Elucidating the Mechanistic Origin of a Spin State-Dependent FeNx-C Catalyst toward Organic Contaminant Oxidation via Peroxymonosulfate Activation.
Elucidating the Mechanistic Origin of a Spin State-Dependent FeNx-C Catalyst toward Organic Contaminant Oxidation via Peroxymonosulfate Activation.
复制标题
DOI：
10.1021/acs.est.1c05980
复制
发表时间：
2021-12
影响因子：
11.4
通讯作者：
Bofan Zhang;Xianquan Li;K. Akiyama;P. Bingham;S. Kubuki
中科院分区：
文献类型：
--
作者：
Bofan Zhang;Xianquan Li;K. Akiyama;P. Bingham;S. Kubuki
氮掺杂碳基质上原子分散的金属在去除难降解有机污染物方面引起了广泛的兴趣。然而，对每个活跃地点的特定结构和这些地点的具体影响的彻底探索仍然是难以捉摸的。本论文采用简单的热解策略，在单原子催化剂(FeNx-C)中构建了一种铁-吡啶N4结构，它对过氧单硫酸盐(PMS)活化有机污染物氧化表现出了良好的催化活性。用X射线吸收光谱和~(57)Fe穆斯堡尔谱验证了FeNx-C催化剂中不同的Fe物种和每个Fe中心的相对含量，它们与前驱体比例和焙烧温度密切相关。高自旋态物种(FeII和FeIII)的相对含量与催化性能呈正相关，决定了FeNx-C/PMS体系中反应物种的生成和电子转移途径。此外，催化性能和理论计算结果表明，高自旋态FeII-N4(S=2)倾向于通过单电子转移过程激活PMS生成硫酸盐和羟基自由基，而FeIII-N4部分(S=5/2)倾向于生成自由能较低的高价铁物种。单原子FeNx-C催化剂由于活性中心的精细可调，在实际废水处理中获得了良好的适用性，同时具有普通水基质的高效阻力。本工作促进了对单原子催化剂中依赖自旋态的过硫酸盐活化的机理的理解，并为基于自旋态描述的优质催化剂的设计提供了指导。
Atomically dispersed metals on nitrogen-doped carbon matrices have attracted extensive interest in the removal of refractory organic pollutants. However, a thorough exploration of the particular structure for each active site and specific effects of these sites still remains elusive. Herein, an Fe-pyridinic N4 structure in a single-atom catalyst (FeNx-C) was constructed using a facile pyrolysis strategy, and it exhibited superior catalytic activity in peroxymonosulfate (PMS) activation toward organic contaminant oxidation. The various Fe species and relative amounts of each Fe site in the FeNx-C catalyst were validated using X-ray absorption spectroscopy and 57Fe Mössbauer spectroscopy, which showed critical dependencies on the precursor ratio and calcination temperature. The positive correlations between relative content of high-spin state species (FeII and FeIII) and catalytic performance were found to determine the reactive species generation and electron transfer pathway in the FeNx-C/PMS system. Moreover, catalytic performance and theoretical calculation results revealed that FeII-N4 in the high-spin state (S = 2) tends to activate PMS to form sulfate and hydroxyl radicals via a one-electron transfer process, while the FeIII-N4 moiety (S = 5/2) is prone to high-valent iron species generation with lower free energy. Benefiting from finely tuned active sites, a single-atom FeNx-C catalyst achieved favorable applicability in actual wastewater treatment with efficient resistance of the common water matrix. The present work advances the mechanistic understanding of spin state-dependent persulfate activation in single-atom catalysts and provides guidance to design a superior catalyst based on spin state descriptions.