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

The local electronic structure at the V2O5(010) surface is studied by ab initio density functional theory (DFT) methods where embedded clusters as large as V20O62H24, representing one or two physical layers of the substrate, are used as models. Results of local binding, charging, and densities of states 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 are removed from specific surface sites. A comparison of the data, concerning vacancy energies, charging, and geometric relaxation, shows pronounced variations between different oxygen sites, which gives further insight into possible mechanisms of surface relaxation and reconstruction. Further, cluster calculations of hydrogen adsorption at structurally different surface oxygen sites (leading to surface OH and H2O) are performed. A comparison of bond strengths of surface OH and H2O with that of surface oxygen gives valuable information as to which oxygen sites are involved in specific adsorption, desorption, and reaction steps.