Abstract:
Electrochemical polymerization of aniline occur on Pt, Ni and Stainless
steel at O.6V, I.05V and O.85V respectively. Oxidative dissolution of Cu
and Co at-O.15V and ---{).2Vbefore polymerization of aniline occur on
them. Good PANI film is formed on Pt and stainless steel but it does not
adhere strongly on Ni surface. Electrodepostion of Cu, Ni and Co occurs
on PANI film at -0.33V,-1.30V and -1.IOV vs. SCE respectively.
In the SEM study PANI deposits on stainless steel as continuos film. Some
craters are found in PANI film. At high magnification, PANI film appears
porous with size of micrometer range or so.
The SEM analysis confIrmSthe deposition of Cll, Ni and Co on PANI film.
Visual examination also reveals brick-red Cu over whole PANI-film. Cu is
deposited both in craters as well as in the surface of PANI film. Both at
low and high magnification, the morphology of Cu deposition is dendritic
cluster which looks dense forest like structure. Ni deposits discreetly some
places as a cluster of hemispherical nucleus forms island. Co deposits in
some craters of PANI. At high magnification a few isolated hemispherical
bright Co nuclei are visible.
From the IR spectral analysis of PANI and PANI-Metal samples, it is
revealed that there has not been any remarkable change of PANI structure
as a result of metal deposition. During the metal deposition PANI is
reduced. The reduced PANt-Metal sample shows a peak at -1250cm-1.
This peak is not found in PANt which is consistent with secondary
aromatic amine converted by the reduction from imine or oxidized imine
oramme
In the UV-Vis. spectra, PANI shows lower band gap than PANI-Metals.
The band gap obtained for PANI, PANI-Cu, PANI-Ni, PANI-Co are
3.76eV, 3.86eV, 3.80eV, 3.83eV respectively. Therefor their conductivity
order may be expected to be as: PANI > PANI-Ni > PANI-Co> PANI-Cu.
lt may be anticipated that polaron and bi-polaron sites in the PANI do not
exist due to reduction during metal deposition. Therefore, decrease the
conductivity in PANI-Metal samples.
PANI behaves like metal rather than semiconductor. The measured
conductivity order is found as: PANI > PANI-Cu > PANI-Ni. The
dendritic continuation of Cu deposition on all over PANI film may
contribute the increase of conductivity than PANI-Ni where Ni is
deposited discreetly some places on PANI film.
The X-ray diffraction pattern of PANI sample shows a diffused peak at
29value of 12.2°-12.5°.AIIPANI Metal samples(e.g., PANI-Cu, PANI-Ni,
PANI-Co) show same peak at that range which conclude that the order of
array of polymer chain i.e., the crystaIlianity of polymer matrix is much
poor to amorphous. Thus, it could not be anticipated the crystaIlianity of
PANI-Cu, PANI-Ni and PANI-Co samples
