铁酸铋系化合物BiFeO₃和Bi₂Fe₄O₉因其结构和稳定性优势成为光催化材料的研究热点. 本工作采用溶胶-凝胶法制备了Ag掺杂BiFeO₃和Bi₂Fe₄O₉粉末, 研究了其在紫外光下对罗丹明B (RhB)溶液的光催化降解性能. 结果表明, 适量掺杂Ag (3 mol%)的Bi₂Fe₄O₉显示出优异的光催化性能, 对RhB的降解率高达96%. 然而, 对BiFeO₃而言, 掺杂Ag元素后会出现杂相Bi₂Fe₄O₉和Bi₂₅FeO₄₀, 样品的光催化性能未表现出显著提升, 其降解率仅为50%. 通过紫外-可见漫反射光谱分析发现, Bi₂Fe₄O₉具有双带隙特征, 分别为1.28 eV和1.36 eV. 结合密度泛函理论(DFT)计算得知, Ag 4d轨道在Bi₂Fe₄O₉的价带顶附近引入了缺陷能级, 有效缩小了带隙, 从而显著提高了光催化效率. 荧光光谱数据也进一步证明, Ag掺杂有效抑制了光生载流子的复合, 提高了光催化性能. 本研究为铁酸铋系化合物在光催化领域的应用与开发提供了一条可行的技术路径.

Bismuth ferrite-based compounds, such as BiFeO₃ and Bi₂Fe₄O₉, have attracted significant attention as photocatalytic materials due to their favorable structural properties and stability. In this study, Ag-doped BiFeO₃ and Bi₂Fe₄O₉ powders were synthesized using the sol-gel method, and their photocatalytic properties were evaluated through the degradation of Rhodamine B (RhB) under ultraviolet (UV) light. The results showed that Ag doping notably enhanced the photocatalytic properties of Bi₂Fe₄O₉. Specifically, 3 mol% Ag-doped Bi₂Fe₄O₉ exhibited an impressive RhB degradation rate of 96%, indicating its high efficiency for photocatalytic applications. In contrast, Ag doping in BiFeO₃ led to the formation of mixed phases, including Bi₂Fe₄O₉ and Bi₂₅FeO₄₀, and resulted in only a modest improvement in photocatalytic performance, with a RhB degradation rate of 50%. These findings highlight the superior photocatalytic activity of Bi₂Fe₄O₉ compared to BiFeO₃, emphasizing the importance of material composition and doping concentration in optimizing photocatalytic efficiency. Moreover, UV-Vis diffuse reflectance spectroscopy was used to investigate the electronic properties of the materials. The analysis revealed that Bi₂Fe₄O₉ exhibits a dual-bandgap feature with values of 1.28 eV and 1.36 eV, which enhances the material's ability to absorb visible light and improves its photocatalytic performance under ambient light conditions. To explore the mechanisms behind these improvements, density functional theory (DFT) calculations were conducted. The results indicate that the Ag 4d orbitals introduce defect energy levels near the valence band maximum of Bi₂Fe₄O₉, effectively narrowing the bandgap. This facilitates more efficient charge separation, which is crucial for enhancing photocatalytic properties. Fluorescence spectroscopy further confirmed that Ag doping effectively inhibits the recombination of photogenerated electron-hole pairs, further boosting the photocatalytic efficiency of Bi₂Fe₄O₉. This study provides valuable insights into the potential of Ag-doped bismuth ferrite-based compounds for advanced photocatalysis, and pave the way for the development of efficient photocatalysts for environmental and energy-related applications, such as water purification and solar energy conversion.