Surface modification of ZrO2 nanopowder with oxovanadium species using slurry deposition and impregnation methods

Structural differences in zirconia-supported vanadia, containing 3 mol% V2O5, obtained by slurry deposition and wet impregnation were elucidated using Raman, EPR and XRD methods, supported by Rietveld refinement. The preparation method strongly determines both the heterogeneity of the surface VOx species and incorporation of the V4+ ions into the zirconia matrix. Slurry deposition favors the formation of isolated or two-dimensional oxovanadium clusters, whereas impregnation leads to agglomerated nanocrystalline V2O5. The stability of surface vanadium was discussed in terms of its reducibility and changes in the temperature of the tetragonal to monoclinic ZrO2 phase transition, induced by surface doping.