Poly(heptazine-triazine) Imide Carbon Nitride with Tunable n→π* Electronic Transition for Efficient Solar H2S Decontamination

Stimulating electronic transitions and promoting exciton dissociation are key to enhancing the photocatalytic performance of polymer carbon nitride (PCN). Herein, a controllable synthesis strategy based on supramolecular self-assembly and mild salt melting crystallization has been developed, successfully preparing carbon nitride-based photocatalytic materials with tunable crystal phase composition. The mixed crystal phases effectively induced significant n→π* electronic transition, expanding the material’s light response range to the near-infrared region (700 nm). Meanwhile, the homojunction promoted the efficient separation of photogenerated carriers through the built-in electric field. Under visible-light excitation, this material exhibits excellent selective catalytic performance, over 99% for the oxidation and removal of H2S into elemental sulfur. This synergistic mechanism of crystal phase engineering in regulating electronic structure and interface charge dynamics provides a new material design strategy for efficient non-metallic photocatalysts.