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

Abstract

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. Traditional Fenton and Fenton-like reactions for pollutant removal require a substantial amount of H2O2. In contrast, the heterogeneous metal oxyhalide-based Fenton catalytic approach achieves organic pollutant removal by concentrating and activating them on the catalyst, significantly minimizing H2O2 consumption.