Activation of peroxydisulfate by defect-rich CuO nanoparticles supported on layered MgO for organic pollutants degradation: an electron transfer mechanism

Heterogeneous activation of peroxydisulfate (PDS) by transition metal oxides offers a promising strategy for organic pollutants removal but suffers from low electron transfer efficiency. Herein, layered MgO supported CuO nanoparticles was prepared by thermal conversion of metal-phenolic networks of Cu²⁺/Mg²⁺ and tannic acid. CuO nanoparticles (∼2 nm) were spatial monodispersed on layered MgO, inducing the formation of electron deficient Cu³⁺ and surface oxygen vacancies and thus facilitated adsorption and activation of PDS. The electron-rich CuO/MgO hybrid catalysts manifested good catalytic performance of PDS activation for organic pollutants removal. At 0.18 g/L of CuO/MgO hybrid catalyst and 0.2 mM of PDS, complete removal of bisphenol A (BPA) was achieved with a high kinetic constant (0.1 min⁻¹, 50 min). Quenching experiments, electron paramagnetic resonance tests, PDS decomposition behaviors, electrochemical analysis and in situ ATR-FTIR and Raman spectroscopy revealed a nonradical pathway of electron transfer for PDS activation. The CuO/MgO hybrid catalysts exhibited wide working pH range from 3 to 11, selective oxidation capability, good resistance to halide ion and high utilization efficiency of PDS, and thus would be a promising candidate for wastewater remediation.