Presence of surface vanadium peroxo-oxo umbrella structures in supported vanadium oxide catalysts: fact or fiction?

Recent debates over the active site structure of supported vanadia/silica catalysts have suggested the existence of a surface vanadium peroxo-oxo "umbrella" structure. This study definitively demonstrates with Raman and UV-vis spectroscopy that the surface vanadia peroxo-oxo umbrella-like structure is not present for both hydrated and dehydrated supported vanadia catalysts such as supported vanadia on silica. The vanadia peroxo-oxo umbrella structure, however, is present in vanadium haloperoxidase (VHPOs) enzymes and metal-organic compounds designed to mimic VHPOs.