Hidden Complexity in the Chemistry of Ammonolysis-Derived "gamma-Mo2N": An Overlooked Oxynitride Hydride

Published

September 14, 2021

Author(s)

Rick L. Paul, Shobhit A. Pandey, Chi Zhang, Daniah H. Ibrahim, Elise A. Goldfine, Jill K. Wenderott, Roberto dos Reis, Ionnis Spanopoulos, Mercouri Kanatzidis, Michael J. Bedzyk, Vinayak P. Dravid, Gabriela B. Gonzalez, Sossina M. Haile

Abstract

Molybdenum nitrides have been employed in a variety of catalysis and electronic applications. For use in catalysis, the cubic  phase with nominal stoichiometry Mo2N and space group Fm3 ̅m is typically prepared by high temperature reaction of MoO3 with NH3. The literature presents conflicting reports of the possible presence of residual oxygen from typical ammonolysis reactions and how such species may influence the crystal structure and morphology. With the aim of resolving these open questions, a comprehensive study of the chemistry, crystal structure and electronic structure of molybdenum nitride materials prepared by ammonolysis has been undertaken here, with particular focus on the role of reaction temperature. Ammonolysis of MoO3 was carried out at 700 °C and at 800 °C, and yielded single-phase cubic products. Using electron energy loss spectroscopy (EELS), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), prompt-gamma neutron activation analysis (PGAA), and combustion analysis, significant concentrations of oxygen and hydrogen were found in both materials. The stoichiometries deduced from these comprehensive studies are Mo0.65(O0.38,N0.62)H0.57 and Mo0.78(O0.35,N0.65)H0.30, for respective synthesis temperatures of 700 and 800 .

Citation

Chemistry of Materials

Volume

33

Issue

17

Pub Type

Journals

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DOI Link

Keywords

molybdenum nitride, materials analysis, prompt gamma-ray activation analysis, TGA, XPS, EELS

Citation

Paul, R. , Pandey, S. , Zhang, C. , Ibrahim, D. , Goldfine, E. , Wenderott, J. , dos Reis, R. , Spanopoulos, I. , Kanatzidis, M. , Bedzyk, M. , Dravid, V. , Gonzalez, G. and Haile, S. (2021), Hidden Complexity in the Chemistry of Ammonolysis-Derived "gamma-Mo2N": An Overlooked Oxynitride Hydride, Chemistry of Materials, [online], https://doi.org/10.1021/acs.chemmater.1c00617 (Accessed January 2, 2025)