Using inorganic silicate precursor/molybdenum peroxo complexes/onium salt interfaces in aqueous acidic media to design mesoporous silica with high molybdenum content and high dispersion

Structure of molybdenum oxide supported on silica SBA-15 studied by Raman, UV–Vis and X-ray absorption spectroscopy

“…The typical shape and band position is also frequently observed at lower densities of 0.1 -0.4 Mo/nm 2 on other silica supports [60,61]. Mo wt% (2.0 Mo/nm 2 ), c) 13.9 Mo wt% (3.2 Mo/nm 2 ) and references Na2MoO4 (e), Na2Mo2O7 (f) and MoO3 (g) in the dehydrated state.…”

“…The typical shape and band position is also frequently observed at lower densities of 0.1 -0.4 Mo/nm 2 on other silica supports [60,61]. In the literature, several interpretations of the observed bands for silica supported molybdenum oxides can be found.…”

Template-free synthesis of molybdenum oxide-based hierarchical microstructures at low temperatures

“…Both of the two liquid samples (Fig. 7a and b) presented the broad absorption bands centered at 230 and 310 nm, which could be attributed to the charge transfer transitions of the characteristic heptacoordination in the peroxomolybdic acid species (from O 2À to Mo(VI), and from O 2 2À to Mo(VI)) [37]. However, a strong absorption at 213 nm could be observed only in the spectrum of the diluted intermediate solution (Fig.…”

“…Compared with this adsorption band, the absorption at 210 and 264 nm could also be observed in the diffuse reflectance spectra of the yellow solid product (Fig. 7c), which are associated with the octahedral and tetrahedral coordination of molybdenum species [37,43]. Based on the similarity of the absorption band at 210 nm, it could be suggested that at the end of the induction period the characteristic structural units in the intermediate solution (octahedral and tetrahedral species) were very similar to those in the solid product obtained subsequently.…”

“…This implied that the ratio of peroxo groups to molybdenum in our samples was 0.25-0.33. In addition, it was speculated that the peroxo groups coordinated with molybdenum according to the previous reports [35][36][37].…”