Sensors - Hierarchical Nanostructures for Energy Devices - page 249

d n 3 r 4 n g | 4

Figure 11.1 Various hierarchical metal nanostructures: (a) Ag decorated Si/ZnO
nanotrees (adapted from ref. 12 with permission), (b) Au particle
array deposited with hierarchical surface roughness on an ITO (adapted
from ref. 14 with permission), (c) Ag nanowire array which was fabri-
cated by using the Langmuir-Blodgett technique (adapted from ref. 11
with permission), (d) Cu microtube which was made by metal de-
position (adapted from ref. 48 with permission), (e) core-shell Ag
nanowires covered by nanosheets (adapted from ref. 9 with permis-
sion), (f) silicon nanowires coated with silver nanoparticles (adapted
from ref. 13 with permission), (g) b-Ni(OH)2 nano-flowers (adapted
from ref. 10 with permission).

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SERS and an additional layer of Ag wire nanosheets. They showed the acid-
directed self-assembled hierarchical nanostructure for bimolecular de-
tection. Sarkar et al. 10 synthesized b-Ni(OH) 2 nano-flowers, which were made
with ammonia and nickel acetate by a seedless hydrothermal method as
shown in Figure 11.1(g). Tao et al. 11 adopted the Langmuir-Blodgett tech-
nique to fabricate an aligned Ag nanowire monolayer that had an excellent
packing density as shown in Figure 11.1(c).

11.3.2.2 Combination of Top-down and Bottom-up Approaches
Recent studies on hierarchical metal nanostructures have used a combin-
ation of top-down and bottom-up approaches. Basically, large area patterns