Internal electric field triggered charge redistribution in CuO/Fe₂O₃ composite to regulate the peroxymonosulfate activation for enhancing the degradation of organic pollutants

Herein, we adopt a feasible method to synthesize the CuO/Fe₂O₃ composite with heterostructure. Owing to the significant differences in work functions, an internal electric field is built at the interface of heterojunction after the combination of CuO with Fe₂O₃, which can reduce interface resistance and accelerate charge transfer. Interestingly, under the induction of electrostatic interaction provided by internal electric field, the CuO/Fe₂O₃ composite will form electron-rich and electron-deficient active zones. More importantly, the peroxymonosulfate (PMS) can be oxidized by the CuO with electron-deficient active zone to generate SO₅^•‒, subsequently converting into ¹O₂. Meanwhile, the Fe₂O₃ component with electron-rich active zone can provide electrons for PMS to achieve the heterolysis of Fe-O-O, thereby producing the high-valent metal complex (namely ≡ Fe⁵⁺=O). Consequently, the CuO/Fe₂O₃-2-mediated PMS system with good anti-interference ability displays excellent performance in wastewater treatment. Benefiting from the electrophilic reaction of ¹O₂ and ≡ Fe⁵⁺=O, various typical organic pollutants can be ultimately mineralized into CO₂, H₂O and other nontoxic by-products by the CuO/Fe₂O₃-2-mediated PMS system. In short, current work shares some novel insights into the effect of internal electric field on PMS activation, which can provide valuable references for future research.