Synthesis and structural characterization of MoO3 phases obtained from molybdic acid by addition of HNO3 and H2O2

Orthorhombic (alpha) MoO3 and monoclinic (beta) MoO3 were successfully synthesized by cation-exchange of sodium molybdate solution applying three different routes: i) pure precursor molybdic acid solution (H2MoO4), ii) addition of HNO3 to a precursor and iii) addition of 35% H2O2 to a precursor. By route i) pure orthorhombic (alpha) MoO3 Was synthesized. Pure monoclinic (beta) MoO3 Was obtained in the presence of HNO3. A polyphase product containing 72% monoclinic (beta) MoO3 and 28% orthorhombic (alpha) MoO3 was obtained in the presence of 35% H2O2. The products obtained were characterized by XRD, IR and SEM analysis. The morphology of MoO3 strongly depended on the synthesis method applied. Smaller crystals with uniform shape were obtained in the presence of HNO3 and 35% H2O2.