Theory-guided synthesis of heterostructured Cu@Cu0.4W0.6 catalyst towards superior electrochemical reduction of CO2 to C2 products

Rational design of high performance electrocatalyst towards electrochemical CO2 reduction (CO2RR) to C2 products remains a grand challenge. Herein, a heterostructured Cu@Cu0.4W0.6 catalyst was designed under the guidance of theoretical calculation towards CO2RR to C2 products and prepared by sequential reverse micro -emulsion and thermal reduction. The heterostructure of Cu@Cu0.4W0.6 catalysts were corroborated by X-ray diffraction (XRD) and transmission electron microscopy (TEM), which displayed spherical shape and a size of 15.6 +/- 0.5 nm. X-ray photoelectron spectroscopy illustrated more electron transfer from copper (Cu) to tungsten (W) in heterostructured Cu@Cu0.4W0.6 catalyst than that pure Cu0.4W0.6. The pure Cu0.4W0.6 catalyst is domi-nated by hydrogen evolution in CO2RR, while heterostructured Cu@Cu0.4W0.6 catalyst show much enhanced selectivity and activity towards C2 products, which is strongly dependent on the mass ratio of Cu to Cu0.4W0.6, ascribing to the Cu/Cu0.4W0.6 interface. Eventually, the Cu@Cu0.4W0.6 champion catalyst displays a Faradaic efficiency (FE) of 60.9% and a partial current density of 121.8 mA cm-2 at-1.0 V (vs. RHE) for C2 products in CO2RR in alkaline electrolyte. Computational studies indicated that the heterostructured Cu@Cu0.4W0.6 sup-presses hydrogen evolution and favors the production of CO and asymmetrical CO-CHO coupling, ascribing to the charge redistribution at the Cu/Cu0.4W0.6 interface. The high O affinity of W facilitates the rupture of C-O bond of *C2H3O intermediate and promotes the formation of ethylene. In-situ Raman spectroscopy revealed high surface coverage of bridging *CO and *CO-CHO intermediate for C2 products at 2660 cm-1 on Cu@Cu0.4W0.6, corroborating the CO-CHO coupling mechanism. This work highlights the importance of heterostructured Cu -based catalysts in tuning the CO2RR activity and selectivity of Cu-based materials.