| Full text | |
| Author(s): |
Souza, Eduardo Caetano C.
Total Authors: 1
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| Document type: | Journal article |
| Source: | Journal of Physical Chemistry C; v. 123, n. 40, p. 24426-24435, OCT 10 2019. |
| Web of Science Citations: | 0 |
| Abstract | |
Solid acid-based photocatalysts have been widely pursued to apply in different chemical conversions, as in Fischer-Tropsch synthesis and in the oxidation of alcohols and hydrocarbons. In the present work, layered niobates of composition HxM4-xNb6O17 (M = K, Rb, Cs) and HNb3O8 were synthesized by the sol gel method followed by proton exchange reaction. Local structure modifications due to proton incorporation were evaluated by X-ray powder diffraction and Raman spectroscopy. The Raman spectra point to a decrease in the symmetry of NbO6 groups with vibrational frequencies assigned to variations of Nb-O bond order. Thermally stable acid sites may reach an optimum temperature of 250 degrees C as dehydroxilation begins until total deprotonation at 570 degrees C. Impedance spectroscopy was performed to study the chemical properties of NbO-H bonds by evaluating the proton mobility under dry air and water vapor-saturated atmospheres. The impedance data show that hydrated protons are primarily bonded to the terminal oxygen of NbO6 octahedra as the electrons of hydronium H3O+ ions remain localized. The results suggest that layered HxK4-xNb6O17 hexaniobate merits further investigation as inexpensive and strong solid acid host for the photochemical conversion of gaseous reactants into renewable products at intermediate temperatures. (AU) | |
| FAPESP's process: | 12/15785-0 - Development and Characterization of New Conductor Materials based on Layered Niobates |
| Grantee: | Eduardo Caetano Camilo de Souza |
| Support Opportunities: | Scholarships in Brazil - Post-Doctoral |