Pyrene-functionalized polymeric carbon nitride with promoted aqueous-organic biphasic photocatalytic CO₂ reduction

We have demonstrated a simple copolymerization process to covalently graft pyrene-functional groups on the polymeric carbon nitride (PCN) surface. The resulting pyrene functionalized carbon nitride (Py-PCN) exhibits unique biphasic photocatalytic activities, which enable efficient CO₂ photoreduction in aqueous solution with simultaneous alkene (C═C) oxidation in the organic phase. The great biphasic activities are attributed to the increased lipophilicity from surface pyrene-functional groups, which allows the hydrophobic alkene molecules to readily approach the PCN surface and react with the hydroxyl radicals created from-OH oxidation by photogenerated holes. In this way, the alkene compounds indirectly consume the photo-holes from excited Py-PCN, promoting the overall photocatalytic process. Our study provides a new strategy for solar fuel production with simultaneous organic synthesis by the oxidation power of photo-holes on amphiphilic metal-free semiconductors.