In this study, a Z-scheme heterojunction photocatalyst was successfully synthesized via a hydrothermal approach by coupling protonated g-C 3 N 4 derived from hydrochloric acid modification with the solid solution BiOI 0.8 Br 0.2 . The as-prepared material was systematically characterized using XRD, FT-IR, SEM, HRTEM, XPS, PL, and photoelectrochemical measurements to evaluate its crystalline structure, surface morphology, elemental chemical states, defect features, and optical as well as photoelectrochemical properties. HRTEM analysis revealed a nanoflower-like architecture in which ultrathin g-C 3 N 4 nanosheets were uniformly anchored onto the surface of BiOI 0.8 Br 0.2 nanoflowers, facilitating intimate interfacial contact between the two components. Electrochemical impedance spectroscopy and transient photocurrent response measurements demonstrated a marked reduction in interfacial resistance and a significant increase in current density, indicating enhanced charge transfer efficiency at the heterojunction interface and promoting effective separation and rapid migration of photogenerated electron–hole pairs. Under the Z-scheme charge transfer mechanism, electrons from the conduction band of BiOI 0.8 Br 0.2 recombine with holes from the valence band of g-C 3 N 4 at the interface, thereby preserving highly reductive electrons in the g-C 3 N₄ component and highly oxidative holes in BiOI 0.8 Br 0.2 . This spatial charge separation significantly enhances the redox capability of the system. Consequently, the resulting photocatalyst exhibited outstanding degradation performance toward RhB and ENR under light irradiation, with high efficiency and excellent stability. Furthermore, recycling experiments confirmed that the catalyst retained high activity and structural integrity over multiple cycles, underscoring its robustness and potential for practical applications in environmental remediation.
Zhang et al. (Tue,) studied this question.