“…S4a †), the deconvoluted peaks at 641.0, 642.3 and 652.7, and 645.4 and 654.0 eV can be assigned to the Mn 2+ , Mn 3+ and Mn 4+ species, respectively. 38 The existence of tetravalent manganese is due to the fact that a hydroxide anion is a weak field ligand and Mn 3+ ions with a d 4 electronic configuration exist in the high spin state, which are prone to Jahn-Teller distortions and can be oxidized into tetravalent manganese. Additionally, it can be inferred that the manganese ions are mainly in the trivalent form, which should be in the form of MnOOH.…”