Visible-light photocatalytic degradation performances and thermal stability due to the synergetic effect of TiO2 with conductive copolymers of polyaniline and polypyrrole

Abstract

Conductive polypyrrole–polyaniline/TiO₂ nanocomposites (PPy–PANI/TiO₂) were prepared by in situ oxidative copolymerization of pyrrole and aniline monomers in the presence of TiO₂. For comparison studies, polypyrrole/TiO₂ (PPy/TiO₂) and polyaniline/TiO₂ (PANI/TiO₂) were also prepared. The samples were characterized by X-ray diffraction, transmission electron microscopy, UV-vis diffuse reflectance spectroscopy, zeta potential analysis, Fourier transform infrared spectroscopy, thermogravimetric analysis and photocurrent tests. In contrast to PPy/TiO₂ and PANI/TiO₂, PPy–PANI/TiO₂ exhibits obvious absorption in the visible-light range, and is much superior to PPy/TiO₂ and PANI/TiO₂ in thermal stability. It is found that PPy–PANI/TiO₂ performs well in the visible-light photocatalytic degradation of 4-nitrophenol. The optimized pyrrole : aniline : TiO₂ molar ratio for best performance is 0.75 : 0.25 : 100. The efficacy of PPy–PANI/TiO₂ is attributed to its conductivity, conjugated structure, as well as to the synergy amidst polypyrrole, polyaniline and TiO₂.