Electrochemical properties of polyaniline composite electrodes prepared by in-situ polymerization in titanium dioxide dispersed aqueous solution

Polyaniline (PANI)/titanium dioxide (TiO ₂) composites were prepared by a chemical oxidation polymerization. The composites were prepared with various amount of TiO ₂ to find a relation between electrochemical properties of composites and compositions of TiO ₂ and PANI in the composites. PANI/TiO ₂ composites which had PANI as a shell and TiO ₂ as a core part of the composites were successfully synthesized. Fiber-like PANI was also observed within the composites. The synthesis was explained as two stages of polymerization. First stage is a polymerization reaction occurred by a strong oxidative potential of TiO ₂. Second stage is started by adding ammonium peroxydisulfate in reaction solution. Diameters of aggregations of the composites increased with the added amounts of TiO ₂. The composite prepared with 10 wt.% of TiO ₂ per aniline monomer weight showed the highest capacitance of 784 F g ^-1 among the prepared composites. But the composites prepared with excess amounts of TiO ₂ showed lower capacitance than the highest one. The lower capacitances of the composites prepared with excess amounts of TiO ₂ was considered as related with the diameters of the aggregations. The composites prepared with excess amounts of TiO ₂ had large diameters for the aggregations. The TiO ₂ particles in the core of composites that had large diameter are hard to participate in electrochemical reaction due to a long pathway from electrolyte to TiO ₂ core and a blocking effect by outer TiO ₂ particles.