Built-In Electric Field Augments Hypersalinity Resistance of Heterostructured Metal Oxides for Efficient Fenton-like Catalysis

Fenton-like oxidation processes for saline wastewater treatment are plagued by high energy/chemical consumption, mainly due to severe interferences by the high-concentration inorganic salt. Such salt inhibition can be partially alleviated by shifting to nonradical catalytic processes, but the surface-accumulated salt ions in heterogeneous catalytic systems still cause electrostatic and steric hindrance to restrict the interfacial reactant transfer. Herein, we fabricated a heterostructured CuO/ZnFe₂O₄ catalyst that provides a built-in electric field (BIEF) to strengthen the reactant-catalyst interaction and weaken the salt interferences. Specifically, the electron-rich CuO component favors electrostatic repelling of chlorine ions (Cl^-), while electron-deficient ZnFe₂O₄ provides a compressed electrical double layer to strengthen peroxydisulfate adsorption and pollutant diffusion. Consequently, CuO/ZnFe₂O₄ exhibited superior hypersalinity resistance in Fenton-like catalysis, maintaining almost unchanged decontamination activity in a 500 mM Cl^- solution. It also demonstrated high stability and robustness for the treatment of real hypersaline industrial wastewater, achieving over 80% tetracycline removal during a 15-h continuous operation in a fixed-bed reactor. Our work presents insights into BIEF-driven salt resistance via heterostructure design and offers low-carbon advanced oxidation technologies for hypersaline wastewater treatment.