Electronic properties, structure and adsorption at vanadium oxide: densityfunctional theory studies

The local electronic structure at the V2O5(010) surface is studied by ab in itio density functional theory (DFT) methods where embedded clusters as lar ge as V20O62H24, representing one or two physical layers of the substrate, are used as models. Results of local binding, charging, and densities of st ates help to characterize the detailed electronic structure of the surface. In addition, electronic and geometric details of surface oxygen vacancies are studied by V2O5(010) surface cluster calculations where oxygen atoms ar e removed from specific surface sites. A comparison of the data, concerning vacancy energies, charging, and geometric relaxation, shows pronounced var iations between different oxygen sites, which gives further insight into po ssible mechanisms of surface relaxation and reconstruction. Further, cluste r calculations of hydrogen adsorption at structurally different surface oxy gen sites (leading to surface OH and H2O) are performed. A comparison of bo nd strengths of surface OH and H2O with that of surface oxygen gives valuab le information as to which oxygen sites are involved in specific adsorption , desorption, and reaction steps.