Rational Design of Methylated Triazine-Based Linear Conjugated Polymers for Efficient CO₂ Photoreduction with Water

The development of semiconducting conjugated polymers for photoredox catalysis holds great promise for sustainable utilization of solar energy. Herein a new family of porous methylated triazine-based linear conjugated polymers is reported that enable efficient photoreduction of carbon dioxide (CO₂) with water (H₂O) vapor, in the absence of any additional photosensitizer, sacrificial agents or cocatalysts. It is demonstrated that the key lies in the generation of methylated triazine linkages through a facile condensation reaction between benzamidine and acetic anhydride, which impedes the formation of conventional triazine-based frameworks. It is also shown that regulating conjugated linear backbones with different lengths of electron-donated benzyl units provides a facile means to modulate their optical properties and the exciton dissociation, thereby affording more long-lived photogenerated charge carriers and boosting charge separation and transfer. A high-performance carbon monoxide (CO) production rate of 218.9 µmol g^-1 h^-1 is achieved with ≈ 100% CO selectivity, which is accompanied by exceptional H₂O oxidation to oxygen (O₂). It anticipates this new study will advance synthetic approaches toward polymeric semiconductors and facilitate new possibilities for triazine-based conjugated polymers with promising potential in artificial photocatalysis.