ABSTRACT

Novel magnetically separable BiOBr/BiFeO₃ heterostructures were fabricated via a facile in situ hydrothermal chemical etching process using cetyltrimethyl-ammonium bromide (CTAB) and sulphuric acid as etching agents to react with BiFeO₃ particles. The effects of solution pH and CTAB amount on the structure, morphology, and optical properties of the as-prepared samples were investigated. It was found that the best acidity of solution is pH = 3.0 for the formation of BiOBr/BiFeO₃ heterostructures from BiFeO₃ powder. Their photocatalytic activities and anti-photocorrosion behaviour were measured by the photocatalytical reduction of heavy metal ion Cr (VI) under visible-light irradiation. Experimental results show that the molar ratio of BiOBr to BiFeO₃ contributed to different morphologies and photocatalytic activities of BiOBr/BiFeO₃ composites. The optimised molar ratio in BiOBr/BiFeO₃ composites was found to be 1:1. The photocatalytic reduction rate of Cr(VI) over 1:1 BiOBr/BiFeO₃ composites was found to be 4.9 and 3.0 times higher than that of pure BiFeO₃ and BiOBr, respectively. The hybridisation of BiOBr with BiFeO₃ can markedly inhibit the photocorrosion of semiconductor BiFeO₃. No obvious catalytic activity decrement can be found after five consecutive photocatalytic Cr (VI) reduction, which demonstrates the high structural stability of 1:1 BiOBr/BiFeO₃. Furthermore, a possible photogenerated charge transfer process was proposed. The obviously enhanced photocatalytic activity could be ascribed to the formation of BiOBr-BiFeO₃ heterojunction, accelerating the effective separation of photoexcited electron−hole pairs. This study suggests that the magnetically separable BiOBr/BiFeO₃ heterostructures can be a promising photocatalyst for environment-related applications.

摘要

使用十六烷基三甲基溴化铵 (CTAB) 和硫酸作为蚀刻剂与 BiFeO ₃颗粒反应，通过简便的原位水热化学蚀刻工艺制备了新型可磁分离的 BiOBr/BiFeO ₃异质结构。研究了溶液 pH 值和 CTAB 用量对所制备样品的结构、形貌和光学性质的影响。_{研究发现，从 BiFeO 3形成 BiOBr/BiFeO 3}异质结构的最佳溶液酸度是 pH = 3.0粉末。通过可见光照射下重金属离子Cr(VI)的光催化还原来测量它们的光催化活性和抗光腐蚀行为。实验结果表明，BiOBr与BiFeO 3 的摩尔比对_BiOBr /BiFeO ₃复合材料的不同形态和光催化活性有影响。BiOBr/BiFeO ₃复合材料的优化摩尔比为 1:1。_{发现 Cr(VI) 在 1:1 BiOBr/BiFeO 3}复合材料上的光催化还原率分别是纯 BiFeO ₃和 BiOBr的 4.9 倍和 3.0 倍。BiOBr与BiFeO ₃的杂化可以显着抑制半导体BiFeO的光腐蚀₃ . 连续5次光催化Cr(VI)还原后催化活性没有明显下降，这表明1:1 BiOBr/BiFeO ₃具有较高的结构稳定性。此外，还提出了一种可能的光生电荷转移过程。明显增强的光催化活性可归因于BiOBr-BiFeO ₃异质结的形成，加速了光激发电子-空穴对的有效分离。该研究表明，可磁分离的BiOBr/BiFeO ₃异质结构可能是一种用于环境相关应用的有前途的光催化剂。