Electrodeposition and characterization of Polyaniline films

This study describes the effects of deposition potential and deposition time on the electrodeposition of Polyaniline (PANi) films on indium tin oxide (ITO)-coated glass substrate. It was found that the aniline with 0.5M in 1M H₂SO₄ started to polymerize on ITO substrate at + 0.70 V vs Ag/AgCl. Chronoamperometry was used to deposit PANi on ITO-coated glass at three different applied potentials (ie: +0.75V, +1.0V and +1.5V) and three different deposition times (ie: 60s, 300s and 600s). The surface morphology of the PANi films was imaged by field emission scanning electron microscopy (FESEM). The films electrodeposited at different potential and different deposition time exhibit different surface morphologies. At short deposition time (60s) with constant potential of +0.75V, a thin two dimensional (2D) PANi film was deposited on the ITO and adhered strongly on the ITO surface. However, when the deposition time was prolonged longer, the microgranular and nanorod-shaped PANI particles started growing upward on the first layer (thin compact film) and finally the uppermost layer consisted of compact and dense nano-fibrillar PANi particles with few small voids. Nevertheless, the top layer was not strongly adhered on the adherent thin film. On the other hand, deposition at high potential (+1.50V) for a short time also produced a thick and dense PANi layer (dark blue in colour) was formed on the ITO surface with the presence of few voids and crevices. The electrodeposition of Polyaniline (PANi) at +1.50 V was 2.5 times faster than at +1.0V and 23 times faster than at +0.75V. The thin compact PANi film is a promising material to be used in electrochromic windows due to its good adhesion, transparency and electrochromism.