Co-porphyrin/carbon nitride hybrids for improved photocatalytic CO2 reduction under visible light

A covalently linked reaction center/antenna hybrid composed of Co-porphyrin and low-molecular-weight carbon nitride was developed for the reduction of CO2 into CO under visible light for the first time. The hybrids possessed thirteen-fold higher photocatalytic activity (17 μmol/g/h) compared with bulk carbon nitride, and it is more than twice what it was in the Co-porphyrin loaded C3N4 heterojunction system. The efficient electron transfer and trapping by the Co active sites as well as the affinity of Co-porphyrin for CO2 are considered to account for the enhanced activity. Our findings may open a promising route to modify carbon nitride and provide a feasible approach to immobilize the active site into the light-harvest antenna for efficient electron-hole separation, electron transferring and the following redox reaction in photocatalytic process, which reforms the conventional semiconductor-cocatalyst heterojunction system.