3.6.1. Fe(II) and Fe(III) Identification in PBN@SiO<sup>2</sup>

After peak fitting, the spectrum can be de-convolved into three peaks. Figure 10E shows the XPS peaks centered on binding energies of 721.27 and 708.34 eV for Fe 2p1/2 and Fe 2p3/2, respectively; these features are characteristic of the Fe+2 moiety in Prussian blue. In addition, a spectrum shows a peak at a binding energy of 712.12 eV, which corresponds to Fe+3 species. The position of these peaks is in good agreement with the results in the literature for the characteristic Fe+3 and Fe+2 components of Prussian blue compounds [30].
