Structure and Oxidizing Power of Single Layer α-V2O5
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Vanadium pentoxide is a layered compound in which V2O5 monolayers are held together by van der Waals forces. It is therefore possible, in principle, to exfoliate the material and form two-dimensional monolayers. Density functional theory is used to calculate the structure and the energy of vacancy formation for hypothetical, two-dimensional V2O5 systems and compare them to the same properties of V2O5 slabs. We study a two-dimensional sheet (infinite in two directions) and two ribbons (infinite in one direction) whose edges are perpendicular to the  or  directions. These edges undergo a substantial reconstruction. When an oxygen vacancy is formed, the formal charge of two vanadium atoms is reduced from 5+ to 4+. The energy of oxygen vacancy formation is higher for the two-dimensional structures than for the corresponding slabs (i.e. it is more difficult to remove oxygen from the edge of a ribbon perpendicular to  than from the (001) surface of a slab). Therefore, the two-dimensional structures are less aggressive oxidants than vanadium pentoxide powders.
KeywordsVanadia Two-dimensional oxide Edge structure Oxygen vacancy formation DFT + U
Financial support was provided by the Department of Energy, Office of Science, Office of Basic Energy Sciences DE-FG03-89ER14048 and the Air Force Office of Scientific Research FA9550-12-1-0147. We acknowledge support from the Center for Scientific Computing at the California NanoSystems Institute and the UCSB Materials Research Laboratory (an NSF MRSEC, DMR-1121053) funded in part by NSF CNS-0960316 and Hewlett-Packard. Use of the Center for Nanoscale Materials was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract DE-AC02-06CH11357.
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