Enabling sustainable bifunctional photocatalytic synthesis by boosted defective carbon nitride with frustrated Lewis pairs

Developing efficient photocatalytic platforms for CO 2 conversion and H 2 O 2 production continues to be a significant challenge. Despite being a well-known promising metal-free photocatalyst, ineffective charge separation and a scarcity of active sites prevent graphitic carbon nitride (g-C 3 N 4 ) from being used in practice. We describe herein a one-step synthesis method to create B-K co-doped g-C 3 N 4 with surface hydroxyl groups and nitrogen vacancies at low temperature. This engineered material displays remarkable dual-function catalytic activity. It produces 85% styrene carbonate (25 mmol g -1 h -1 ) in photocatalytic CO 2 cycloaddition at ambient temperature and a high H 2 O 2 formation rate of 9633 μmol g -1 h -1 . The improved performance stems from synergistic effects among the structural sites. Potassium doping creates Lewis acid sites and encourages electron delocalization. The most important design characteristic is that frustrated Lewis pairs (FLPs) developed between the boron centers and the carbon atoms that are next to nitrogen vacancies. The FLPs induce a concerted electron “push-pull” interaction that facilitates the concurrent activation of CO 2 . Furthermore, the nitrogen vacancies and cyano groups act in concert to open a channel for efficient electron transfer, markedly improving charge separation. Surface hydroxyl groups directly accelerate the reaction kinetics by facilitating proton transfer. This work establishes a design principle for bifunctional photocatalysts based on the synergistic creation of active sites, providing a rational strategy for their integration.