Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

O: Oberflächenphysik

O 41: Electronic structure III

O 41.4: Vortrag

Donnerstag, 30. März 2006, 15:45–16:00, WIL B321

Stability of different V2O5 surfaces - theoretical studies — •Malgorzata Witko, Jakub Goclon, and Robert Grybos — Institute of Catalysis and Surface Chemistry, PAS, Cracow, Poland

Vanadia-based catalysts have a well established position both for large-scale applications and as laboratory research material. Experimental studies on vanadia crystallites point out the presence of only (010) surface. On the other hand, a wide spectrum of reactions, which are catalyzed by vanadia-based materials, suggests an important role of other low-index surfaces such as (001) and (100). Therefore, the relative stability of 3 stoichiometric surfaces (010), (100) and (001)V2O5 is studied and compared. Surface energy of low-index terminations is calculated using the periodic DFT approach employing the VASP code. V2O5 has a structure of weakly interacting layers stacked along [010] direction, therefore the (010) surface can be modeled by only one layer, whereas the (001) and (100) surfaces need models containing larger number of layers. It is found that the relative stability of surfaces changes in the following order: (010) > (001) > (100). For all surfaces, ionic positions are optimized. Only for the (001) surface a considerable energetic effect of relaxation is found. Surface free energies obtained from DFT calculations are used to make the Wulff construction for V2O5 crystal.