Cu₃N Nanocubes for Selective Electrochemical Reduction of CO₂ to Ethylene

Abstract

Understanding the Cu-catalyzed electrochemical CO₂ reduction reaction (CO₂RR) under ambient conditions is both fundamentally interesting and technologically important for selective CO₂RR to hydrocarbons. Current Cu catalysts studied for the CO₂RR can show high activity but tend to yield a mixture of different hydrocarbons, posing a serious challenge on using any of these catalysts for selective CO₂RR. Here, we report a new perovskite-type copper(I) nitride (Cu₃N) nanocube (NC) catalyst for selective CO₂RR. The 25 nm Cu₃N NCs show high CO₂RR selectivity and stability to ethylene (C₂H₄) at -1.6 V (vs reversible hydrogen electrode (RHE)) with the Faradaic efficiency of 60%, mass activity of 34 A/g, and C₂H₄/CH₄ molar ratio of >2000. More detailed electrochemical characterization, X-ray photon spectroscopy, and density functional theory calculations suggest that the high CO₂RR selectivity is likely a result of (100) Cu(I) stabilization by the Cu₃N structure, which favors CO-CHO coupling on the (100) Cu₃N surface, leading to selective formation of C₂H₄. Our study presents a good example of utilizing metal nitrides as highly efficient nanocatalysts for selective CO₂RR to hydrocarbons that will be important for sustainable chemistry/energy applications.