Paramelaconite‐Enriched Copper‐Based Material as an Efficient and Robust Catalyst for Electrochemical Carbon Dioxide Reduction

A copper‐oxide‐based catalyst enriched with paramelaconite (Cu 4 O 3 ) is presented and investigated as an electrocatalyst for facilitating electroreduction of CO 2 to ethylene and other hydrocarbons. Cu 4 O 3 is a member of the copper‐oxide family and possesses an intriguing mixed‐valance nature, incorporating an equal number of Cu + and Cu 2+ ions in its crystal structure. The material is synthesized using a solvothermal synthesis route and its structure is confirmed via powder X‐ray diffraction, transmission electron microscope based selected area electron diffraction, and X‐ray photoelectron spectroscopy. A flow reactor equipped with a gas diffusion electrode is utilized to test a copper‐based catalyst enriched with the Cu 4 O 3 phase under CO 2 reduction conditions. The Cu 4 O 3 ‐rich catalyst (PrC) shows a Faradaic efficiency for ethylene over 40% at 400 mA cm −2 . At −0.64 versus reversible hydrogen electrode, the highest C 2+ /C 1 product ratio of 4.8 is achieved, with C 2+ Faradaic efficiency over 61%. Additionally, the catalyst exhibits a stable performance for 24 h at a constant current density of 200 mA cm −2 .