Electrocatalytic CO2 reduction to ethylene over ZrO2/Cu-Cu2O catalysts in aqueous electrolytes

The conversion of CO<INF>2</INF> to C<INF>2</INF>H<INF>4</INF>, especially via the electrochemical CO<INF>2</INF> reduction reaction (CO<INF>2</INF>RR), is one of the promising approaches for utilizing CO<INF>2</INF> and producing important light olefins. Developing efficient catalysts is the key to realizing this conversion. In the present work, we have prepared several Cu-Zr bimetallic catalysts and assessed their performances in the CO<INF>2</INF>RR to C<INF>2</INF>H<INF>4</INF> using an H-type cell. Among the prepared catalysts, the bimetallic Cu-Zr catalyst (denoted as ZrO<INF>2</INF>/Cu-Cu<INF>2</INF>O) with a Cu/Zr molar ratio of 7/1 could achieve a 62.5% faradaic efficiency of ethene (FE<INF>C<INF>2</INF>H<INF>4</INF></INF>) with a high current density of 24 mA cm-2 at -1.28 V (vs. RHE) in 0.1 M KCl electrolyte. Characterization results indicated that the catalyst comprises ZrO<INF>2</INF> nanoparticles (NPs) supported on Cu-Cu<INF>2</INF>O NPs. The in situ Raman tests showed that a *COOH intermediate was involved during the reaction. DFT calculation further confirmed that the *COOH intermediate was favorably generated on Zr sites, which could be transferred to the adjacent Cu+ sites to couple and form *OCCO (or 2*CHO) dimers at the interface between Cu and Zr species. The dimer was further reduced to C<INF>2</INF>H<INF>4</INF> under the given conditions. The cooperation of the two components and interfaces resulted in the outstanding performance of the catalyst. We believe that the method to construct multicomponent interfaces to enhance FE and activity can also be used to design some other efficient catalysts for the CO<INF>2</INF>RR.