Hydrogen Absorption Estimation on Pd Electrodes from Electrochemical Noise Measurements in Single-Compartment Cells

This paper is aimed at investigating the possibility of detecting and estimating hydrogen absorption on standard cylindrical electrodes in single-compartment electrochemical cells, to avoid classical measurements with membrane-shaped samples in double-compartment cells that cannot be carried out in many practical situations. This was achieved by comparing the hydrogen bubble evolution on a strongly hydrogen-absorbing metal (Pd) and a nonabsorbing one (Pt) from electrochemical noise measurements at high charging current densities between -25 and -125 mA/cm². The bubble evolution characteristic parameters (detachment mean radius and mean rate) were derived from the power spectral density of the electrolyte resistance fluctuations. The difference in the mean volume of gas evolved per time unit on Pt and Pd was used to derive the hydrogen absorption flux in Pd. A good agreement was obtained with values reported in literature for high cathodic current densities, that is, in the presence of important β-PdHλ phase concentration.