A Low‐Temperature Solar Salt Approach to Fabricate Crystalline Polymeric Carbon Nitride for H ₂ O ₂ Efficient Photosynthesis

Photocatalytic technology based on polymeric carbon nitride (PCN) offers a sustainable and ecofriendly approach to hydrogen peroxide (H₂O₂) production field. Nonetheless, the effectiveness of PCN is significantly hindered by the strong binding energy of excitons and slow transfer ability of carriers. Herein, SS-UPCN-375 photocatalyst is prepared by one-pot solar salt (60% NaNO₃-40% KNO₃) thermal polymerization at 375 °C for the first time using nitrogen-rich precursors. The use of solar salt as a thermal reaction medium facilitates rapid control of the crystallization process and the electronic structure of photocatalysts, and yielding SS-UPCN-375 characterized by high crystallinity, augmented visible light utilization, and efficient exciton dissociation capability. Most importantly, SS-UPCN-375 demonstrates outstanding H₂O₂ artificial photosynthesis through two-step single-electron oxygen reduction reaction pathways, and achieves an impressive H₂O₂ production rate of 1.80 mmol L^-1 h^-1, which is almost 6.7 times superior to that of pristine UPCN. In short, a novel approach that employs solar salt as a low-temperature solvent to specifically tailor the grain boundary structure and chemical composition of PCN is presented, and it further offers essential guidance for designing high-performance PCN-based photocatalysts to promote H₂O₂ artificial photosynthesis.