Precise coordination of high-loading Fe single atoms with sulfur boosts selective generation of nonradicals
Xunheng Jiang, Binghui Zhou, Weijie Yang, Jiayi Chen, Chen Miao, Zhongyuan Guo, Hao Li, Yang Hou, Xinhua Xu, Lizhong Zhu, Daohui Lin, Jiang Xu
Abstract
Nonradicals are effective in selectively degrading electron-rich organic contaminants, which unfortunately suffer from unsatisfactory yield and uncontrollable composition due to the competitive generation of radicals. Herein, we precisely construct a local microenvironment of the carbon nitride–supported high-loading (~9 wt.%) Fe single-atom catalyst (Fe SAC) with sulfur via a facile supermolecular self-assembly strategy. Short-distance S coordination boosts the peroxymonosulfate (PMS) activation and selectively generates high-valent iron–oxo species (Fe IV =O) along with singlet oxygen ( 1 O 2 ), significantly increasing the 1 O 2 yield, PMS utilization, and p -chlorophenol reactivity by 6.0, 3.0, and 8.4 times, respectively. The composition of nonradicals is controllable by simply changing the S content. In contrast, long-distance S coordination generates both radicals and nonradicals, and could not promote reactivity. Experimental and theoretical analyses suggest that the short-distance S upshifts the d -band center of the Fe atom, i.e., being close to the Fermi level, which changes the binding mode between the Fe atom and O site of PMS to selectively generate 1 O 2 and Fe IV =O with a high yield. The short-distance S-coordinated Fe SAC exhibits excellent application potential in various water matrices. These findings can guide the rational design of robust SACs toward a selective and controllable generation of nonradicals with high yield and PMS utilization.