Cu-Zn-based alloy/oxide interfaces for enhanced electroreduction of CO2 to C2+ products

Abstract

The electrochemical CO2 reduction reaction to produce multi-carbon (C2+) hydrocarbons or oxygenate compounds is a promising route to obtain a renewable fuel of high energy density. However, producing C2+ at high current densities is still a challenge. Herein, we develop a Cu-Zn alloy/Cu-Zn aluminate oxide composite electrocatalytic system for enhanced conversion of CO2 to C2+ products. The Cu-Zn-Al-Layered Double Hydroxide (LDH) is used as a precursor to decompose into uniform Cu-Zn oxide/Cu-Zn aluminate pre-catalyst. Under electrochemical reduction, Cu-Zn oxide generates Cu-Zn alloy while Cu-Zn aluminate oxide remains unchanged. The alloy and oxide are closely stacked and arranged alternately, and the aluminate oxide induces the strong electron interaction of Cu, Zn and Al, creating a large number of highly active reaction interfaces composed of 0 to +3 valence metal sites. With the help of the interface effect, the optimized Cu9Zn1/Cu0.8Zn0.2Al2O4 catalyst achieves a Faradaic efficiency of 88.5% for C2+ products at a current density of 400 mA cm−2 at −1.15 V versus reversible hydrogen electrode. The in-situ Raman and attenuate total reflectance-infrared absorption spectroscopy (ATR-IRAS) spectra show that the aluminate oxide at the interface significantly enhances the adsorption and activation of CO2 and the dissociation of H2O and strengthens the adsorption of CO intermediates, and the alloy promotes the C–C coupling to produce C2+ products. This work provides an efficient strategy to construct highly active reaction interfaces for industrial-scale electrochemical CO2RR.