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

Abstract Photocatalytic technology based on polymeric carbon nitride (PCN) offers a sustainable and ecofriendly approach to hydrogen peroxide (H 2 O 2 ) 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% NaNO 3 –40% KNO 3 ) 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 H 2 O 2 artificial photosynthesis through two‐step single‐electron oxygen reduction reaction pathways, and achieves an impressive H 2 O 2 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 H 2 O 2 artificial photosynthesis.