Mechanochemical synthesis of nanocrystalline nickel molybdates

The aim of this study is to establish the possibilities of mechanochemical activation as a successful route for the preparation of NiMoO4 catalysts. A stoichiometric mixture of NiO and MoO3 in a 1:1 molar ratio was subjected to intense mechanical treatment in air using a planetary ball mill for different periods of time. The phase and structural transformations were monitored by X-ray diffraction (XRD) and infrared spectroscopy (IR). The obtained products were analyzed by X-ray photoelectron spectroscopy (XPS). It was found that 5 h milling of the reagents led to complete crystallization to single-phase α-NiMoO4 at room temperature. Mechanochemical activation for 2.5 h resulted in a high-temperature β-NiMoO4 phase under very mild experimental conditions.