Cations Responsible for Varied CO₂RR Product Selectivity at High Overpotentials over Cu₂O Nanocubes

High Resolution Image Download MS PowerPoint Slide This study investigates the role of cations in tuning the structure and chemical state of Cu 2 O nanocubes during CO 2 reduction reactions (CO 2 RR) and how these changes impact product selectivity. Different cations (Li +, K +, Cs + ) in carbonate ( CO 3 2 − ) electrolytes have a significant effect on the dissolution and reprecipitation of Cu species, which alters the surface chemistry of electrodes. Li + promotes the dissolution of Cu, leading to a metallic surface that favors CH 4 production, while K + and Cs + stabilize the Cu oxide and hydroxide species on the surface, resulting in higher faradaic efficiency for C 2 H 4 . A combination of ex situ and in situ techniques, including X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS), and electrochemical surface-enhanced Raman spectroscopy (EC-SERS), demonstrates cation-induced changes in the Cu oxidation state and surface structure directly affecting CO 2 RR product selectivity.