Impedance spectra of the cathodic hydrogen evolution reaction on polycrystalline rhenium

The cathodic behavior of metallic rhenium was studied potentiodynamically in acid media. The impedance spectra were analyzed to determine the behavior of the hydrogen evolution reaction (HER) on polycrystalline rhenium. Our results show that the electrocatalytic behavior of the metallic rhenium towards the HER follows the principle of Sabatier. However, during the last years, volcano plots in textbooks show that platinum and rhenium have the same performance for the HER. The literature on HERs does not consider the formation of the rhenide anion, though polarographic studies have proposed the formation of the rhenide anion. However, the impedance spectra do not support the formation of this rhenide anion. Specifically, only one single charge transfer resistance was detected in the spectra, and consequently, the HER is the unique process in this range of potentials. The features of the impedance spectra were related to the changes of the resistance of the charge transfer, which corresponds to the HER on metallic rhenium. The parameters of the Randles equivalent circuit fulfill the impedance characteristics of the HER on this metal. Copyright (c) 2016, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.