Electropolymerization of ortho-phenylenediamine. Structural characterisation of the resulting polymer film and its interfacial capacitive behaviour

•Structural characterization of non conductive electropolymerized oPD thin films.•Gallic acid capacitive sensing.•Impedance spectroscopy.•Raman spectra.•DFT calculations.

The physico-chemical characteristics of thin poly-(ortho-phenylenediamine) (PPD) films, obtained by electrochemical oxidation of the relevant monomer, are investigated using electrochemical, morphological and spectroscopic techniques. In particular, cyclic voltammetry and electrochemical impedance spectroscopy (EIS) techniques are used to collect information concerning the redox, conductivity and double layer capacitance properties of the PPD film. AFM imaging and Raman spectroscopy results are exploited to characterize the film structure. In this respect, Raman spectra of two possible PPD oligomers are calculated at the B3LYP/6-311G** level of the theory.