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.