Adsorption of molecular and atomic hydrogen on vacuum-cleaved V2O5(0 0 1)

The (0 0 1) surface of a vacuum-cleaved V2O5 single crystal has been studied using high-resolution electron energy loss spectroscopy (HREELS), UV-photoelectron spectroscopy angular resolved photoemission spectra (ARUPS) and X-ray photoelectron spectroscopy (XPS). Special emphasis was put onto the interaction with molecular and atomic hydrogen and the existence of hydroxyl groups on the surface. Dosage of atomic hydrogen induces reduction of the V2O5(0 0 1) surface as is obvious from the evolution of intensity near to the Fermi edge in the photoelectron spectra. Even after strong reduction no indications of OH groups could be observed in the spectra. Detailed inspection of the ARUPS and HREELS data and comparison with theory leads to the conclusion that the hydrogen induced defects on the surface are most likely missing bridging oxygen atoms whereas the terminal oxygen atoms of the vanadyl groups appear to be stable with respect to removal by atomic hydrogen.