Metal oxyhalide-based heterogeneous catalytic water purification with ultralow H₂O₂ consumption

In the quest for advanced water treatment via Fenton and Fenton-like reactions, minimizing the hydrogen peroxide (H₂O₂) usage by improving its activation efficiency is a critical goal. Here we report a metal oxyhalide (MOX)-based Fenton reaction system that differs fundamentally from traditional ones in pollutant removal pathway and mechanism. The MOX/H₂O₂ system enables efficient coupling and polymerization of organic pollutants via mild surface direct oxidation, bypassing the generation of reactive oxygen species. As a result, pollutants are translocated and removed from water with ultralow H₂O₂ consumption, avoiding the formation of toxic by-products. It achieves up to 80% pollutant (50% total organic carbon) removal at a H₂O₂-to-pollutants molar ratio of 2:1, outperforming conventional Fenton systems, which are operated at ratios ranging from 20:1 to 1,000:1. The success of these catalytic systems is attributed to the synergistic actions of O-bridging M and X sites on the catalyst surface, which selectively activate pollutants and H₂O₂, respectively. The catalyst could be extended to low-cost and environmentally benign MOX materials such as BiOI, FeOCl and VOCl, and be adopted to construct a dynamic membrane filtration catalytic system for high-performance and energy-saving abatement of micropollutants in water, providing a promising water purification paradigm.