Enhancing interfacial charge transfer efficiency via π-π interaction in PTA/VC-CN S-scheme heterojunction for efficient photocatalytic CO2 conversion

Carbon nitride (CN) has received extensive interest due to their good stability and unique conjugated structures. However, the weak charge separation ability and poor active sites lead to undesirable photocatalytic CO 2 reduction activity. Here, we successfully prepare all-organic PTA/V C -CN S-scheme heterojunction photocatalysts by integrating CN with carbon vacancies (V C -CN) and perylene tetracarboxylic acid (PTA) for photocatalytic CO 2 reduction. The introduced carbon vacancies can act as electron trapping sites, break the symmetry structure of CN and facilitate in-plane photogenerated carrier separation and transfer of CN, while the coupling of PTA with V C -CN via π-π interaction to form a built-in electric field further speeds up the interfacial charge transfer, thereby collectively enhancing the separation and transfer efficiencies of photogenerated carriers. Moreover, the high reduction capability of V C -CN with carbon vacancies as possible active sites and wide-spectrum light absorption of PTA render the S-scheme heterojunction with high photocatalytic activity. The optimum PTA/V C -CN photocatalyst exhibits a high CO production rate of 47.91 μmol g −1  h −1 , which is about 10.7 and 4.2 times higher compared to those of CN and V C -CN, respectively. This work provides a new strategy for developing all-organic CN-based S-scheme heterojunction photocatalysts used in CO 2 conversion.