Scalable electropolymerized microporous polymer films for solar light-driven reduction of atmospheric CO₂ coupled with H₂O₂ production

Large-area flexible polymer films with permanent porosity and appealing electronic properties are highly desirable for photocatalytic CO₂ conversion. However, controllable manufacturing of polymer-based photocatalytic films for selective CO₂ reduction remains challenging and is rarely explored. Herein, scalable microporous polymer films are rapidly prepared via facile electropolymerization for photocatalytic reduction of atmospheric CO₂ coupled with H₂O₂ production. The N-functionalized pores enable poly(9′-phenyl-9′H-9,3′:6′,9″-tercarbazole) (PPTC) and poly(2,6-bis(9H-carbazol-9-yl)pyridine) (PBCP) to achieve high CO₂/N₂ selectivity (69–81 at 298 K) and provide abundant sites for CO₂ and O₂ activation under light irradiation. Owing to intramolecular donor–acceptor interactions between pyridine and carbazole units, the PBCP film exhibits a reduced optical gap of 2.01 eV and substantially boosts photoinduced charge transfer compared with the PPTC film. Consequently, under solar light (100 mW cm⁻²), the metal-free PBCP film (8.54 µm-thick film) in air and pure water delivers excellent CO and H₂O₂ yields of 741.38 and 1352.33 μmol h⁻¹ g⁻¹, respectively, surpassing those reported for other photocatalysts under similar conditions. This study demonstrates a rapid fabrication route for polymer films, enabling efficient atmospheric CO₂ reduction and simultaneous H₂O₂ production under solar light.