Remarkable electrocatalytic CO2 reduction with ultrahigh CO/H2 ratio over single-molecularly immobilized pyrrolidinonyl nickel phthalocyanine

Abstract How to efficiently obtain the value-added products through electrocatalytic CO2 reduction is highly desired while remains significant challenges. Herein, we report an extremely active and selective immobilized pyrrolidinonyl nickel phthalocyanine (PyNiPc) catalyst for electrocatalytic CO2 reduction, which was constructed by a built-in pyrrolidone group-assisted assembly strategy and presented single-molecular level dispersion of PyNiPc on carbon nanotubes. The resulting catalyst can predominantly produce CO in the electrocatalytic CO2 reduction, affording nearly 100 % Faradaic efficiency over a wide potential range with ultrahigh CO/H2 ratios up to 640. Besides, the extraordinary activity with a turnover frequency value of 1.3 × 104 h–1 at –0.93 V and durability were also achieved. Investigations unraveled the promotion effect of pyrrolidone groups in dispersion and catalysis. The reaction pathways over this catalyst were further explored by using in situ attenuated total reflection-infrared spectroscopy. This work offers a new understanding for constructing both active and selective molecular-based electrocatalysts.