Figure 6 . (a)Mn 3s and (b) O1s XPS spectra of MnOx catalysts (MnO2-H-200, MnO2, Mn2O3 and Mn3O4)
Table 1. XPS results of MnOx catalysts (MnO2-H-200, MnO2, Mn2O3 and Mn3O4)