Vanadium oxide foams: An insight into the structure of the vanadium oxide walls

Vanadium oxide foams have been prepared by mixing V2O 5 with hydrogen peroxide and a solution of 1-hexadecylamine. The resulting yellow foams (YF) have been characterized by different methods including X-ray diffraction, thermal analyses, scanning and transmission electron microscopy, infrared spectroscopy, electron spin resonance, and 51V MAS NMR spectroscopy. The local environment of vanadium probed by 51V MAS NMR consists of tetrahedral and octahedral vanadium sites corresponding to the decavanadate [HxV10O 28](6-x)- and [V4O7] 4-/[V2O7]4- polyanions. This composition is in fair agreement with the reactivity of YF under acidic or basic conditions. Finally, a model for the YF structure based on amine layers intercalated with [HxV10C28](6-x)- and [V4O10]4-/[V2O7] 4- polyanions is proposed. © 2005 American Chemical Society