Wu Yijie, Wang Xin, She Tiantian, Li Taozhu, Wang Yunheng, Xu Zhe, Jin Xin, Song Haiou, Yang Shaogui, Li Shiyin, Yan Shicheng, He Huan, Zhang Limin, Zou Zhigang
School of Environment, Jiangsu Engineering Lab of Water and Soil Eco-remediation, Nanjing Normal University, Nanjing, 210023, P. R. China.
School of Mathematics and Physics, North China Electric Power University, Beijing, 102206, P. R. China.
Small. 2024 Jan;20(2):e2306464. doi: 10.1002/smll.202306464. Epub 2023 Sep 1.
Transition metals are excellent active sites to activate peroxymonosulfate (PMS) for water treatment, but the favorable electronic structures governing reaction mechanism still remain elusive. Herein, the authors construct typical d-orbital configurations on iron octahedral (Fe ) and tetrahedral (Fe ) sites in spinel ZnFe O and FeAl O , respectively. ZnFe O (136.58 min F cm ) presented higher specific activity than FeAl O (97.47 min F cm ) for tetracycline removal by PMS activation. Considering orbital features of charge amount, spin state, and orbital arrangement by magnetic spectroscopic analysis, ZnFe O has a larger bond order to decompose PMS. Using this descriptor, high-spin Fe is assumed to activate PMS mainly to produce nonradical reactive oxygen species (ROS) while high-spin Fe prefers to induce radical species. This hypothesis is confirmed by the selective predominant ROS of O on ZnFe O and O on FeAl O via quenching experiments. Electrochemical determinations reveal that Fe has superior capability than Fe for feasible valence transformation of iron cations and fast interfacial electron transfer. DFT calculations further suggest octahedral d-orbital configuration of ZnFe O is beneficial to enhancing Fe-O covalence for electron exchange. This work attempts to understand the d-orbital configuration-dependent PMS activation to design efficient catalysts.
过渡金属是用于水处理中活化过一硫酸盐（PMS）的优异活性位点，但控制反应机理的有利电子结构仍不清楚。在此，作者分别在尖晶石ZnFe₂O₄和FeAl₂O₄的铁八面体（Fe³⁺）和四面体（Fe²⁺）位点上构建了典型的d轨道构型。通过PMS活化去除四环素时，ZnFe₂O₄（136.58 min⁻¹ F⁻¹ cm²）比FeAl₂O₄（97.47 min⁻¹ F⁻¹ cm²）表现出更高的比活性。通过磁光谱分析考虑电荷量、自旋态和轨道排列的轨道特征，ZnFe₂O₄具有更大的键级以分解PMS。使用该描述符，假设高自旋Fe³⁺主要活化PMS以产生非自由基活性氧（ROS），而高自旋Fe²⁺更倾向于诱导自由基物种。通过猝灭实验在ZnFe₂O₄上选择性地以¹O₂为主导的ROS和在FeAl₂O₄上以³O₂为主导的ROS证实了这一假设。电化学测定表明，Fe³⁺在铁阳离子的可行价态转变和快速界面电子转移方面比Fe²⁺具有更优异的能力。DFT计算进一步表明，ZnFe₂O₄的八面体d轨道构型有利于增强Fe-O共价性以进行电子交换。这项工作试图理解依赖于d轨道构型的PMS活化以设计高效催化剂。
