Interface coupling induced built-in electric field to regulate the peroxymonosulfate activation over Co3O4/NiO composite for realizing effective degradation of organic contaminants

Heterogeneous persulfate-based advanced oxidation processes (PS-AOPs) have been regarded as one of the most promising methods in the treatment of wastewater containing antibiotic. Herein, the Co 3 O 4 /NiO composite with built-in electric field is prepared. The existence of built-in electric field can reduce the interface resistance and accelerate the charge transfer, promoting the electron transfer between the Co 3 O 4 /NiO composite and peroxymonosulfate (PMS). Meanwhile, built-in electric field can induce the formation of electron-deficient and electron-rich active areas. With built-in electric field intervention, the activation pathway of PMS over Co 3 O 4 component with electron-deficient area of Co 3 O 4 /NiO is transformed from radical to 1 O 2 , while electron-rich area makes NiO component that has no ability can activate PMS producing SO 4 •− and OH • . As a result, the Co 3 O 4 /NiO composite can effectively activate PMS to realize the rapid degradation of tetracycline. More significantly, a micro reactor equipping with Co 3 O 4 /NiO composite not only displays high removal efficiency of total organic carbon (TOC), but also improves the biodegradability of wastewater containing antibiotic. In short, current work not only clarifies the role of built-in electric field in PMS activation, but also shares some valuable insights into the application of PS-AOPs in practical engineering.