SURFACE AND INTERFACE STUDY OF MOLYBDENUM EVAPORATED ON NIO(100) SURFACES

A great many characterizations have been carried out on NiMo catalysts by means of various techniques. However, little is known about their real surface structure. Molybdenum deposition was performed under uhv on cleaved NiO(100) surfaces. The growth mode was determined by Auger electron spectroscopy, reflection high energy electron diffraction and secondary ion mass spectrometry. The overgrowth of a poorly crystallized MoO2 film is evidenced for deposition at room temperature. Upon thermal treatments the nucleation and growth of nickel islands occur within an amorphous MoOx layer with x > 2. Despite the relative simplicity of this non-supported catalyst, one can consider that the superficial phases obtained in this study may be found at the surface of real NiMo catalysts. © 1990.