Hetero-structured high entropy oxides for efficient organic pollutant degradation via peroxymonosulfate activation

Abstract

Transition metal oxides have attracted widespread attention for their ability to remove organic pollutants from wastewater through peroxymonosulfate (PMS) activation. However, the limited catalytic active sites and low intrinsic catalytic activity hinder its further application. Herein, hetero-structured high entropy oxides (Fe, Co, Ni, Cu)₃O₄/CuO are constructed via an in-situ strategy employing Prussian blue analogs (PBAs) as precursors. The prepared catalyst exhibits outstanding performance and flexible applicability as a PMS catalyst, achieving high degradation rates for various organic pollutants within 5 min, including rhodamine B (94.0 %), methyl orange (90.9 %), malachite green (100.0 %), methyl red (90.3 %), tetracycline (100.0 %) and doxorubicin hydrochloride (100.0 %). The results of active species identification and density functional theory (DFT) calculations revealed that the unique structure of the (Fe, Co, Ni, Cu)₃O₄/CuO optimized the d-band centers of the metallic active sites and the absorption energy of PMS. This accelerates the production of SO₄^•- and •OH, and ¹O₂ in the system, effectively attacking and degrading pollutants. This work provides a low-cost, easy-to-construct, and universal strategy for designing hetero-structured high entropy oxides, which have broad potential for wastewater treatment and other catalytic applications.