Energy density and IR spectra of polyaniline synthesized electrochemically in the solutions of strong acids

The electrochemical polymerization of aniline in fluoboric acid, hydrochloric acid, perchloric acid, sulphuric acid and nitric acid was carried out at a constant potential of 0.75 V (vs. SCE). The conductivity of polyaniline synthesized in fluoboric acid is the largest and that synthesized in nitric acid is the smallest among the above acids used for the polymerization of aniline. The conductivity of polyaniline synthesized in sulphuric acid is a little higher than that synthesized in nitric acid. Based on the results from the constant current charge–discharge process, the order of the energy density of polyaniline synthesized in the various acids is as follows: EHBF4>EHCl>EHClO4>EH2SO4>EHNO3. This result is similar to the redox charge of polyaniline from the cyclic voltammograms of polyaniline obtained in various acids at the same polymerization charge. The absorption peaks of BF4−, ClO4−, NO3− and SO42− doped in polyaniline are observed in the IR spectra. There is a relationship between the relative intensity of the absorption peaks of the benzene and quinone rings to that of the doped anion, i.e., the relative intensity of absorption peaks in IR spectra decreases with increasing conductivity of polyaniline.