Nitrogen vacancies contained all-organic g-C₃N₄/tetra (4-carboxylphenyl) porphyrin heterojunction formed with π-π interactions for efficient visible light photocatalytic performance

Defect engineering and heterojunction formation are essential for modifying photocatalysts to improve the separation efficiency of photogenerated carriers. In this work, an all-organic π-π interaction-based novel heterojunction (NVCN/TCPP), that combines nitrogen vacancies enriched-g-C₃N₄ and tetra (4-carboxylphenyl) porphyrin (TCPP) was synthesized. Scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR/TEM), X-ray diffraction (XRD), Fourier Transform-Infrared (FT-IR) spectroscopy, Brunauer-Emmett-Teller (BET) test, and X-ray photoelectron spectroscopy (XPS) were used to investigate the surface morphology, micromorphology, crystal structure, and functional groups in the samples. Both NVCN and TCPP had a two-dimensional nanosheet morphology. The electron paramagnetic resonance (EPR) results confirmed the existence of nitrogen vacancies in graphitic carbon nitride (g-C₃N₄). The photocatalytic performance of the composites was evaluated by the degradation of Rhodamine B (RhB) under visible light. NVCN/TCPP-1 showed the best photocatalytic performance, which was attributed to the synergistic effect of nitrogen vacancies and TCPP present in the composite that facilitated the separation and transfer of photogenerated carriers. We conducted a thorough investigation into the mechanism for enhanced photocatalysis and presented a Z-scheme heterojunction mechanism to explain our findings. This study could serve as a valuable reference for the construction of organic heterojunctions.