Synergistic Effect of Binary Metal-phthalocyanine Catalysts for Electrochemical CO<sub>2</sub> Reduction

Electrochemical CO2 reduction reaction (CO2RR) is a promising approach for carbon recycling; however, its practical application is hindered by high overpotentials and the competing hydrogen evolution reaction. Here, we investigate metal phthalocyanines (MPcs; M = Fe, Co, Ni, and Cu) as molecular electrocatalysts and demonstrate that molecular-level integration of different MPcs can significantly enhance CO2RR performance. α-phase composite crystals composed of CuPc and MPc, denoted as α-(CuPc+MPc), were successfully synthesized to achieve molecular-level integration of heterometallic phthalocyanines, enabling close proximity between distinct metal active sites. Among the catalysts examined, α-(CuPc+FePc) exhibited the highest activity, delivering a CO production rate of 19.76 µmol min−1 with a Faradaic efficiency of 82.6 %, which is approximately 2.25 times higher than that of FePc alone. These results indicate that the molecular-level integration of heterometallic phthalocyanines induces a synergistic effect that promotes CO2-to-CO conversion, providing a viable strategy for designing efficient molecular CO2RR catalysts.