Two viologen-functionalized pyrazolide-based metal–organic frameworks for efficient CO2 photoreduction reaction

The light-triggered CO2 catalytic reduction process of high efficiency is highly desirable but challenging. Herein, we present two viologen-based metal–organic frameworks (M-VOF, where M = Co and Ni) as ideal platforms for photocatalytic CO2 reduction. Co-VOF exhibits a high CO evolution rate of 458.66 μmol g−1 h−1 under light irradiation, while Ni-VOF provides a CO evolution rate of 52.33 μmol g−1 h−1 with superior durability. Experimental studies reveal that the viologen-based frameworks play an important role in the transfer and separation of the charge carriers in the catalytic system. This work provides not only a superior Co-VOF catalyst but also promotes in-depth insight into the structure–activity relationships toward the activation and photoreduction of CO2.