A new approach to the synthesis of molybdenum bimetallic nitrides and oxynitrides

Abstract

A simple processing route to molybdenum bimetallic nitrides and oxynitrides has been developed, based on the use of precursors resulting from freeze-drying of aqueous solutions of the appropriate common metal salts. Thermal decomposition of amorphous freeze-dried powders originates crystalline mixed oxides, which have been carefully characterized. Nitridation of the crystalline intermediate having Ni:Mo=2:3 metal ratio led to single-phased Ni₂Mo₃N. For the V-Mo-O-N system, nitridation of both amorphous and crystalline precursors results in bimetallic oxynitrides. In this way, not only the already known V₂Mo(O_xN_y) catalyst but also a new compound of different metal stoichiometry, V₃Mo₂(O_xN_y), has been prepared. The materials have been characterized by X-ray powder diffraction, elemental analysis, scanning electron microscopy, thermogravimetry under air flow, and temperature programmed oxidation. The existence of a solid solution of stoichiometry V_1–zMo_z(O_xN_y) (0≤z≤1) having rock-salt structure is discussed.

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