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.