3. Results and discussion
Metal nanoparticles show a characteristic surface plasmon band
as measured by UV/vis spectrometer [24,25]. Generally surface
plasmon in nanoparticles is caused by the fluctuations of electron
density surrounded in nano-sized metal, and dependent on the size
and the shape of nanoparticles [26]. Fig. 1 shows the absorption
spectra of gold nanoparticles (GNPs) and Au-MWNT nanocomposites.
The same absorption bands of ∼525 nm present that the
GNPs in these Au-MWNTs have the same structural characteristics,
and the electrostatic intermolecular interaction between GNPs and
MWNTs dispersed in water is too small to give an effect on the fluctuation
of electron density restricted in a nano-sized gold particle.
A little broadening of the band shapes might be caused by the weak
interaction of GNPs and MWNTs.
The detailed morphologies of Au-MWNT nanocomposites have
investigated by TEM images as shown in Fig. 2. Using the welldefined
GNPs [see Fig. 2(a)] with sizes of ∼5 nm, we have prepared
three nanocomposites of Au-MWNT(SDS), Au-MWNT(PSS) and
Au-MWNT(PVP), in which SDS, PSS, and PVP in brackets indi