Effect of TiO2 nanoparticles on polyaniline films electropolymerized at different pH.
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2016
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In this work hybrids of titanium nanoparticles and polyaniline are
obtained by pulsed electrodeposition at different pH (1.5, 3.9 and 5.9) and
characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy,
cyclic voltammetry, ultraviolet−visible, and Raman spectroscopies. We found that
films deposited at pH 5.9 with nanoparticles incorporation are composed of
emeraldine meanwhile films without nanoparticles are composed of pernigraniline.
As a result, films deposited with nanoparticles incorporation present conductivity 6
times higher than that of films deposited without nanoparticles. Films deposited at
pH 3.9 with or without nanoparticles incorporation are both made of pernigraniline.
Even though films with nanoparticles incorporation still present higher conductivity.
To explain such a result, we performed first-principles calculations on polyaniline/
TiO2 interface. The calculations predict a metallic polyaniline/TiO2 interface in spite
of polyaniline and TiO2 being semiconductors. At pH 1.5, the presence of
nanoparticles has negligible effect on films characteristics. We believe that at low pH
(pH 1.5) H atoms tend to bind TiO2 surface resulting in positively charged nanoparticles, which are further screened by SO4
−2
anions. Such a screening layer prevents the physical contact between nanoparticles and polyaniline monomers diminishing the
effects of nanoparticle presence.
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LEITE FILHO, V. F. et al. Effect of TiO2 nanoparticles on polyaniline films electropolymerized at different pH. Journal of Physical Chemistry. C, v. 120, p. 14977-14983, 2016. Disponível em: <http://pubs.acs.org/doi/abs/10.1021/acs.jpcc.6b04919>. Acesso em: 16 jan. 2018.