We have investigated the molecular and dissociative adsorption of a water molecule on the V 2 O 5 (010) surface by means of periodic boundary models and density functional approach. It has been observed that molecular adsorption of water on the V 2 O 5 (010) surface occurs favorably, whereas the dissociation hardly occurs on the stoichiometric surface due to the significant Coulombic repulsion of the lattice oxygens around the exposed vanadium center to the approaching oxygen of the hydroxyl species. For molecular adsorption at the surface oxygen sites, it has been confirmed that hydrogen bonding plays a crucial role, and the adsorption abilities of the surface oxygens correlate with the electron-donating ability from the surface oxygen sites to the water molecules, and with the ratio of the accumulated charge on the adsorption site and the adsorbed water species. As for molecularly adsorbed water species at the exposed vanadium site, the coordination interaction and hydrogen bonding are the important contributions. For both the molecular and dissociative adsorption, it has been elucidated that the vanadyl oxygen plays the most important role among the three surface oxygens and acts as the most favorable adsorption site.

The application of strain to yttria-stabilized zirconia (YSZ), which can be realized by sandwiching a thin YSZ film epitaxially between layers of a material with larger lattice constants, is proposed as a means to enhance oxygen ion mobility. The possible mechanism of such an enhancement was investigated by molecular dynamics using a CeO2–YSZ superlattice. The calculated diffusion coefficient of oxygen ions in the superlattice is some 1.7 times higher than in YSZ alone due to a decreased activation barrier from the strain of the YSZ structure.

The present paper deals with the periodic first-principles density functional (DFT) calculations on hydrogen adsorption on the V2O5(010) surface. The calculated results reveal that the vanadyl oxygen is the most active site for hydrogen adsorption among the three kinds of structurally different lattice oxygens in terms of their coordination with vanadiums. Our calculated harmonic vibrational frequencies of the three types of OH species are found to correlate with their corresponding bond strengths and support their respective reactivity. It is confirmed that the lattice relaxation contributes to the reactivity of the oxygens significantly in all cases while the local environment of adsorption site affects both the geometry and reactivity of the adsorption system only in the case of tricoordinated oxygen. Hydrogen adsorption at these oxygens reduces the surface in different ways. Comparison of the desorption ability of the OH species from the surface shows that removal of the O1H species, formed by H adsorption at vanadyl oxygen, is energetically preferable. The present work demonstrates that the periodic approach gets rid of the artifacts of the cluster method, and thus, first-principles DFT methodology demonstrates its reliability to investigate geometric, electronic, and catalytic properties of transition metal oxide catalysts.

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The coordination structures of Cu ionic species in ZSM-5 zeolite were investigated by molecular dynamics (MD) simulations and molecular orbital (MO) calculations. Al sites were first sought so as to reproduce the square-planar coordination of Cu(II), which is well characterized by the ESR spectra. When two Al's occupy T8 sites in the six-membered ring, the calculated coordination of Cu(II) agreed well with the experimental data. For this Al siting, Cu(II)−O−Cu(II) and two Cu(I)'s were respectively simulated, and the coordination of the former species was found to be consistent with the EXAFS results. Furthermore, from the MO calculation Cu−O−Cu was anticipated to be very reactive and thus might be the active site. The function of zeolite would therefore be the stabilization of this species. On the other hand, Cu dimer was found unstable, and the reaction mechanism based on it was supposed unlikely.