High-entropy-modulated localized dipole in a perovskite oxide for selective photo-Fenton-like water decontamination.

Continuous discharge of persistent emerging contaminants has caused various environmental problems. A number of technologies have been developed and applied for treatment, one of which is photo-Fenton-like catalysis due to its high efficiency and mild operational conditions. However, achieving higher contaminant degradation with better selectivity remains challenging. Herein, we develop a high-entropy perovskite (HE-CaZrO3-x) as a photo-Fenton-like catalyst with enhanced localized dipoles for tetracycline decontamination. By disrupting long-range atomic ordering, high-entropy regulation can not only lower the formation energy of oxygen vacancies (OV), but also enhance the metal-oxygen covalency and promote charge redistribution, thereby generating polarized OV-Zr dual reaction sites with pronounced charge asymmetry. This asymmetric structure enables differentiated dual-site adsorption of reactants and shortens interaction distances. Under irradiation, an internal electric field induced by localized dipoles can ensure the efficient separation of photoexcited carriers. These effects enhance the generation of reactive oxygen species and favor a 1O2-dominated nonradical pathway. Accordingly, the HE-CaZrO3-x-based photo-Fenton-like system achieved 96.8% tetracycline removal and 40.8% total organic carbon removal at the end of treatment lasting 18 min, while maintaining high efficiency in the presence of various coexisting ions. More importantly, a supported HE-CaZrO3-x membrane can sustain over 99% tetracycline removal during 3-h continuous flow-through operation with low metal leaching. The study provides a viable route for advancing efficient and selective photo-Fenton-like technologies for water purification.