Synergetic enhancement of selectivity for electroreduction of CO₂ to C₂H₄ by crystal facet engineering and tandem catalysis over silver-incorporated-cuprous oxides

Electrochemical CO₂ reduction to C₂H₄ can provide a sustainable route to reduce globally accelerating CO₂ emissions and produce energy-rich chemical feedstocks. However, the poor selectivity in C₂H₄ electrosynthesis limits its implementation in industrially interesting processes. Herein, we report a composite structured catalyst composed of Ag and Cu₂O with different crystal faces to achieve highly efficient reduction of CO₂ to C₂H₄. The catalyst composed of Ag and octahedral Cu₂O enclosed with (111) facet exhibits the best CO₂ electroreduction performance, with the Faradaic efficiency (FE) and partial current density reaching 66.8% and 17.8 mA cm⁻² for C₂H₄ product at −1.2 V_RHE in 0.5 M KHCO₃, respectively. Physical characterization and electrochemical test analysis indicate that the high selectivity for C₂H₄ product stems from the synergistic effect of crystal faces control engineering and tandem catalysis. Specifically, Ag can provide optimal availability of CO intermediate by suppressing hydrogen evolution; subsequently, C–C coupling is promoted on the intimate surface of Cu₂O with facet-dependent selectivity. The insights gained from this work may be beneficial for designing efficient multicomponent catalysts for improving the selectivity of electrochemical CO₂ reduction reaction to generate C₂₊ products.