Identification of a new form of monomeric vanadia species in silica gel

A new form of isolated VO43- near mobile Na+ ions in silica gel, but without strong V–O–Si linkages unlike the previously reported isolated monomeric vanadia species, was identified. Our VO43- species have motionally averaged NMR spectra mainly resulting from mobile Na+ ions nearby rather than the dynamics of VO43- species themselves. This VO43- species as well as NaVO3 · 1.89H2O were produced, upon aging, from decavanadate ions in vanadia–silica composite gel with V/(V + Si) = 2.3%. In addition, this work demonstrates the usefulness of the employing multinuclear solid state NMR and XRD techniques together for the characterization of inhomogeneous nano-composite materials.