From Layered Molybdic Acid to Lower-Dimensional Nanostructures by Intercalation of Amines under Ambient Conditions

Nanostructures of varied dimensionality such as rods, scrolls, and disks of molybdenum oxide have been synthesized in gram quantities under ambient conditions using exfoliation of the layers as a synthetic tool. Intercalation of alkylamines (C_nH_2n+2NH₂, where n = 3, 4, 8, 12, and 16) into yellow molybdic acid (MoO₃·2H₂O) and subsequent treatment with nitric acid resulted in molybdenum oxide nanorods, nanodisks, or oxide−amine composite nanorods. The sizes of the nanoparticles range from a few nanometers to micrometers in length and 10 to 200 nm in diameter. Detailed X-ray, scanning electron microscopy, and transmission electron microscopy analyses reveal an inverse relation between the size of the nanoparticles and the chain length of the guest molecules. Infrared and thermogravimetric studies throw light on the driving force for the amine intercalation and the orientation of the intercalated amine molecules.