Steering CO₂ Electroreduction Selectivity U-Turn to Ethylene by Cu-Si Bonded Interface.

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Copper (Cu) is a unique catalyst for electrochemical carbon dioxide reduction (CO2RR) due to its ability to produce multicarbon products.
• Designing efficient Cu-based catalysts and understanding their structure-activity relationships for CO2RR remain significant challenges.

Purpose of the Study:

• To rationally design a core-shell structured silica-copper catalyst (p-Cu@m-SiO2) with direct Cu-Si bonding for efficient and selective CO2RR.
• To elucidate the reaction mechanism and structure-activity relationship governing CO2RR selectivity on the designed catalyst.

Main Methods:

• Synthesis of a core-shell structured silica-copper catalyst (p-Cu@m-SiO2) via direct Cu-Si bonding.
• Electrochemical characterization including current density measurements.
• Mechanistic studies using kinetic isotopic effect, *in situ* attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR), and density functional theory (DFT) calculations.

Main Results:

• The p-Cu@m-SiO2 catalyst significantly enhanced CO2RR selectivity towards C2H4, with the C2H4/CH4 product ratio increasing from 0.6 to 14.4.
• Achieved high current density up to 450 mA cm-2.
• Identified that the SiO2 shell stabilizes the *H intermediate and the Cu-Si interface promotes the coupling of *CHO and *CO intermediates to form C2H4.

Conclusions:

• The direct Cu-Si bonding in the p-Cu@m-SiO2 core-shell structure is crucial for high C2H4 selectivity in CO2RR.
• The catalyst design effectively inhibits the hydrogen evolution reaction and promotes C-C coupling.
• This work presents a viable strategy for developing advanced Cu-based catalysts for selective CO2 conversion into valuable multicarbon products.