Boosting CO₂ photoreduction by creating electron mediator in carbon‐enriched poly(heptazine imide)

The insufficient light absorption capacity and severe photogenerated carrier recombination limit the overall efficiency of photocatalysts. Herein, we designed carbon‐rich poly(heptazine imide) (PHI) by copolymerization of melamine and 2,4,6‐triamine‐pyrimidine with KCl/KI. This material has been demonstrated to markedly enhance the utilization rate of photons while simultaneously optimizing the charge efficiency of photogenerated electrons. The carbon‐rich PHI showed a higher CO₂ reduction efficiency than the PHI, with a CO generation rate reaching 46.6 μmol g⁻¹ h⁻¹. To overcome the obstacle of slow mass transfer, a flow reactor was designed in‐house. The CO yield on carbon‐rich PHI in the home‐built flow reactor was found to be as high as 153 μmol g⁻¹ h⁻¹, which is 3.3 times that observed in the batch reactor. The findings of the experimental study are in alignment with the results of the theoretical modeling, which was based on the finite volume analysis method.