Interface-engineered Mn3O4-Mn5O8 nanohybrid activated PMS via optimized Mn valence cycling for enhanced tetracycline removal

Antibiotic residues pose a serious threat to aquatic environment, underscoring the urgency of developing efficient and stable advanced oxidation technologies. While the activation process based on peroxymonosulfate (PMS) shows great promise, its efficacy is highly dependent on the performance of the catalyst. In this study, a novel Mn 3 O 4 -Mn 5 O 8 nanohybrid was successfully synthesized and its performance in activating PMS for the degradation of tetracycline (TC) was systematically evaluated. By constructing an electron-rich interface, the nanohybrid achieved optimized manganese valence distribution and efficient cycling, leading to significantly enhanced catalytic activity. In the PMS system, the Mn 3 O 4 -Mn 5 O 8 attained 99.4% TC removal within 30 min, with the reaction rate constant (0.150 min⁻ 1 ) significantly exceeding those of the Mn 3 O 4 (0.052 min⁻ 1 ) and Mn 5 O 8 (0.066 min⁻ 1 ) systems, while the manganese leaching rate (3.65%) was much lower than that of unstable Mn 3 O 4 (8.53%). Mechanistic investigations revealed that the outstanding performance originated from interface-driven manganese valence cycling and electron transfer, which synergistically regulated both radical (O 2 ⁻) and non-radical ( 1 O 2 ) pathways. Furthermore, the catalyst exhibited good anti-interference capability in complex water matrices and cycling stability. This work provided a novel design principle centered on interface engineering and valence state synergy for developing high-performance manganese-based catalysts in PMS-driven water purification.