Na/K co-doped crystalline carbon nitride nanorods with nitrogen defects for photocatalytic biorefineries and H2 production

In this work, sodium (Na) and potassium (K) co-doped crystalline carbon nitride nanorods with poly(heptazine imide) framework (NaKPHI), characterized by elevated in-plane crystallinity and nitrogen defects, were constructed and synthesized. The morphology, in-plane crystallinity and sodium doping content of the catalyst can be adjusted by the calcination temperature and sodium chloride amounts. The optimal Na1KPHI exhibits excellent photocatalytic activity for water splitting coupled with glucose conversion, co-producing hydrogen (4.11 mmol g-1 h-1) and lactic acid (71.2 %) 16.4 times higher than bulk carbon nitride. Compared with monometal-doped samples, the dual-metal-doped catalyst generates more center dot OH radicals, enhancing the selective oxidation of glucose to lactic acid. The co-doped K and Na ions and the introduced nitrogen defects create charge transfer paths between layers and planes, thereby accelerating the migration of photoinduced carriers. This work presents a reliable approach for the rational design and manufacturing of triple-strategy modified crystalline carbon nitride, aiming to generate sustainable energy and products by incorporating biomass photorefineries.