Porous organic polymers are efficient photocatalysts in organic synthesis, hydrogen evolution, CO2 reduction, and degradation of organic pollutants.

Transformation of CO2 into valuable chemicals and especially fuels is deemed as a promising approach to reduce our dependence on fossil fuels and to alleviate climate change. Carbazole-based porous polymers bearing rhenium-metalated polypyridine functionalities were constructed via simple oxidative coupling reaction. These porous polymers are employed as heterogeneous supports for immobilization of catalytically active rhenium complexes and furthermore provide high CO2 adsorption capabilities and light absorption abilities, i.e., photosensitizing properties. Consequently, such rhenium-metalated microporous polycarbazole networks show high efficiencies for CO2 photoreduction upon visible-light irradiation, with a CO evolution rate up to 623 μmol g–1 h–1 and selectivity of 97.8%. The microporous solid photocatalyst shows enhanced stability and photocatalytic performance compared to the molecular catalysts during long-term use.

Photoredox catalysis has aroused great interest from chemists, as it offers a powerful tool for organic synthesis. Cationic polycarbazole networks (CPOP-28 and CPOP-29) were prepared via simple oxidative coupling reaction and applied as heterogeneous photocatalysts for a wide range of oxidative organic transformations, including oxidation of sulfides, hydroxylation of arylboronic acids, and crossdehydrogenative coupling reactions, in the presence of visible light and air. Remarkably, photocatalytic activities are enhanced by ingenious introduction of trifluoromethyl groups to the polymeric network CPOP-29. The effects of the trifluoromethyl group on photocatalytic activities were elucidated in terms of photophysical and electrochemical properties. The appealing photocatalytic performance of the trifluoromethylated polymer is ascribed to superior light-absorption ability, longer fluorescence lifetime, and stronger oxidative capability. In addition, the photocatalysts showed good recyclability and could be reused after a simple separation workup.