title: Fabrication of complex model oxide catalysts: Mo oxide supported on Fe3o4(111).
abstract: Industrial catalysts for the oxidation of methanol to formaldehyde consist of iron molybdate [Fe2(MoO4)3]. Using a variety of techniques we have previously shown that the surface of these catalysts is segregated in MoO3, and in order to understand the relationship between surface structure and reactivity for these systems we have begun a surface science study of this system using model, single crystal oxides. Model catalysts of molybdenum oxide nanoparticles and films on an Fe3O4(111) single crystal were fabricated by the hot-filament metal oxide deposition technique (HFMOD), where molybdenum oxides were produced using a molybdenum filament heated in an oxygen atmosphere. Low energy electron diffraction (LEED), X-ray photoelectron spectroscopy (XPS), and scanning tunnelling microscopy (STM) have been used to investigate molybdenum oxide nanoparticles and films deposited on Fe3O4(111). The molybdenum oxide film forms in the highest oxidation state, +6, and is remarkably stable to thermal treatment, remaining on the surface to at least 973 K. However, above approximately 573 K cation mixing begins to occur, forming an iron molybdate structure, but the process is strongly Mo coverage dependent.
authors.affiliation: Wolfson Nanoscience Laboratory, Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Park Place, Cardiff CF10 3AT, UK.
authors.forename: Chanut
authors.initials: C
authors.lastname: Bamroongwongdee
authors.forename: Michael
authors.initials: M
authors.lastname: Bowker
authors.forename: Albert F
authors.initials: AF
authors.lastname: Carley
authors.forename: Philip R
authors.initials: PR
authors.lastname: Davies
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Davies
authors.forename: Dyfan
authors.initials: D
authors.lastname: Edwards