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

Copper (Cu), with the advantage of producing a deep reduction product, is a unique catalyst for the electrochemical reduction of CO2 (CO2RR). Designing a Cu-based catalyst to trigger CO2RR to a multicarbon product and understanding the accurate structure–activity relationship for elucidating reaction mechanisms still remain a challenge. Herein, we demonstrate a rational design of a core–shell structured silica-copper catalyst (p-Cu@m-SiO2) through Cu–Si direct bonding for efficient and selective CO2RR. The Cu–Si interface fulfills the inversion in CO2RR product selectivity. The product ratio of C2H4/CH4 changes from 0.6 to 14.4 after silica modification, and the current density reaches a high of up to 450 mA cm–2. The kinetic isotopic effect, in situ attenuated total reflection Fourier-transform infrared spectra, and density functional theory were applied to elucidate the reaction mechanism. The SiO2 shell stabilizes the *H intermediate by forming Si–O–H and inhibits the hydrogen evolution reaction effectively. Moreover, the direct-bonded Cu–Si interface makes bare Cu sites with larger charge density. Such bare Cu sites and Si–O–H sites stabilized the *CHO and activated the *CO, promoting the coupling of *CHO and *CO intermediates to form C2H4. This work provides a promising strategy for designing Cu-based catalysts with high C2H4 catalytic activity.