Enhanced Photocatalytic Degradation of Tetracycline by Agl/BiVO4 Heterojunction under Visible-Light Irradiation: Mineralization Efficiency and Mechanism
Enhanced Photocatalytic Degradation of Tetracycline by Agl/BiVO4 Heterojunction under Visible-Light Irradiation: Mineralization Efficiency and Mechanism
复制标题
可见光照射下 Agl/BiVO4 异质结增强光催化降解四环素：矿化效率和机制
DOI：
10.1021/acsami.6b12278
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发表时间：
2016-12-07
影响因子：
9.5
通讯作者：
Zeng, Guangming
中科院分区：
文献类型：
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作者：
Chen, Fei;Yang, Qi;Zeng, Guangming
近年来，可见光驱动光催化技术在环境污染物修复中受到了极大的关注。本研究采用原位沉淀法合成了新型异质结构光催化剂AgI/BiVO4。AgI/BiVO4异质结在可见光照射下对难降解的污染物(四环素，一种典型的抗生素)表现出良好的光催化活性。AgI：BiVO4质量比为1：4的合成样品具有最高的光催化性能。TC分子在60min内基本被去除(94.91%)，且在相同条件下的降解效率明显高于裸BiVO4(62.68%)和AgI(75.43%)。同时，TOC在120min内也达到了90.46%的去除效果，说明矿化效果更好，三维激发发射矩阵荧光光谱(3DEMS)进一步证实了这一点。X射线衍射仪、X射线光电子能谱、差示扫描量热仪和荧光光谱测试表明，在光降解的早期阶段就有少量的银纳米粒子生成。AgI/BiVO4(双重型)向AgI/Ag/BiVO4(三明治状)的结构转变提高了相应的可见光吸收性能。由AgI、Ag和BiVO4组成的自组装Z型异质结也有效地促进了光生电子空穴对的分离，最终提高了TC的降解效率。在活性物种捕获实验和ESR分析的基础上，对光催化机理进行了详细的讨论，实验结果证实了超氧阴离子自由基和空穴在光催化过程中起着至关重要的作用。此外，连续四次循环后，TC的降解效率没有明显下降，说明AgI/BiVO4纳米复合材料具有良好的光稳定性。这些特性表明AgI/BiVO4异质结在去除废水中的难降解污染物方面具有很大的应用潜力。
Recently, visible-light-driven photocatalysis is of great interest in the environmental pollutant remediation. In the present study, a novel heterostructured photocatalyst AgI/BiVO4 was synthesized by an in situ precipitation procedure. The AgI/BiVO4 heterojunctions exhibited excellent photoactivity for the refractory pollutant (tetracycline (TC), a typical antibiotic) decomposition under visible light illumination. The synthetic sample with 1:4 mass ratio of AgI:BiVO4 possessed the highest photocatalytic performance in all of the as-prepared catalysts. The TC molecules were substantially eliminated (94.91%) within 60 min, and degradation efficiency was considerably better than those of bare BiVO4 (62.68%) and AgI (75.43%) under identical conditions. Simultaneously, 90.46% of TOC removal was also achieved within 120 min, suggesting that the mineralization was superior and further confirmed by three-dimensional excitation emission matrix fluorescence spectroscopy (3D EEMs). The XRD, XPS, DRS, and PL measurements revealed that a small amount of Ag nanoparticles was produced at the early photodegradation process. The structure transformation from AgI/BiVO4 (double-type) to AgI/Ag/BiVO4 (sandwich-like) improved the corresponding visible-light absorption performance. The self-assembly Z-scheme heterojunction that consisted of AgI, Ag, and BiVO4 also efficiently accelerated photoinduced electron hole pairs' separation and ultimately improved the efficiency of TC degradation. The responsible photocatalytic mechanism was discussed in detail on the basis of the reactive species capturing tests and ESR analysis, and the experimental results had been validated that superoxide radicals and holes played a vital role during the photocatalytic process. Furthermore, TC degradation efficiency was not of significant loss after four consecutive cycles, suggesting the excellent photostability of AgI/BiVO4 nanocomposite. These features demonstrate that the AgI/BiVO4 heterojunction has great application potential for refractory pollutants' removal from wastewater.