CuNCN derived Cu-based/CxNy catalysts for highly selective CO2 electroreduction to hydrocarbons

Copper (Cu) has been proved as an efficient catalyst in carbon dioxide electrochemical reduction reaction (CO2RR) towards hydrocarbons, but still suffers from low selectivity and poor stability. Herein, Cu-based/CxNy catalysts were fabricated by facile pyrolysis of CuNCN in sealed quartz tubes. It is found that CuNCN pyrolyzed at 300 °C (CuNCN-300) exhibits a high C2H4 Faradaic efficiency of 48.5% at 500 mA cm-2. However, increasing the pyrolysis temperature above 400 °C gives rise to CH4 being the predominant product and CuNCN-500 achieves CH4 Faradaic efficiencies of 66.3% at 300 mA cm-2. Combining experimental and DFT calculation results, Cu3N plays a crucial role in the formation of C2H4, while tri-s-triazine units in CuNCN-500 reduce the barrier of *CO hydrogenation to *CHO and retard C-C coupling on Cu surface. These findings mark the significance of precise tailoring of the synergistic effect between g-C3N4 and different Cu species for achieving the desired selectivity during CO2RR.