Boosting PMS Activation Efficiency through Constructed Built-In Electric Field in ZnO/CuO Heterojunctions for Effective Sulfamethoxazole Degradation

Traditional PMS activation catalysts struggle with low charge-separation efficiency and an excessive reliance on single-radical pathways. In this study, a ZnO/CuO heterojunction catalyst prepared by hydrothermal synthesis was used to degrade sulfamethoxazole (SMX) through PMS activation. By applying the catalyst, the SMX degradation rate of 99.64% was achieved within 30 min. Radical-quenching experiments revealed that SO₄^•- (36.7%) and ¹O₂ (33.4%) were the main reactive species, highlighting the significance of the nonradical pathway. Meanwhile, ^•O₂^- and ^•OH respectively account for 15% and 14.9% of the total reactive species and also make a significant contribution to SMX degradation. The ZnO/CuO-3 Schottky interface's built-in electric field was found to enhance charge separation and transfer significantly. After five cycles, the catalyst retained a degradation efficiency above 99%, demonstrating excellent reusability. In this study, the nonradical reaction proportion during PMS activation was increased by modifying the heterojunction's electronic structure, offering a new strategy for designing stable as well as pH-sensitive, antibiotic-degradation catalysts.