Xilin Yin

Periodic density functional study on V2O5 bulk and (001) surface

Abstract Density functional calculations on periodic models are performed to investigate the structural and electronic properties of both V2O5 bulk and (001) surface. Full geometry optimizations of both V2O5 bulk and (001) surface are presented. For the bulk, the optimized structure is very close to the experimental one, the calculated band gap and binding energy are in very good agreement with experimental values, from population analysis it is observed that vanadyl oxygens are least ionic (O−0.37), doubly coordinated oxygens are ionic (O−0.56), while triply coordinated oxygens become the most ionic (O−0.68). The structural and electronic properties of the surface are very close to those of the bulk. The interlayer interaction is mainly electrostatic and is found to be 4 kcal/mol. Surface acidic and basic properties are described in terms of projected density of states analysis.

Active site and mechanism of the selective catalytic reduction of NO by NH3 over V2O5: A periodic first-principles study

Periodic first-principles density functional (DFT) calculations have been performed to give an understanding of the active site and mechanism for the selective catalytic reduction (SCR) of NO by NH3 over V2O5 in the presence of gaseous oxygen. Two synergetic functional groups, i.e. dual vanadium sites, have been found on the V2O5(010) surface: the hydroxy group (V–OH) containing vanadyl oxygen for the formation of NH4+ species, and the VO group for the activation of the NH4+ formed. The results have revealed that NH3 is adsorbed preferentially on the Bronsted acid, and the NO hardly combines with the surface lattice oxygens to form NO2, but rather gaseous NO interacts with the pre-adsorbed NH4+ species to release N2 and H2O. This study suggests that the catalytic process of the SCR reaction follows an Eley–Rideal type mechanism.

Structure of TiO2 surfaces: a molecular dynamics study

Molecular dynamics was used to investigate surface relaxations of the three titanium dioxide phases (rutile, anatase and brookite). Atoms with small coordination relax much more than bulk like atoms. They undergo vertical as well as lateral relaxations to compensate the missing bonds at the top layer. The driving force which determines the direction of the relaxation seems to be the improvement of local environments of top layer atoms.

Electronic and structural features of Pd3 cluster on MgO(100) surface cluster

Abstract The structural characters and the electronic features of Pd3 cluster on the MgO(100) surface cluster were investigated by performing density functional calculations. The geometric features of the cluster shape of the Pd3 cluster depended on the kinds of neighboring atoms interacting with the Pd atoms. The metal–support interatomic distance was compared with experimental results and the quantitative consistency was found. The dissociation of the Pd3 cluster occurred, indicating the way of the bond breaking of metal cluster.

Molecular dynamics study on the stability of γ-Al2O3 surfaces

Molecular dynamics method was applied to investigate the structure and stability of γ-Al2O3 surface with reference to three plane indices, namely, (100), (110), and (111). Analyses of coordination number shows that surface tetrahedral Als were found to have more mobility than octahedral Als. The largest change of the coordination number was observed in the (111) surface, which matches with the largest relaxation energy. The relaxation energies of (100) and (110) surfaces were found to be almost equal, and the stability of the octahedral Als in these surfaces were compared from the analyses of the coordination numbers.