Enhanced Fe^IV═O Generation via Peroxymonosulfate Activation by an Edge-Site Engineered Single-Atom Iron Catalyst

Area of Science:

• Environmental Chemistry
• Catalysis
• Materials Science

Background:

• The ferryl-oxo complex (Fe^IV═O) is a potent oxidant for degrading organic contaminants.
• Enhancing Fe^IV═O generation on heterogeneous catalysts is crucial but hindered by poorly understood mechanisms.
• Heterogeneous single-atom catalysts offer potential for controlled oxidation reactions.

Purpose of the Study:

• To investigate the role of edge defects in single-atom iron catalysts (FeNC-edge) for promoting Fe^IV═O generation.
• To evaluate the catalytic activity of FeNC-edge for organic contaminant degradation using peroxymonosulfate (PMS) activation.
• To elucidate the mechanism of enhanced Fe^IV═O formation and its application in a continuous-flow system.

Main Methods:

• Synthesis of single-atom Fe catalysts with introduced edge defects (FeNC-edge).
• Peroxymonosulfate (PMS) activation for organic contaminant degradation.
• Electrochemical analysis, in situ Raman spectroscopy, and probe experiments to confirm Fe^IV═O generation.
• Density functional theory (DFT) calculations to understand the electronic effects of edge sites.
• Immobilization of FeNC-edge on a polymeric membrane for continuous-flow testing.

Main Results:

• FeNC-edge demonstrated unprecedented activity for organic contaminant degradation at low catalyst doses.
• Enhanced Fe^IV═O generation was confirmed on the FeNC-edge surface.
• DFT calculations revealed that edge sites facilitate charge transfer from Fe to PMS by concentrating electron density.
• The immobilized FeNC-edge catalyst operated effectively in a continuous-flow system with efficient recycling and minimal iron leaching.

Conclusions:

• Introducing edge defects onto single-atom Fe catalysts is an effective strategy to promote Fe^IV═O generation.
• FeNC-edge catalysts exhibit high efficiency and stability for environmental remediation.
• The developed continuous-flow system offers a practical approach for treating recalcitrant organic pollutants.