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

Abstract A copper‐oxide‐based catalyst enriched with paramelaconite (Cu₄O₃) is presented and investigated as an electrocatalyst for facilitating electroreduction of CO₂ to ethylene and other hydrocarbons. Cu₄O₃ is a member of the copper‐oxide family and possesses an intriguing mixed‐valance nature, incorporating an equal number of Cu⁺ and Cu²⁺ 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 Cu₄O₃ phase under CO₂ reduction conditions. The Cu₄O₃‐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 C₂₊/C₁ product ratio of 4.8 is achieved, with C₂₊ Faradaic efficiency over 61%. Additionally, the catalyst exhibits a stable performance for 24 h at a constant current density of 200 mA cm⁻².