In situ Raman and DFT calculations revealed enhanced CO binding and reduced C-C bond formation barriers, favoring C2+ coupling.

Conclusions:

• Dual modulation with B and Au effectively engineers Cu active sites, promoting selective CO2 to C2+ conversion.
• The AuBDC_h-1 catalyst shows superior performance in suppressing hydrogen evolution and methane formation.
• B-Au dual modulation presents a robust and transferable design principle for advancing CO2 electrolysis.