Luo Linbo, Dong Sheying, Cui Hao, Sun Longhui, Huang Tinglin
School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China.
School of Chemistry and Chemical Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China; School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China.
J Colloid Interface Sci. 2022 Jan 15;606(Pt 2):1299-1310. doi: 10.1016/j.jcis.2021.08.111. Epub 2021 Aug 18.
The ecosystems and human health were seriously threatened by hexavalent chromium (Cr(VI)) in wastewater. In this article, using the idea of the highly matched energy band structure between indium sulfide (InS) and MIL-53(Fe), a Type-II heterojunction has been constructed by loading InS on MIL-53(Fe) microrod to overcome the fault like high recombination rates of photogenerated electron-holes of InS. The composite with 20:1 mass ratio of InS to MIL-53(Fe) (IM-2) was adopted as an optimal sample for efficient photocatalytic Cr(VI) reduction under visible light. Various characterization techniques were used to verify the characteristics of composites and delved into the structure-effect relationship between this heterojunction and its activity. Results showed that the reaction rate constants of the photoreduction process over IM-2 was ~ 4 and 26 times higher than those of pure InS and MIL-53(Fe), respectively, and the catalyst could maintain superior removal efficiency (88.6%) and steady crystal structure after four cycles. First-principles calculations further illustrated that the heterostructure formed between InS and MIL-53(Fe) could effectively accelerate the separation of photogenerated electrons and holes, thus improving the photocatalytic reduction performance. Moreover, the active species analyses revealed that the superoxide radicals and electrons were mainly involved in the reduction of Cr(VI).
废水中的六价铬（Cr(VI)）严重威胁着生态系统和人类健康。在本文中，利用硫化铟（InS）与MIL-53(Fe)之间高度匹配的能带结构这一理念，通过将InS负载在MIL-53(Fe)微棒上构建了II型异质结，以克服InS光生电子-空穴复合率高的缺陷。采用InS与MIL-53(Fe)质量比为20:1的复合材料（IM-2）作为最佳样品，用于可见光下高效光催化还原Cr(VI)。使用各种表征技术来验证复合材料的特性，并深入研究这种异质结与其活性之间的构效关系。结果表明，IM-2上光还原过程的反应速率常数分别比纯InS和MIL-53(Fe)高约4倍和26倍，并且该催化剂在四个循环后仍能保持优异的去除效率（88.6%）和稳定的晶体结构。第一性原理计算进一步表明，InS与MIL-53(Fe)之间形成的异质结构可以有效地加速光生电子和空穴的分离，从而提高光催化还原性能。此外，活性物种分析表明，超氧自由基和电子主要参与了Cr(VI)的还原过程。
