Bromine-Promoted Tandem Catalysis for C₂₊ Production from CO₂ Electroreduction

Area of Science:

• Electrochemistry
• Catalysis
• Materials Science

Background:

• Electrochemical carbon dioxide (CO2) reduction is a promising route for converting CO2 into valuable multicarbon chemicals.
• Achieving high selectivity in CO2 reduction, particularly for C2+ products, is challenging due to sluggish C-C coupling and competing reaction pathways on copper (Cu) catalysts.

Purpose of the Study:

• To design and investigate a novel bromine-mediated silver-copper (Ag-Cu) heterogeneous tandem catalyst for enhanced CO2 reduction to C2+ products.
• To understand the catalytic mechanism and the role of bromine in promoting C-C coupling.

Main Methods:

• Fabrication of a composite catalyst (Ag/AgBr/Cu2O) featuring a heterogeneous interface between AgBr-modified Ag nanoparticles and Cu2O.
• Electrochemical evaluation in an alkaline gas-diffusion electrolyzer to assess CO2 reduction performance.
• In situ electrochemical Fourier transform infrared (FTIR) spectroscopy to analyze surface intermediates.
• Density functional theory (DFT) calculations to elucidate reaction pathways and energetics.

Main Results:

• The Ag/AgBr/Cu2O-1 catalyst achieved a high Faradaic efficiency of 82.7% for C2+ production with a partial current density of 168.2 mA·cm−2.
• The catalyst significantly outperformed physically mixed Ag/Cu2O and pure Cu2O counterparts in CO2-to-C2+ conversion.
• Electrochemical FTIR and DFT studies revealed that bromine mediation enhances the surface coverage of *CO and *CHO intermediates, promoting asymmetric C-C coupling.

Conclusions:

• The developed bromine-mediated Ag-Cu tandem catalyst effectively promotes CO2-to-C2+ conversion by enhancing key intermediate accumulation and coupling.
• This work demonstrates the potential of bromine-mediated tandem catalysis as a strategy to overcome C-C coupling limitations in electrochemical CO2 reduction.