Electronic structure modulation of covalent organic frameworks by single-atom Fe doping for enhanced oxidation of aqueous contaminants

• Published in: Chemical engineering science 2019-12, Vol.209, p.115211, Article 115211
• Main Authors: Yao, Yunjin, Yin, Hongyu, Gao, Mengxue, Hu, Yi, Hu, Huanhuan, Yu, Maojing, Wang, Shaobin
• Format: Article
• Language: English
• Subjects: Covalent organic framework; Iron; Organic Pollutant; Peroxymonosulfate; Single Atom
• ISSN: 0009-2509; 1873-4405
• DOI: 10.1016/j.ces.2019.115211

[Display omitted] •Single-atom Fe confined into N-doped porous carbon was fabricated.•COF provided active elements and formed well-dispersed and accessible active sites.•Iron doping generated Fe-Nx active sites with electronic structure modulation.•Fe@COF possessed superior activity, benefiting from abundant Fe-Nx active sites.•1O2 and O2∙- were the dominant species in the Fe@COF/PMS system. A strategy for confining single-atom Fe in porous carbon (Fe@COF) from covalent organic framework (COF) was proposed and the Fe@COF catalysts were tested as peroxymonosulfate (PMS) activators for organic pollutants abatement. Iron doping preferentially generated effective single-atom Fe-Nx active sites into the carbon framework with electronic structure modulation, endowing prominent catalytic properties. Both in-situ electron paramagnetic resonance spectrometry and quenching measurements revealed that singlet oxygen (1O2) generated by the Fe@COF/PMS system was primarily responsible for organic degradation rather than sulfate and hydroxyl radicals. The abundant single-atom Fe-Nx active sites with optimized binding energy were found to successfully activate PMS to produce 1O2, while the rich pyrrolic nitrogen may act as the adsorption site of organic molecules, giving rise to remarkable catalytic activity in a broad pH range. The present investigation offers a new strategy to the construction of various COF-immobilized catalysts for an efficient environmental cleanup.