The hydrogen evolution reaction on nickel-polyaniline composite electrodes

The electrolytic codeposition of nickel composite coatings with different amounts of polyaniline particles (PAni) was used to produce electrodes for the catalytic hydrogen evolution reaction (HER). The electrodes produced were imaged by scanning electron microscopy, and their catalytic activities for HER were determined by linear Tafel polarization and electrochemical impedance spectroscopy (EIS) in a 0.5 M H₂SO₄ solution. The electron micrographs showed that the amount of exposed polyaniline surface was directly related to the polyaniline concentration in the solution used for the electrolytic codeposition. The linear Tafel polarizations indicated that the HER was limited by the Volmer step, and the EIS measurements showed that the presence of PAni on the electrode surface affected the HER. Electrodes with higher composite contents exhibited enhanced catalytic activity.