Polymer-Assisted Growth of Molybdenum Oxide Whiskers via a Sonochemical Process
Whiskers of molybdenum oxides with high aspect ratios were synthesized from peroxomolybdate precursor solutions in the presence of small amounts of poly(ethylene glycol) (PEG) via a sonochemical process at temperatures of 25--70 {sup o}C. Irradiation with ultrasound reduces the time needed for the growth of micrometer-sized whiskers from weeks to a few hours. The simplicity of the sonochemical approach also compares favorably to a hydrothermal/solvothermal process. The morphology, crystal structure, and other characteristics of the whiskers were characterized by scanning electron microscopy, transmission electron microscopy, selective area electron diffraction, energy-dispersive X-ray spectroscopy, wide-angle X-ray diffraction, Raman spectroscopy, thermogravimetric analysis, differential scanning calorimetry, and the Brunauer-Emmett-Teller method. The surface area of the calcified molybdenum oxide whiskers (55.4 m{sup 2}/g) was found to be much higher than those of molybdenum oxide nanofibers (35 m{sup 2}/g){sup 5} or nanorods (13.4 m{sup 2}/g).{sup 6} The growth rate of various crystal faces could be postulated to be controlled by the binding of peroxomolybdate ions to pseudo-crown ether cavities formed by PEG. The reduction of molybdenum oxide to produce mixed-valent oxides and their growth could also be controlled by the reducing ability of PEG. The aspect ratio of the molybdenum oxide whiskers increased with decreasing concentration in the initial peroxomolybdate precursor solution. Whether the precursor solution species was H{sub 2}Mo{sub 2}O{sub 3}(O2){sub 4}(H{sub 2}O){sub 2}, H{sub 2}MoO{sub 2}(O{sub 2}){sub 2}, or MoO{sub 2}(OH)(OOH), the peroxide group in all the species disproportionates to give the final product MoO3 by a catalytic process. On the basis of experimental evidence of the dual role of glycols, a mechanism for the growth of the molybdenum oxide whiskers is proposed.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source
- Sponsoring Organization:
- Doe - Office Of Science
- DOE Contract Number:
- DE-AC02-98CH10886
- OSTI ID:
- 929813
- Report Number(s):
- BNL-80368-2008-JA; TRN: US200822%%1027
- Journal Information:
- Journal of Physical Chemistry B, Vol. 110
- Country of Publication:
- United States
- Language:
- English
Similar Records
Facile sonochemical synthesis of Ag modified Bi{sub 4}Ti{sub 3}O{sub 12} nanoparticles with enhanced photocatalytic activity under visible light
CoTiO{sub 3} via cobalt oxalate-TiO{sub 2} precursor. Synthesis and characterization
Related Subjects
ASPECT RATIO
CRYSTAL STRUCTURE
ELECTRON DIFFRACTION
GROWTH
MOLYBDENUM OXIDES
OXIDES
PRECURSOR
RAMAN SPECTROSCOPY
SCANNING ELECTRON MICROSCOPY
SURFACE AREA
THERMAL GRAVIMETRIC ANALYSIS
TRANSMISSION ELECTRON MICROSCOPY
WHISKERS
X-RAY DIFFRACTION
X-RAY SPECTROSCOPY
national synchrotron light source