Generating 1O2 and CoIV=O through efficient peroxymonosulfate activation by ZnCo2O4 nanosheets for pollutant control

Heterogeneous advanced oxidation processes (AOPs) based on non-radical reactive species are considered as a powerful technology for wastewater purification due to their long half-lives and high adaptation in a wide pH range. Herein, we fabricate surface Co defect-rich spinel ZnCo2O4 porous nanosheets, which can generate equivalent to Co-IV=O and O-1(2) over a wide pH range of 3.81-10.96 by the formation of amphoteric equivalent to Zn(OH)(2) in peroxymonosulfate (PMS) activation process. Density functional theory (DFT) calculations show Co defect-rich ZnCo2O4 possesses much stronger adsorption ability and more electron transfer to PMS. Moreover, the adsorption mode changes from terminal oxygen Co-O-Co to Co-O, accelerating the polarization of adjacent oxygen, which is beneficial to the generation of equivalent to Co-IV=O and O-1(2). Co defect-rich ZnCo2O4 porous nanosheets exhibit highly active PMS activation activity and stability in p-nitrophenol (PNP) degradation, whose toxicity of degradation intermediates is significant reduction. The Co defect-rich ZnCo2O4 nanosheet catalyst sponge/PMS system achieved stable and efficient removal of PNP with a removal efficiency higher than 93% over 10 h. This work highlights the development of functional catalyst and provides an atomic-level understanding into non-radical PMS activation process in wastewater treatment.