In situ H₂O₂ production from self-sufficient heterogeneous Fenton reaction over Fe⁰/MoS_2-x for potential environmental remediation applications

Fenton reaction technology has worked well in water and wastewater treatment; however it is often limited by such problems as continuous external supply of H₂O₂, slow Fe³⁺/Fe²⁺ cycle rate, high energy requirements, and maintenance of low pH during operation. Herein, a novel self-sufficient heterogeneous Fenton system based on Fe⁰/MoS_2-x was designed, fabricated, and optimized to effectively address these problems. The combined presence of Fe⁰ and sulfur vacancies sites in MoS_2-x played a pivotal role in the generation of H₂O₂via two-step single-electron reduction process without any energy consumption. The existence of dual active sites resulted in a considerable increase in the H₂O₂ yield (up to 0.6 mM/g/h) in a pH-neutral aqueous solution. Furthermore, the Fe³⁺/Fe²⁺ cycle rate was accelerated by Mo⁶⁺/Mo⁴⁺/Mo^δ+ sites. The factors collectively contributed to the impressive performance of the reaction in degrading complex pollutants (e.g., polyethylene, a model plastic matter) under pH-neutral conditions. In addition to its outstanding catalytic performance, Fe⁰/MoS_2-x exhibited superior reusability and stability. Notably, the catalyst reactivity was well sustained in the presence of common competitive factors such as inorganic anions and dissolved organic pollutants, and for other polymer types. This study demonstrates that Fe⁰/MoS_2-x with impressive self-sufficient Fenton reaction capacity has greater potentials for water and wastewater treatment.