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

•Hydrogen evolution reaction was studied at Pd in 0.1 M H2SO4 using steady-state and impedance measurements•Reproducible results were obtained on rough hanging meniscus rotating disk electrode•Two kinetic semicircles were observed on the complex plane plots•Measurements were possible in the overpotential range up to − 0.074 V•Volmer-Heyrovsky mechanism for the HER is proposed

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.

Graphical abstractDownload high-res image (100KB)Download full-size image