In‐Situ CeO2/CuO Heterojunction Electrocatalyst for CO2 Reduction to Ethylene

Abstract CeO 2 /CuO heterojunction composite catalysts were synthesized using a one‐step method, achieving the introduction of Ce species on nanoscale copper oxide (CuO) particles during the hydrothermal process. CeO 2 is primarily encapsulated the auxiliary catalyst CuO in the form of nanoparticles. On one hand, this protects the nanostructure of the substrate from damage and prevents the agglomeration of CuO nanoparticles. On the other hand, the bimetallic synergistic effect between Ce and Cu effectively improves the conductivity and catalytic activity of the catalyst, significantly enhancing the selectivity of the catalyst for electrochemical reduction of CO 2 to C 2 H 4 , while effectively suppressing the competing hydrogen evolution reaction (HER). By regulating the amount of CeO 2 introducing, a series of CeO 2 /CuO composite catalysts were designed. The results showed that the 15 % CeO 2 /CuO catalyst exhibited the best selectivity and catalytic activity for C 2 H 4 . At a low overpotential of −1.2 V, the 15 % CeO 2 /CuO catalyst demonstrated a current density of 14.2 mA cm −2 and achieved a Faradaic efficiency for ethylene as high as 65.78 %, which is 2.85 times the current density (j=4.98 mA cm −2 ) and 3.27 times the Faradaic efficiency for ethylene (FE C2H4 =20.13 %) of the undoped catalyst at the same potential. This work provides a feasible basis for achieving efficient CO 2 RR to C 2 products, and even multi‐carbon products.