Electrochemical impedance study of the kinetics of hydrogen evolution at a rough palladium electrode in acidic solution

Hydrogen evolution reaction (HER) was studied over a rough rotating disk palladium electrode in 0.1 M sulfuric acid using steady-state polarization current measurements and electrochemical impedance spectroscopy (EIS). Among all the applied potentials, up to − 0.074 V, two semicircles were found on the complex plane plots, which were attributed to the HER. Surface roughness factor, Rf = 23, was determined from the double-layer capacitance. The Tafel slope was − 0.097 V dec− 1 and the value of the intrinsic exchange current density was 0.22 mA cm− 2. The double layer capacitance, charge transfer resistance, adsorption resistance, and pseudocapacitance as functions of potential were also determined from the EIS results. The HER proceeds through the Volmer-Heyrovsky mechanism.