Fluorine-doped carbon nanotubes as an efficient metal-free catalyst for destruction of organic pollutants in catalytic ozonation.
Fluorine-doped carbon nanotubes as an efficient metal-free catalyst for destruction of organic pollutants in catalytic ozonation.
复制标题
DOI：
10.1016/j.chemosphere.2017.09.119
复制
发表时间：
2018
期刊：
影响因子：
8.8
通讯作者：
Jing Wang;Shuo Chen;X. Quan;Hongtao Yu
中科院分区：
文献类型：
--
作者：
Jing Wang;Shuo Chen;X. Quan;Hongtao Yu
无金属碳材料已被认为是多相催化臭氧化金属基催化剂的潜在替代品，但催化性能仍需提高。在碳中掺杂非金属杂原子（如N、B、F）可以改变原始碳材料的电子结构和电化学性能，被认为是提高碳材料催化活性的有效方法。在此，通过简单的方法合成了氟掺杂碳纳米管（F-CNT），并通过 X 射线衍射（XRD）、X 射线光电子能谱（XPS）和拉曼光谱进行了表征。合成的 F-CNT 表现出显着增强的催化臭氧化降解有机污染物的催化活性。优化后的 F-CNT 的草酸去除效率约为原始 CNT 的两倍，甚至超过了四种传统金属基催化剂（ZnO、Al2O3、Fe2O3 和 MnO2）。 XPS和拉曼研究证实，碳纳米管上的sp3C位点而不是sp2C位点形成了共价C单键F键，不仅导致与F原子相邻的C原子具有高正电荷密度，而且保留了F-CNTs完整碳结构的离域π系统，有利于臭氧分子（O3）转化为活性氧 （ROS）并有助于高草酸去除效率。此外，电子自旋共振（ESR）研究表明，超氧自由基（O2自由基点−）和单线态氧（1O2）可能是导致这些催化系统中草酸降解的主要ROS。
Metal-free carbon materials have been presented to be potential alternatives to metal-based catalysts for heterogeneous catalytic ozonation, yet the catalytic performance still needs to be enhanced. Doping carbon with non-metallic heteroatoms (e.g., N, B, and F) could alter the electronic structure and electrochemical properties of original carbon materials, has been considered to be an effective method for improving the catalytic activity of carbon materials. Herein, fluorine-doped carbon nanotubes (F-CNTs) were synthesized via a facile method and characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. The as-synthesized F-CNTs exhibited notably enhanced catalytic activity towards catalytic ozonation for the degradation of organic pollutants. The oxalic acid removal efficiency of optimized F-CNTs was approximately two times as much as that of pristine CNTs, and even exceeded those of four conventional metal-based catalysts (ZnO, Al2O3, Fe2O3, and MnO2). The XPS and Raman studies confirmed that the covalent Csingle bondF bonds were formed at the sp3C sites instead of sp2C sites on CNTs, not only resulting in high positive charge density of C atoms adjacent to F atoms, but remaining the delocalized π-system with intact carbon structure of F-CNTs, which then favored the conversion of ozone molecules (O3) into reactive oxygen species (ROS) and contributed to the high oxalic acid removal efficiency. Furthermore, electron spin resonance (ESR) studies revealed that superoxide radicals (O2radical dot−) and singlet oxygen (1O2) might be the dominant ROS that responsible for the degradation of oxalic acid in these catalytic systems.