42
K. Illath et al.
Fig. 5 Shape evolution with reaction time in the solvothermal process; TEM images of a initial
Ag nanocubes, after a reaction time of b 6 h and c 12 h, d schematic illustration of a possible
mechanism of shape evolution. Republished with permission of the Royal Society of Chemistry,
from Ref. [40]
solvothermal approach [43, 46–54]. Ligands that bind with metal cations can reduce
its redox potential and make their reduction reaction very difficult. Some ligands
can change their redox potential and can effectively contribute to the formation of
metallic nanocrystals. Depends on the reactions, ligands serve as a capping agent
to stabilize some facets or etching agents. In solvothermal synthesis, facet specific
capping agents are used to expose distinct facets. These capping agents are usually
counter ions present in the ionic species, solvents, precursors, polymers, organic
molecules, surfactants, thermal decomposition products, etc. [37]. Amine and glycine
are commonly employed surface controller or facet specific capping agents in synthesizing Pt nanocrystals with high index facets. It has been found that the addition of 1octylamine leads to multipod Pt NPs with dominant {211} surfaces, while formaldehyde gives concave cubes with {411} surface exposed. IR spectroscopic investigation of synthesized Pt NPs reveals that pure amine can adsorb on monoatomic step
edges consisting of (111) terrace and (100) steps, results in the formation of {211}
exposed surface. In the case of formaldehyde, by-product stabilizes (100) terrace,
which enlarges it and leads to exposing {411} surface. Without formaldehyde, at the
beginning of synthesis, formed nuclei clusters grow quickly along <111> direction
with {211} facet exposed, which results in multipod nanoclusters. In the presence of
K. Illath et al.
Fig. 5 Shape evolution with reaction time in the solvothermal process; TEM images of a initial
Ag nanocubes, after a reaction time of b 6 h and c 12 h, d schematic illustration of a possible
mechanism of shape evolution. Republished with permission of the Royal Society of Chemistry,
from Ref. [40]
solvothermal approach [43, 46–54]. Ligands that bind with metal cations can reduce
its redox potential and make their reduction reaction very difficult. Some ligands
can change their redox potential and can effectively contribute to the formation of
metallic nanocrystals. Depends on the reactions, ligands serve as a capping agent
to stabilize some facets or etching agents. In solvothermal synthesis, facet specific
capping agents are used to expose distinct facets. These capping agents are usually
counter ions present in the ionic species, solvents, precursors, polymers, organic
molecules, surfactants, thermal decomposition products, etc. [37]. Amine and glycine
are commonly employed surface controller or facet specific capping agents in synthesizing Pt nanocrystals with high index facets. It has been found that the addition of 1octylamine leads to multipod Pt NPs with dominant {211} surfaces, while formaldehyde gives concave cubes with {411} surface exposed. IR spectroscopic investigation of synthesized Pt NPs reveals that pure amine can adsorb on monoatomic step
edges consisting of (111) terrace and (100) steps, results in the formation of {211}
exposed surface. In the case of formaldehyde, by-product stabilizes (100) terrace,
which enlarges it and leads to exposing {411} surface. Without formaldehyde, at the
beginning of synthesis, formed nuclei clusters grow quickly along <111> direction
with {211} facet exposed, which results in multipod nanoclusters. In the presence of