Unveiling the Synergistic Role of Ferroelectric Polarization and Z‐Scheme Heterojunction in Bi₂Fe₄O₉/Carbon‐Deficient g‐C₃N₄ for Enhanced Methylene Blue Degradation Efficiency

ABSTRACT Enhancing the efficiency of charge carrier separation is crucial for improving the performance of photocatalysts, thereby offering more effective solutions to energy and environmental pollution challenges. In this study, a carbon‐deficient ultra‐thin porous g‐C 3 N 4 (Vc‐UPCN) was synthesized and subsequently was integrated with Bi 2 Fe 4 O 9 (BFO) using a sonochemical self‐assembly technique, a Bi 2 Fe 4 O 9 /Vc‐UPCN ( BC ) photocatalyst featuring a Z‐scheme heterojunction. The BC catalyst was subjected to corona poling treatment to obtain BC p, which possesses an intrinsic electric field. Compared with pure BFO and Vc‐UPCN, the BC heterojunction exhibited higher photo‐generated electron–hole separation efficiency and photodegradation ability. Upon introduction of corona polarization, the photocatalytic performance of BC was further enhanced. Specifically, BC p‐15 (BFO/BC mass fraction = 15) achieved complete degradation of methylene blue (MB) within 30 min. BCp‐15 demonstrated that its degradation efficiency for MB was 1.28 times higher than that of BC‐15, 1.85 times higher than that of Vc‐UPCN, and impressive 7.69 times higher than that of pure BFO. The coupling effect of the heterojunction and ferroelectric polarization significantly improved the separation efficiency of photo‐generated carriers in BCp. This study is expected to provide a reference for the synergistic application of heterojunction and ferroelectric polarization in traditional semiconductor photocatalysis.