title: Metal tungstates at the ultimate two-dimensional limit: fabrication of a CuWO₄ nanophase.
abstract: Metal tungstates (with general formula MWO4) are functional materials with a high potential for a diverse set of applications ranging from low-dimensional magnetism to chemical sensing and photoelectrocatalytic water oxidation. For high level applications, nanoscale control of film growth is necessary, as well as a deeper understanding and characterization of materials properties at reduced dimensionality. We succeeded in fabricating and characterizing a two-dimensional (2-D) copper tungstate (CuWO4). For the first time, the atomic structure of an ultrathin ternary oxide is fully unveiled. It corresponds to a CuWO4 monolayer arranged in three sublayers with stacking O-W-O/Cu from the interface. The resulting bidimensional structure forms a robust framework with localized regions of anisotropic flexibility. Electronically it displays a reduced band gap and increased density of states close to the Fermi level with respect to the bulk compound. These unique features open a way for new applications in the field of photo- and electrocatalysis, while the proposed synthesis method represents a radically new and general approach toward the fabrication of 2-D ternary oxides.
authors.affiliation: Surface and Interface Physics, Institute of Physics, Karl-Franzens University A-8010 Graz, Austria.
authors.forename: Martin
authors.initials: M
authors.lastname: Denk
authors.forename: David
authors.initials: D
authors.lastname: Kuhness
authors.forename: Margareta
authors.initials: M
authors.lastname: Wagner
authors.forename: Svetlozar
authors.initials: S
authors.lastname: Surnev
authors.forename: Fabio R
authors.initials: FR
authors.lastname: Negreiros
authors.forename: Luca
authors.initials: L
authors.lastname: Sementa
authors.forename: Giovanni
authors.initials: G
authors.lastname: Barcaro
authors.forename: Ivana
authors.initials: I
authors.lastname: Vobornik
authors.forename: Alessandro
authors.initials: A
authors.lastname: Fortunelli
authors.forename: Falko P
authors.initials: FP
authors.lastname: Netzer