Tranca, Diana C.Diana C.TrancaWojtaszek-Gurdak, AnnaAnnaWojtaszek-GurdakZiolek, MariaMariaZiolekTielens, FrederikFrederikTielens2021-05-172021-05-172015-07-30Physical Chemistry Chemical Physics 17 (34): 22402-22411 (2015-07-30)http://hdl.handle.net/11420/9540The geometry, energetic, and spectroscopic properties of molecular structures of silica-supported niobium oxide catalysts are studied using periodic density functional calculations (DFT) and compared with experimental data. The calculations are done for Nb oxide species inserted or grafted in/on an amorphous hydroxylated silica surface. Different positions of the Nb atom/atoms in the silica structure have been investigated. By means of DFT calculations the geometry and the degree of hydration of Nb oxide species with oxidation state +5 have been studied. The local Nb geometry depends on different parameters such as the number of Nb-O-Si groups vs. Nb-O-H groups, the formation of H bonds and the distance between Nb atoms. The interaction between the oxide and silanol groups occurs by formation of Si-O-Nb bonds with chemically and thermally stable Bronsted and Lewis acid sites. UV-Vis, reflection absorption infrared vibrational spectra (RAIRS) as well as various thermodynamic properties have also been investigated in order to get a better insight into the system studied and to provide support to possible experimental studies.en1463-90842015342240222411RSC Publ.PhysikChemieJournal Article10.1039/c5cp03450gOther