Hydrothermal Synthesis Research Papers - Academia.edu (original) (raw)

0-, 1- and 2-dimensional nanocrystals of different vanadium oxides were synthesized using hydrothermal
reaction of commercial bulk monoclinic VO2 and V2O3 precursor, which, depending on reaction conditions,
produced nanoparticles, nanoribbons and nanosheets of different vanadium oxides. Addition of acetone
was used to direct growth and produce two-dimensional nanosheets, whose aspect ratio depends on
acetone-to-precursor concentration, while addition of different alcohols as ligands successfully controlled
the nanoribbon size. Variation of pH also changes the product dimensionality, allowing production of
nanosheets at pH , 3, nanoribbons at 3 , pH , 7 and, through inhibition of reaction, nanoparticles at
high pH. Products of different morphology exhibit systematic increase in unit cell volume with decrease in
thickness of nanocrystals. The reaction occurs with VO2+ ion as the primary reactant, requiring only a
source of VO2+ ions, and not necessarily crystalline VO2(M), allowing use of other precursors, like VOSO4.
Calculations indicate that nanoribbon formation is primarily caused by differences in relative stability of
individual crystal planes of VO2. Addition of different amounts of hydrogen peroxide changes the
oxidation state of vanadium to produce V3O7 and V2O5, without affecting the product morphology, while
use of bulk V2O3 as a precursor leads to the formation of V2O3 nanoribbons, nanoleaves and nanoparticles
with similar mechanisms of size and shape control.