Synergistic dual-metal site Ni₆MnO₈ boosting regulated singlet oxygen and electron transfer pathways via persulfate activation for effective bisphenol A degradation

The combined pathways of singlet oxygen (¹O₂) and electron transfer process (ETP) in persulfate-based advanced oxidation processes (PS-AOPs) demonstrated superior performance of pollutant degradation, because ETP can directly capture electrons from pollutants and the ¹O₂ pathway will avoid oligomer formatted via ETP. However, to design spatially active sites for peroxymonosulfate (PMS) activation to generate regulatable/synergistic ETP and ¹O₂ pathways remains a giant challenge. Therefore, we designed Ni₆MnO₈ (NMO-2) materials with spatial dual-metal sites to activate PMS for bisphenol A (BPA) removal via regulatable ETP and ¹O₂ pathways. The NMO-2 exhibited remarkable PMS activation capability, completely degrading 10 mg/L BPA within 2 min at low PMS dosages. Notably, the specific surface area activity of NMO-2 for BPA degradation was 0.4155 L min⁻¹ m⁻², about 16 and 8 times higher than both of pure Mn₃O₄ and NiO, respectively. Furthermore, experimental and theoretical results identified that Ni-O-Ni sites boosted ETP from BPA molecule to PMS and adjacent Ni-O-Mn sites were conducive to generate ¹O₂. Additionally, the NMO-2/PMS system exhibits excellent environmental robustness towards the electron-rich phenolics degradation. Overall, this study proposes an innovative strategy for establishing adjacent centers to modulate PMS activation, thereby paving a robust framework for advanced persulfate-driven environmental remediation systems.