A study published in Nature Communications presents a method to create highly selective copper catalysts for converting carbon dioxide into ethylene using plasma treatment. The research team developed oxidized copper catalysts with lower overpotentials for CO₂ electroreduction and high selectivity towards ethylene (60%). By combining electrochemical measurements with microscopic and spectroscopic techniques, they found that Cu⁺ species are key for the reaction, challenging the traditional view that only metallic Cu is active. The study shows that the surface roughness of oxide-derived copper catalysts plays a partial role, while the presence of Cu⁺ is crucial for lowering the onset potential and enhancing ethylene selectivity. The plasma treatment, which involves oxygen and hydrogen plasmas, allows for tunable morphology and chemical state on polycrystalline Cu, resulting in a maximum faradaic selectivity of over 60% at -0.9 V versus RHE. The results indicate that Cu⁺ species remain stable on the surface during the reaction, contributing to the catalyst's performance. The study also highlights the importance of the oxidation state of the catalyst, showing that the initial oxidation state significantly affects the current density. The research provides insights into the mechanisms behind the improved activity and ethylene selectivity of oxide-derived Cu catalysts, offering design principles for more efficient ethylene-selective CO₂ reduction catalysts.A study published in Nature Communications presents a method to create highly selective copper catalysts for converting carbon dioxide into ethylene using plasma treatment. The research team developed oxidized copper catalysts with lower overpotentials for CO₂ electroreduction and high selectivity towards ethylene (60%). By combining electrochemical measurements with microscopic and spectroscopic techniques, they found that Cu⁺ species are key for the reaction, challenging the traditional view that only metallic Cu is active. The study shows that the surface roughness of oxide-derived copper catalysts plays a partial role, while the presence of Cu⁺ is crucial for lowering the onset potential and enhancing ethylene selectivity. The plasma treatment, which involves oxygen and hydrogen plasmas, allows for tunable morphology and chemical state on polycrystalline Cu, resulting in a maximum faradaic selectivity of over 60% at -0.9 V versus RHE. The results indicate that Cu⁺ species remain stable on the surface during the reaction, contributing to the catalyst's performance. The study also highlights the importance of the oxidation state of the catalyst, showing that the initial oxidation state significantly affects the current density. The research provides insights into the mechanisms behind the improved activity and ethylene selectivity of oxide-derived Cu catalysts, offering design principles for more efficient ethylene-selective CO₂ reduction catalysts.