The chemistry at stake is the activation of peroxymonosulfate, or PMS, a persulfate oxidant that has become a mainstay of so-called Fenton-like water treatment. When PMS is activated on a catalytic surface, it generates reactive oxygen species, chiefly sulfate and hydroxyl radicals, capable of shredding persistent organic contaminants such as bisphenol A. But the activation step consumes electrons from the catalytic metal centers. In conventional systems, high-valent or oxidized metal species accumulate on the surface, the electron reservoir drains, and the catalyst gradually loses its punch. Operators must then either replace the catalyst, regenerate it with external reductants, or supply electrical energy to push the spent centers back into their active states, all of which inflate the cost and complexity of treatment.

The Peking University team, led by corresponding author Haodong Ji, attacked this bottleneck at the level of electronic structure. They fabricated catalysts based on iron disulfide, FeS2, doped with a small but decisive quantity of molybdenum, at just 0.39 weight percent. The crucial design choice was to incorporate the molybdenum in its divalent, high-spin state, Mo2+. High-spin configurations place electrons in orbitals singly before pairing them, and in this case the arrangement leaves the element’s active 4d orbitals energetically available for electron exchange. That availability, the researchers found, allows the doped molybdenum to do something remarkable: it spontaneously enriches contaminant molecules at the catalyst surface and pulls electrons out of them, exploiting the fact that many organic pollutants are, from an electrochemical standpoint, electron-rich.

This contaminant-to-catalyst electron transfer is the conceptual centerpiece of the work. As high-spin iron centers donate electrons to activate PMS and generate radicals, they become oxidized and would normally deactivate. The doped Mo2+ acts as a relay, harvesting electrons from the adsorbed pollutants and passing them back to the iron centers, restoring the reactive sites in a self-driven cycle. The authors describe this as a contaminant-to-catalyst electron replenishment pathway, driven primarily by the high-spin molybdenum and synergistically assisted by the lattice sulfur of the FeS2 host. In effect, the pollutant pays for its own destruction: the same molecule that would otherwise foul the catalyst becomes the electron source that keeps the catalyst alive.

The practical consequences are striking. In a continuous-flow reactor, roughly 800 milligrams of the 0.39 weight percent Mo-FeS2 catalyst maintained high activity for over 15 days, treating a total of 216 liters of bisphenol A-containing wastewater. By the team’s assessment, that endurance surpasses most Fenton-like systems reported to date, where catalysts typically fade within hours to a few days under comparable conditions. For a water treatment field where catalyst lifetime directly translates into operating cost, a material that keeps working for weeks without regeneration represents a meaningful step toward practical deployment rather than laboratory demonstration.

Behind the durability lies a subtle interfacial mechanism that the researchers probed with ab initio molecular dynamics simulations. These first-principles simulations, which track atoms and electrons in real time using quantum mechanical forces, revealed that the oxidation at the catalyst-water interface proceeds through proton-coupled electron transfer, a concerted process in which a proton and an electron move together between the contaminant and the surface. This interfacial radical oxidation pathway has a second benefit beyond catalyst restoration: it keeps the destructive radicals close to the surface rather than allowing them to migrate freely into bulk solution. Radicals that wander into the water column are easily quenched by background species such as natural organic matter, chloride, and carbonate, wasting oxidizing power. By confining the reaction to the interface, the proton-coupled mechanism reduces radical migration and channels more of the oxidation capacity into full mineralization of the contaminants, converting them toward harmless end products rather than partially oxidized intermediates.

The team also confronted the scale-up challenge that derails many promising catalysts. They established a scalable synthesis route capable of producing the Mo-FeS2 catalyst at the kilogram scale, an order of magnitude beyond the gram quantities typical of laboratory studies. To translate the powder into a deployable form, they immobilized the catalyst onto sponges, creating robust composite materials that could be handled in real treatment scenarios without the loss of fine particles into treated water. These sponge composites were then tested against a demanding real-world benchmark: the selective elimination of trace emerging contaminants, compounds such as pharmaceuticals and endocrine disruptors that appear at microgram or nanogram concentrations, from four different types of municipal wastewater.

That real-matrix performance matters because actual wastewater is a hostile environment for advanced oxidation. It contains competing scavengers, suspended solids, and a cocktail of dissolved species that can short-circuit radical chemistry. A catalyst that performs brilliantly in ultrapure laboratory water but collapses in a municipal effluent stream offers little value. By demonstrating selective trace-contaminant removal across four distinct municipal wastewater matrices, the study provides evidence that the self-restoring mechanism survives contact with the complexity that defines real treatment plants, though the authors note that further engineering work remains before full-scale implementation.

The broader significance of the work lies in the design principle it establishes. Rather than searching for ever more active catalytic sites, the researchers focused on the sustainability of those sites, asking how a catalyst could restore itself using resources already present in the stream being treated. The answer, a high-spin dopant with accessible d orbitals positioned to shuttle electrons from pollutants to spent iron centers, turns the contaminant load from a liability into an asset. This reframing could guide the development of durable catalysts well beyond the FeS2-PMS system, informing the design of materials for electrocatalysis, photocatalysis, and other redox processes where reactive centers are consumed faster than they are regenerated.

For a world grappling with persistent organic pollutants in water supplies, from bisphenol A to the ever-growing list of emerging contaminants, the economics of treatment often decide which technologies leave the laboratory. A catalyst that extends its own service life by harvesting electrons from the pollutants it destroys, requires no external energy or chemical additives for regeneration, can be manufactured at kilogram scale, and holds up in real municipal wastewater addresses several of those economic barriers at once. The study, published open access in Nature Communications with the DOI 10.1038/s41467-026-78165-w, was supported by the National Natural Science Foundation of China, the Shenzhen Science and Technology Program, and the Innovation Team Project for General Universities in Guangdong Province, and the authors declare no competing interests. If the contaminant-to-catalyst electron replenishment strategy proves generalizable, the self-healing catalyst may become a fixture of next-generation water purification, quietly repairing itself as it cleans.

Subject of Research: Self-restoring Mo-doped FeS2 Fenton-like catalysts for sustained peroxymonosulfate activation and wastewater decontamination

Article Title: Self-restoration of reactive centers via contaminant-to-catalyst electron replenishment for sustained Fenton-like activity

Article References: Li, Y.-H., Chen, A., Hu, X., Liu, M., Xu, N., Borthwick, A. G. L., & Ji, H. (2026). Self-restoration of reactive centers via contaminant-to-catalyst electron replenishment for sustained Fenton-like activity. Nature Communications. https://doi.org/10.1038/s41467-026-78165-w

Image Credits: AI Generated

DOI: 10.1038/s41467-026-78165-w

Keywords: Fenton-like catalysis, peroxymonosulfate activation, water treatment, iron disulfide, molybdenum doping, electron replenishment, bisphenol A, advanced oxidation processes, proton-coupled electron transfer, catalyst self-restoration, emerging contaminants, wastewater purification