The chemical and electronic properties of oxygen-modified C/Mo(110): a model system for molybdenum oxycarbides

• Published in: Journal of catalysis 2005, Vol.229 (1), p.30-44
• Main Authors: Hwu, Henry H., Zellner, Michael B., Chen, Jingguang G.
• Format: Article
• Language: English
• Subjects: C/Mo; Carbides; Catalysis; Chemistry; DFT; Exact sciences and technology; General and physical chemistry; NEXAFS; O/C/Mo; Oxycarbides; SXPS; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
• ISSN: 0021-9517; 1090-2694
• DOI: 10.1016/j.jcat.2004.09.014

We have utilized oxygen-modified C/Mo(110) surfaces as model systems to determine the modification effect of oxygen in “oxycarbides.” Using cyclohexene, ethylene, and methanol as probe molecules, we observed that the reactivity of the O/C/Mo(110) surfaces depended strongly on the temperature at which oxygen was introduced onto the C/Mo(110) surface. The reaction pathways were determined using both temperature-programmed desorption (TPD) and high-resolution electron energy loss spectroscopy (HREELS). For example, the O/C/Mo(110) surface obtained by exposing the carbide surface to oxygen at 600 K became chemically inert toward all three molecules. On the other hand, the 900 K O/C/Mo(110) surface was active toward all three molecules, and for the most part retained the Pt-like reaction pathways observed on unmodified C/Mo(110). Furthermore, we have also compared the electronic properties of the O/C/Mo(110) surfaces using two synchrotron spectroscopies, soft X-ray photoelectron spectroscopy (SXPS) and near-edge X-ray absorption fine structure (NEXAFS); the results revealed similar electronic properties between the 900 K O/C/Mo(110) and unmodified C/Mo(110) surfaces.