Electrosorption of hydrogen into palladium–rhodium alloys: Part 2. Pd-rich electrodes of various thickness

Hydrogen electrosorption into Pd-rich (≥80% Pd) Pd–Rh alloy layers of various thickness has been studied in acidic solutions (0.5 M H2SO4) using cyclic voltammetry and chronoamperometry. Pd–Rh electrodes were prepared as limited volume electrodes (LVEs) by electrochemical deposition. The influence of electrode potential and alloy thickness on the amount of electrosorbed hydrogen was investigated. For the thickness range examined (0.11–1.55 μm) no distinct effect on alloy absorption properties was found. The influence of scan rate on hydrogen oxidation charge was also studied. The results obtained suggest that the layer of subsurface hydrogen in Pd–Rh alloys is much less developed than in pure Pd and direct hydrogen absorption/desorption path is more probable.