Two-Dimensional Iron Tungstate: A Ternary Oxide Layer With Honeycomb Geometry

[Image: see text] The exceptional physical properties of graphene have sparked tremendous interests toward two-dimensional (2D) materials with honeycomb structure. We report here the successful fabrication of 2D iron tungstate (FeWO(x)) layers with honeycomb geometry on a Pt(111) surface, using the solid-state reaction of (WO(3))(3) clusters with a FeO(111) monolayer on Pt(111). The formation process and the atomic structure of two commensurate FeWO(x) phases, with (2 × 2) and (6 × 6) periodicities, have been characterized experimentally by combination of scanning tunneling microscopy (STM), low-energy electron diffraction (LEED), X-ray photoelectron spectroscopy (XPS), and temperature-programmed desorption (TPD) and understood theoretically by density functional theory (DFT) modeling. The thermodynamically most stable (2 × 2) phase has a formal FeWO(3) stoichiometry and corresponds to a buckled Fe(2+)/W(4+) layer arranged in a honeycomb lattice, terminated by oxygen atoms in Fe–W bridging positions. This 2D FeWO(3) layer has a novel structure and stoichiometry and has no analogues to known bulk iron tungstate phases. It is theoretically predicted to exhibit a ferromagnetic electronic ground state with a Curie temperature of 95 K, as opposed to the antiferromagnetic behavior of bulk FeWO(4) materials.