Enhanced Charge Separation Endowed by Perylene Diimide Polymers Decorated N Vacancy on Carbon Nitride S‐Scheme Heterojunction for Efficient Photocatalytic N₂ Fixation

Designing effective photocatalyst with high charge carrier utilization for photocatalytic N 2 fixation is extremely crucial but remains a challenge. Hence, a novel p ‐phenylenediamine substituted perylenediimide (pPDI)/nitrogen vacancy‐modified carbon nitride (NV–CN) S‐scheme heterojunction photocatalyst, integrated with pPDI polymers and NV–CN, is synthesized. The introduction of bridged p ‐phenylenediamine units in the pPDI skeleton creates a strong built‐in electric field, which can significantly enhance the separation and migration of charge. Additionally, the constructed S‐scheme system greatly facilitates the interfacial photogenerated carrier separation and transfer. Meanwhile, the introduction of nitrogen vacancies into NV–CN acts as an electron trap to capture electrons, thus preventing the recombination of electron–hole pairs and significantly prolongs N 2 absorption capacity. Benefiting from these synergistic advantages, the optimized 10% pPDI/NV–CN heterojunction achieves a superior NH 3 yield of 8.83 m M g −1 h −1 , achieving 12.26 and 13.63 times increase over CN (0.72 m M g −1 h −1 ) and PDI (0.65 m M g −1 h −1 ), respectively. This article provides an innovative perspective for the synthesis of CN‐based photocatalysts for the efficient N 2 reduction through the introduction of bridging p ‐phenylenediamine units, nitrogen vacancy modification, and the construction of S‐scheme heterojunctions.