College of Environmental Science and Engineering, and ‡Key Laboratory of Environmental Biology and Pollution Control, Ministry of Education, Hunan University , Changsha 410082, People's Republic of China.
ACS Appl Mater Interfaces. 2016 Dec 7;8(48):32887-32900. doi: 10.1021/acsami.6b12278. Epub 2016 Nov 29.
Recently, visible-light-driven photocatalysis is of great interest in the environmental pollutant remediation. In the present study, a novel heterostructured photocatalyst AgI/BiVO was synthesized by an in situ precipitation procedure. The AgI/BiVO 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:BiVO 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 BiVO (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/BiVO (double-type) to AgI/Ag/BiVO (sandwich-like) improved the corresponding visible-light absorption performance. The self-assembly Z-scheme heterojunction that consisted of AgI, Ag, and BiVO 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/BiVO nanocomposite. These features demonstrate that the AgI/BiVO heterojunction has great application potential for refractory pollutants' removal from wastewater.
最近，可见光驱动的光催化在环境污染物修复中引起了极大的兴趣。在本研究中，通过原位沉淀法合成了一种新型的异质结构光催化剂 AgI/BiVO。AgI/BiVO 异质结在可见光照射下对难处理污染物（四环素（TC），一种典型的抗生素）的分解表现出优异的光活性。在所有制备的催化剂中，AgI:BiVO 质量比为 1:4 的合成样品表现出最高的光催化性能。在 60 分钟内，TC 分子被大量消除（94.91%），在相同条件下，其降解效率明显优于纯 BiVO（62.68%）和 AgI（75.43%）。同时，在 120 分钟内也实现了 90.46%的 TOC 去除，这表明矿化作用更好，并通过三维激发发射矩阵荧光光谱（3D EEMs）进一步证实。XRD、XPS、DRS 和 PL 测量表明，在早期光降解过程中产生了少量的 Ag 纳米粒子。AgI/BiVO（双型）向 AgI/Ag/BiVO（夹层型）的结构转变提高了相应的可见光吸收性能。由 AgI、Ag 和 BiVO 组成的自组装 Z 型异质结也有效地加速了光生电子空穴对的分离，最终提高了 TC 降解的效率。基于活性物种捕获试验和 ESR 分析，详细讨论了负责的光催化机制，实验结果表明，在光催化过程中，超氧自由基和空穴起着至关重要的作用。此外，AgI/BiVO 纳米复合材料在连续四次循环后，TC 降解效率没有明显损失，表明其具有优异的光稳定性。这些特点表明，AgI/BiVO 异质结在废水处理中去除难处理污染物具有巨大的应用潜力。
