Oxides and Carbonates Accelerate Copper Instability in CO₂ Electroreduction

The electrochemical CO₂ reduction reaction (CO₂RR) is one of the key chemical transformations promoting the transition from fossil fuel-based energy systems to renewable systems. Copper (Cu)-based materials uniquely catalyze the production of multicarbon (C₂⁺) products from CO₂. Yet, copper operational instability limits long-term performance. Herein, we investigate the impact of the chemical nature of the initial Cu surface, particularly oxidation state and carbonate formation, on the structural and operational stability of Cu catalysts along with the reconstruction kinetics of the catalyst. We combine state-of-the-art well-defined catalysts with quasi-operando electrochemical liquid-phase transmission electron microscopy (ec-LPTEM) along with electrochemical characterization to learn about underlying differences. We demonstrate that catalysts with higher initial oxide content undergo faster structural reconstruction and suffer from faster operational deactivation. Interestingly, we find that Cu carbonates further exacerbate structural instability while also suppressing the CO₂RR activity. Our results highlight the critical role of oxides and carbonates in dictating the reconstruction pathways and durability of Cu under CO₂RR conditions, offering insights into tuning the Cu-based catalyst design for enhanced CO₂RR stability and efficiency.