As a kind of surface-active agent, toluene-p-sulfonic acid (p-TSA) could be used to pre-disperse La₂O₃. On the other hand, p-TSA was also a protonic acid. The electric conduction of polyaniline (PANI) could be obtained by doping with it. According to these properties, PANI/La₂O₃ nanocomposite was synthesized by a chemical method. The electrical conductivity was measured by a four probe method. The nanocomposite was characterized by SEM, EDS, XRD and FT-IR. The result indicated that the electrical conductivity of PANI and PANI/La₂O₃ were 1.0 •and 1.9 S•cm^－1, the particle diameters were about 200 and 50 nm, respectively. The doping of La₂O₃ could reduce the diameter, and meanwhile did not lower the conductivity of PANI. The products were also characterized by cyclic voltammetry. The result showed that doping of La₂O₃ raised oxidative (and reductive) peak current densities and restrained the electrochemical degradation of PANI in aqueous solutions containing 0.25 to 2.00 mol•L^－1 sulfuric acid or phosphoric acid•.

Key words: PANI, La₂O₃, nanocomposite, electrical conductivity, cyclic voltammetry, electrochemistry degradation