Typical Synthesis and Environmental Application of Novel Ti Nanoparticles - Advanced Materials for Agriculture, Food and Environmental Safety - page 436

hv

Reduction

HO NO 2

HO NH 2

+

NaBH 4 +

FNT1 FNT1

NaBH 4

HO NO 2 UV light

HO NH 2

FNT1

Figure 15.12 UV-Vis absorbance changes during the reaction in presence of catalyst and
UV-light, and also color changes of the p-NP solution.

captured, forming Nb 4+ . Hence, this Nb 4+ is faster at reducing p-nitrophenol
to 4-AmP. However, in the nanoparticle phase, the surface-to-volume ratio
increases drastically and the surface atoms include an increasing fraction
of the total particulate volume having high defect structures. h us they are
expected to show drastically improved catalytic properties. However, the
reduction of 4-NP did not perform well under the condition, even with a
large excess amount of NaBH 4 , in the absence of the catalyst.

15.4 Novel Chemical Synthesis Routes

Chemical synthesis has been very useful in the synthesis of a wide range of
nanostructured materials, including high-surface-area transition metals,
alloys, carbides, oxides and colloids. It is well established that various fac-
tors, such as availability and cost of the required reagents; reproducibility
of a particular route; necessary characteristics required in the i nal prod-
uct; and the cost of the process, determines the choice of the preparative
route. h e chemical preparative routes that have been investigated so far
for the preparation of nanosize metal-doped titanium dioxide photocata-
lyst can be categorized under two broad headings of:

a. Vapor-phase or Gas-phase reaction
b. Solution processing technique