Organic assisted hydrothermal route to MoO2/HDA composite microspheres and their characterization

Synthesis of molybdenum oxide/hexadecylamine (MoO2/HDA) microspheres in aqueous solution has been investigated systematically by varying the concentration of the precursor, surfactant and reducing agent, as well as the reaction temperature and duration. To understand this, the nature of the solid has been probed by PXRD, FTIR, UV-visible and SEM equipped with an EDS. The PXRD patterns of as-prepared products reveal that MoO2 microspheres are of monoclinic structure. The bands at 985 and 952 cm-1 reflect the ν(Mo-O) stretch vibration of terminal -MoVI=Ot and -MoIV=Ot groups. UV-vis spectrum of calcined sample exhibits maximum absorption at 358 nm. SEM images reveal that the average diameters of the MoO2 microspheres are in the range 1-3 μm. The reduction of the precursor yields a metastable poorly crystalline oxide of lower valence molybdenum, which is crystallized to α-MoO3 on calcination to 400 deg. C