Preparation and coating of molybdenum oxide on alumina submicrospheres by sonochemical method

In this work, we coated molybdenum oxide on submicrospheres of amorphous al umina and crystalline alumina, using a sonochemical method. The sonication products were characterized by transmission electron microscopy, x-ray diff raction, differential scanning calorimetry, thermogravimetric analysis, ult raviolet-visible, Raman, Fourier transform infrared spectroscopy, and surfa ce area (Brunauer-Emmett-Teller) measurements. We found that on crystalline alumina, the blue oxide of molybdenum was formed, while on amorphous alumi na, the presence of an isolated tetrahedrally coordinated Mo oxide species was confirmed. It seems that the amount and types of surface hydroxyl group s on the surface of alumina play: an-important role in both the oxidation o f Mo and the relative content of Mo species in the sonication product, The surface area of the alumina-coated Mo oxide is about 11 times larger than t hat of the bare alumina. An explanation for this change is offered.