Surface species and the stability of γ-Mo2N

✍ Scribed by Z.B. Wei; Q. Xin; P. Grange; B. Delmon

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 537 KB
• Volume: 101-103
• Category: Article
• ISSN: 0167-2738
• DOI: 10.1016/s0167-2738(97)00182-3

✦ Synopsis

The surface species of passivated and nonpassivated Mo,N and their stability at elevated temperature in various environments have been investigated by thermal programmed desorption with mass spectrometry (TPD-MS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results demonstrate that two types of NHx and H species remain on fresh Mo,N, and a small amount of weakly adsorbed NHx species is present on passivated Mo,N. During heating at 1000°C in He, fresh Mo,N transforms first from y-Mo,N to P-Mo,N and then decomposes to metallic MO. No obvious change of the crystalline phase occurs for passivated Mo,N before its decomposition or reduction. The XRD spectra showed a high stability of the Mo,N bulk structure against sulphidation. XPS data indicated that some changes of the surface composition occurred in sulphided Mo,N. Oxygen incorporated during passivation reacted with sulphur and formed a thin layer molybdenum of sulphide covering the nitride surface.