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Summary Polyaniline (PANI) based composites and multilayers as well as porphyrin derivatives have been previously reported as efficient anti-corrosion coatings. In our studies, 5,10,15,20-tetra(4-methylphenyl)-21H,23H-porphyrin (TMP) was adsorbed on carbon steel surface before PANI electrodeposition, in order to improve the corrosion protection of PANI films on steel. The corrosion behavior of the TMP-PANI bilayer carbon steel modified electrodes was investigated in 0.1 M H2SO4 solution using electrochemical tehniques. It was found that TMP-PANI coatings can provide a good protection against carbon steel corrosion. The corrosion rate for the composite coated steel was significantly lower than that of the bare steel, and exhibited an inhibition efficiency of ∼80%.

Detection of biologic compounds in particular dopamine is usually based on the complexation between boronic acid groups and diols. For this reason the development of new sensors based on direct monitoring of boronic acid–diol complexation is attractive. A measurable electric response due to a change in the dopamine concentration can be achieved on electrodes modified with boronic groups. In this work a modified electrode has been obtained by electropolymerization of 3-aminophenylboronic acid in aqueous solutions on a preformed polyaniline layer electrochemically deposited on smooth and skeleton nickel electrodes. The modified electrodes have been tested as impedimetric sensors for the detection of dopamine in aqueous phosphate buffer at pH = 7.4. Both sensors gave a linear response for dopamine concentrations between 10−5 and 10−10 mol L−1. Poly(3-aminophenylboronic acid) modified skeleton nickel electrode has the advantage of an increased specific surface area, that lead to a high density of boronic acid groups and hence to a better sensitivity.