Fig. 3: Identification of the primary reactive species.

a Degradation of SMX in the presence of various scavengers in the Co_SA/Zn.O-ZnO/PMS system. b DMPO spin-trapping ESR spectra for DMPO-SO₄^•− in the Co_SA/Zn.O-ZnO/PMS system. c TEMP-based ESR spectra for ¹O₂ in the Co_SA/Zn.O-ZnO/PMS system. d The proportion of active species in the Co_SA/Zn.O-ZnO/PMS system. e LSV curves of ZnO and Co_SA/Zn.O-ZnO electrodes (inset: EIS spectra of ZnO and Co_SA/Zn.O-ZnO). f Cyclic voltammetric curves of ZnO and Co_SA/Zn.O-ZnO electrodes. g Amperometric i-t curve measurements upon the addition of PMS and SMX using ZnO and Co_SA/Zn.O-ZnO as the working electrode. h Open-circuit potential of ZnO and Co_SA/Zn.O-ZnO. i In situ Raman spectra of different reaction systems. j The effect of pre-mixing time on SMX removal in the Co_SA/Zn.O-ZnO/PMS system. The error bars represent the standard deviation of three replicate tests. k Reaction mechanisms in the Co_SA/Zn.O-ZnO/PMS system.