Unveiling the Synergistic Effect between Graphitic Carbon Nitride and Cu2 O toward CO2 Electroreduction to C2 H4.

Electrochemically reducing carbon dioxide (CO2 RR) to ethylene is one of the most promising strategies to reduce carbon dioxide emissions and simultaneously produce high value-added chemicals. However, the lack of catalysts with excellent activity and stability limits the large-scale application of this technology. In this work, a graphitic carbon nitride (g-C3 N4 )-supported Cu2 O composite was fabricated, which exhibited a 32.2 % faradaic efficiency of C2 H4 with a partial current density of -4.3 mA cm-2 at -1.1 V vs. reversible hydrogen electrode in 0.1 m KHCO3 electrolyte. The introduction of g-C3 N4 support not only enhanced the uniform dispersion of Cu2 O nanocubes, but also stabilized the important *CO intermediates. Moreover, the g-C3 N4 itself had a good activity of reducing CO2 to form *CO, which enriched the key intermediates of C-C coupling around cuprous oxide. The findings highlight the importance of the g-C3 N4 support, a unique two-dimensional material, including not only the strong CO2 adsorption and activation capacity but also its synergistic effect with the cuprous oxide in CO2 RR selectivity.