Ferroelectric polarization significantly enhances the photocatalytic performance of Bi2Fe4O9/RGO/nitrogen-deficient g-C3N4 Z-scheme heterojunction

Abstract

Semiconductor photocatalysis is a method for degrading pollutants using sunlight, has been widely recognized as an ideal approach for treating organic pollutant wastewater due to its low cost, high efficiency, and environmental friendliness. However, efficiently separating and transferring photogenerated electron-hole pairs remains a major challenge in designing effective photocatalysts. In this study, we designed a Bi₂Fe₄O₉/RGO/nitrogen-deficient g-C₃N₄ (BGC) catalyst and investigated the photocatalytic degradation of methylene blue (MB). The results showed that the BGC heterojunction exhibited superior photocatalytic activity compared to both pure g-C₃N₄ and Bi₂Fe₄O₉/RGO (BGO). The introduction of ferroelectric polarization further enhanced the separation efficiency of photogenerated carriers in BGCp, significantly improving the MB degradation efficiency. KPFM analysis revealed that the surface potential of BGCp-15 reached 115.2 mV, which is 2.07 times that of the non-polarized sample. The degradation rate constant for BGCp-15 was measured as 0.06076 min⁻¹ , representing a 40 % increase compared to the unpolarized BGC-15 sample. The enhanced performance of the Bi₂Fe₄O₉/RGO/nitrogen-deficient g-C₃N₄ can be attributed to the synergistic effects of nitrogen defects, Z-scheme heterojunctions, and ferroelectric polarization. Specifically, spontaneous polarization in ferroelectric materials promoted anisotropic charge separation, suggesting that ferroelectric regulation is a promising strategy for enhancing electron-hole separation in photocatalytic semiconductor systems. This study provides both theoretical and experimental support for developing efficient photocatalysts through modification, heterojunction construction, and ferroelectric regulation.