In-situ one-step construction of poly(heptazine imide)/poly(triazine imide) heterojunctions for photocatalytic hydrogen evolution.

The construction of heterojunctions is challenging, requiring atomic-level contact and interface matching. Here, we have achieved atomic-level interfacial matching by constructing poly(heptazine imide)/poly(triazine imide) crystalline carbon nitride heterojunctions in an in-situ one-step method. The content of poly(triazine imide) in heterojunctions is positively related to the proportion of lithium chloride in potassium chloride and lithium chloride mixed-salts. The optimized heterojunction achieves an apparent quantum efficiency of 48.34 % for photocatalytic hydrogen production at 420 nm, which is at a good level in polymeric carbon nitride photocatalysts. The proposed ion-thermal assisted heterojunction construction strategy contributes to the development of polymeric carbon nitride photocatalysts with high crystallization and high charge separation efficiency.