Electrochemical sorption of hydrogen in exfoliated graphite/nickel/palladium composite

The aim of the present work was to examine the processes of hydrogen sorption/desorption occurring in alkaline solution for electrodes made of EG/Ni/Pd (exfoliated graphite/nickel/palladium) composite. The electrochemical investigations were carried out using cyclic voltammetry technique accompanied by the potentiostatic polarization of electrode material at negative potential. To saturate the electrode with hydrogen, when an electrode reached the potential of −1.2 V, the potential was stopped for a chosen time. After that the potential scanning was continued. Anodic charge insignificantly increases with increasing the hydrogen sorption duration, whereas the changes in shape as well as in location of anodic peaks noted in response to the cathodic reactions of hydrogen sorption are much more pronounced. It indicates that mechanism and kinetics of the oxidation/desorption processes are altered due to increase in sorption time. The SEM (scanning electron microscopy) equipped with EDS (energy dispersive spectrometer) detector and XRD (X-ray diffraction) analysis were used to characterize the investigated composite material.