One Heterogeneous Catalyst Drives Two Selective Fenton-like Reaction Modes for Sustainable Water Decontamination

Area of Science:

• Environmental Chemistry
• Materials Science
• Catalysis

Background:

• Nonradical reactive oxygen species (ROS) are crucial for selective water decontamination.
• Current methods often use a one-catalyst-for-one-ROS approach, leading to inefficient and costly processes for complex pollutant mixtures.
• Developing a single catalyst capable of generating multiple ROS selectively is essential for advanced water treatment.

Purpose of the Study:

• To develop a novel catalytic system for the separate and selective generation of two distinct ROS using a single catalyst.
• To investigate the mechanism of ROS generation and the effect of an electric field on selectivity.
• To demonstrate the efficiency of the dual-ROS generating catalyst in degrading mixed pollutants via a tandem process.

Main Methods:

• Synthesis of a composite catalyst: Fe@Fe3C encapsulated within nitrogen-doped carbon nanotubes with a graphitic layer.
• Activation of peroxymonosulfate to generate ROS.
• Application of an external electric field to modulate ROS selectivity.
• Characterization of ROS generation (FeIV═O and 1O2) and pollutant degradation.

Main Results:

• The Fe3C shell selectively generated surface-bound FeIV═O (96.0% selectivity).
• An applied electric field switched ROS generation to free 1O2 (90.5% selectivity) via C atoms adjacent to graphite N.
• The dual-site catalyst achieved high cumulative concentrations of FeIV═O (16605 μM) and 1O2 (7674 μM) within 30 minutes.
• A tandem process in one unit efficiently degraded mixed pollutants with distinct adsorption properties.

Conclusions:

• A simple strategy was developed to modulate selective ROS generation in a single catalyst.
• The electric field 'on/off' switch mode simplifies tandem Fenton-like systems for sustainable water decontamination.
• This approach offers a cost-effective and efficient solution for treating complex industrial wastewater.