In situ surface/interface generation on Cu2O nanostructures toward enhanced electrocatalytic CO2 reduction to ethylene using operando spectroscopy

Abstract

Electrocatalytic CO₂ reduction reactions (CO₂RRs), an efficient method of converting carbon dioxide into valuable fuels and chemicals, are attractive as well as challenging. In this work, Cu₂O nanostructures with active facets (face-raised cubic structures (F-Cu₂O) with the (100) facet, octahedral structures (O-Cu₂O) with the (111) facet and edge- and corner-truncated octahedral structures (T-Cu₂O) with both the (100) and (111) facets) were synthesized by a wet chemical reduction method. The surface of Cu₂O nanostructures was reconstructed in situ to form Cu₂O/Cu with a highly active interface during the conversion of CO₂ into C₂H₄, which is named F-Cu₂O/Cu, O-Cu₂O/Cu and T-Cu₂O/Cu. The C₂H₄ selectivity on Cu₂O/Cu catalysts follows the order of O-Cu₂O/Cu < F-Cu₂O/Cu < T-Cu₂O/Cu, and the faradaic efficiencies of C₂H₄ are 11.2%, 24.9%, and 58.0% at −1.1 V versus the reversible hydrogen electrode, respectively. The experimental results combined with operando surface-enhanced Raman spectroscopy reveal that the Cu₂O/Cu interface enhances *CO adsorption and decreases the activation energy of C–C coupling, which is also supported by density functional theory (DFT) calculations. This study will pave a feasible pathway for electrochemical energy storage and convention by crystal facet engineering and interface engineering.