A comparative XPS and UPS study of VO _x layers on mineral TiO₂ (001)-anatase supports

Abstract

Four vanadium oxide layers on mineral TiO 2 (001)-anatase supports with different thickness (3-33Å) were prepared with reactive d.c. magnetron sputtering and were extensively studied with photoelectron spectroscopy. Al Ka radiation and 150 eV synchrotron radiation were used as excitation sources. The evolution of the 2p, 3s and 3p core level line shapes of V and Ti as a function of the vanadium oxide thickness was studied, as well as the O1s and O2s core lines and the valence band. All the V2p spectra of the deposited vanadium oxide layers consist of at least 60% V 5+ , the rest being V 4+ . The V3p region is complicated by multiplet splitting, which prevents the determination of the vanadium oxidation state. The V3p multiplet splitting is different for the two excitation energies. No reduction of the titania support surface due to the vanadium oxide deposition was observed.

Evidences for Different Reaction Sites for Dehydrogenation and Dehydration of Ethanol over Vanadia Supported on Titania

“…The O 1 s binding energy of bulk V 2 O 5 also appears at a very similar position and little shift in O 1 s peak position is observed with increasing vanadia loadings. The shoulder features toward higher binding energies (with distinct peaks at 532 and 533 eV, observed especially at 0.1–0.5 vanadia wt %) are assigned to surface‐bound OH and H 2 O species, respectively, as has been reported on vanadia, TiO 2 , and VO x /TiO 2 . The shoulder feature (labeled as O s , at 528.5 eV) toward lower binding energies of the main O 1 s peak observed especially at 0.3–0.5 V 2 O 5 wt % (indicated by arrows) may be due to surface O atoms bound to reduced Ti sites as has been reported on VO x /TiO 2 as well as on reduced titania, in a form of O 2− …”

“…The main V 2p 3/2 peak at 517 eV is assigned to V 5+ species from the bulk V 2 O 5 phase in V 2 O 5 /TiO 2 . The V 2p 3/2 features at lower binding energies (516–515 eV) at the very low vanadia loadings are due to reduced V species such as V 4+ and V 3+ . The reduced V species can originate from highly dispersed VO x clusters or V species incorporated into the TiO 2 lattice (substituted for Ti 4+ ) …”

The Local and Electronic Structure Study of LuxGd1−xVO4 (0 ≤ x ≤ 1) Solid Solution Nanocrystals

“…The binding energy of O 1 s changed from 529.9 to 530.2 eV, and it first increased and then decreased with the increases in x ( Table S5 ). In addition to the predominant lattice O 1 s peak, a low-intensity component located at 1.5 eV higher (inset of Figure 8 a) could be attributed to the surface-adsorbed hydroxyl groups [ 38 , 39 , 40 ]. The binding energy of V 2 p 3/2 changed from 517.1 to 517.4 eV, similar to the change in the lattice O 1 s ( Figure 8 b and Table S5 ).…”

Photo-enhanced thermal catalytic CO2 methanation activity and stability over oxygen-deficient Ru/TiO2 with exposed TiO2 {001} facets: Adjusting photogenerated electron behaviors by metal-support interactions

“…In addition, the three C 1s peaks at 284.00, 284.80, and 286.10 eV in Fig. 4 are assigned to the hydrocarbon (C-H), graphitic carbon (C sp 2 ), and carbon dioxygen (C-O(O)), respectively [53]. Both 0RT-H and 3RT-H show a higher C-H peak (approximately 284.00 eV) after CO2 methanation (Figs.…”