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

Abstract

Heterogeneous Fenton-like reactions based on nonradical reactive oxygen species (ROS) are desirable for selective water decontamination, and different pollutants coexisting in real scenarios necessitate a rational combination of multiple ROS for efficient and sustainable decontamination. However, the general one-catalyst-for-one-ROS strategy toward selective ROS generation inevitably renders the combinational process lengthy and cost ineffective. Herein, we developed a new approach to enable the separate but selective generation of two distinct ROS in one catalyst via peroxymonosulfate activation. The unique catalyst is comprised of a graphitic layer bottom-wrapped Fe@Fe₃C encapsulated inside nitrogen-doped carbon nanotubes. The Fe₃C shell facilitates selective formation of surface-bound Fe^IV═O with up to 96.0% selectivity, and the applied electric field could switch ROS generation toward free ¹O₂ with 90.5% selectivity, as enabled by C atoms adjacent to graphite N. One dual-site catalyst enables both high cumulative concentration for Fe^IV═O and ¹O₂ up to 16605 and 7674 μM at 30 min, respectively. Based on such a simple electricity on/off switch mode, a tandem process operated in one unit was proposed to efficiently degrade mixed pollutants of distinct adsorption properties. This study presents a simple but very effective strategy to modulate selective ROS generation that simplifies tandem Fenton-like systems for sustainable water decontamination.