“…XPS analysis of the surface was carried out by recording the O1s, Zn2p, Zn3p, Zn LMM, Mn2p, Mn3p, and Mn3s XPS regions. Figure 4a shows the two Zn 2+ characteristic peaks corresponding to Zn2p 3/2 and Zn2p 1/2 at binding energies of 1021.24 and 1044.34 eV, respectively, and with a spin-splitting ∆E Zn2p of 23.1 eV, in agreement with the literature [34][35][36]. O1s was deconvoluted in two peaks (Figure 4b), at 529.5 eV, corresponding to the (Zn/Mn)-O metal bond, and at 531.2 eV for OH groups adsorbed on the surface, following the proposal of other authors [26,37,38].…”