Covalent Microporous Polymer Nanosheets for Efficient Photocatalytic CO₂ Conversion with H₂ O

It is still a challenging target to achieve photocatalytic CO₂ conversion to valuable chemicals with H₂ O as an electron donor. Herein, 2D imide-based covalent organic polymer nanosheets (CoPcPDA-CMP NSs), which integrate cobalt phthalocyanine (CoPc) moiety for reduction half-reaction and 3,4,9,10-perylenetetracarboxylic diimide moiety for oxidation half-reaction, are constructed as a Z-scheme artificial photosynthesis system to complete the overall CO₂ reduction reaction. Owing to the outstanding light absorption capacity, charge separation efficiency, and electronic conductivity, CoPcPDA-CMP NSs exhibit excellent photocatalytic activity to reduce CO₂ to CO using H₂ O as a sacrificial agent with a CO production rate of 14.27 µmol g^-1 h^-1 and a CO selectivity of 92%, which is competitive to the state-of-the-art visible-light-driven organic photocatalysts towards the overall CO₂ reduction reaction. According to a series of spectroscopy experiments, the authors also verify the photoexcited electron transfer processes in the CoPcPDA-CMP NSs photocatalytic system, confirming the Z-scheme photocatalytic mechanism. The present results should be helpful for fabricating high-performance organic photocatalysts for CO₂ conversion.