When discussing the XPS spectrum (XPS; X-ray photoelectron spectroscopy), Song and coworkers are telling that "In Fe 2p spectra, the reduction of Fe 3+ to Fe2+ is prominent; this is induced by the increase of C=O and O-C=O bonding" . "Moreover, the atomic contents obtained in the Fe 2p spectra reveal that the pristine iron oxide is composed of α-Fe2O3 [hematite] or γ-Fe2O3.