Mechanochemically tailoring oxygen vacancies of MnO2 for efficient degradation of tetrabromobisphenol A with peroxymonosulfate

Oxygen vacancy (V O ) engineering can efficiently improve the catalytic activity of metal oxides. This work developed a solvent-free mechanochemical method to tailor V O levels on the surface of commercial MnO 2 under ambient conditions. After a typical ball milling treatment at 350 rpm for 20 min, the obtained V O -rich MnO 2 activated peroxymonosulfate (PMS) to completely degrade tetrabromobisphenol (TBBPA) with a pseudo-first-order rate constant of 0.21 min −1 , being 22 times larger than that for non-milled MnO 2 . 18 O-labeling tests confirmed that singlet oxygen was generated from both PMS and lattice oxygen of MnO 2 as dominant active species for the TBBPA degradation. It was clarified that the catalytic activity of MnO 2 depends on not only V O levels, but also the local environment of V O , i.e., V O -associated cations. The Mn 4+ /Mn 3+ redox couple is more important than Mn 3+ /Mn 2+ , and V O improves the oxygen mobility in/on MnO 2 and Mn 4+ /Mn 3+ redox reactions for the activation of PMS.