Metal Tungstates at the Ultimate Two-Dimensional Limit: Fabrication of a CuWO4 Nanophase

• Published in: ACS nano Vol. 8; no. 4; pp. 3947 - 3954
• Main Authors: Denk, Martin, Kuhness, David, Wagner, Margareta, Surnev, Svetlozar, Negreiros, Fabio R, Sementa, Luca, Barcaro, Giovanni, Vobornik, Ivana, Fortunelli, Alessandro, Netzer, Falko P
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 22.04.2014
• Subjects: two-dimensional oxide material; Cu tungstate; photoelectron spectroscopy; phonon spectra; density functional theory; ternary oxide; tungsten oxide clusters; scanning tunneling microscopy
• ISSN: 1936-0851; 1936-086X
• DOI: 10.1021/nn500867y

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.