The investigation on the mechanism of electrochemical hydrogen storage in sandwich nickel foam/palladium/carbon nanofibers electrodes

The kinetics of the process of reversible hydrogen sorption occurring in/on the nickel foam/palladium/carbon nanofibers (Ni/Pd/CNFs) electrodes is examined. It was shown that the hydrogen sorption/desorption properties for palladium can be altered after Pd layer is sandwiched between nickel foam and carbon nanofibers (CNF) layers. The layered Ni/Pd/CNFs electrodes were prepared by a two-step method consisting of chemical deposition of a very thin palladium layer on the Ni foam surface to form Ni/Pd electrodes followed by coating the Pd surface with the CNF layer by the CVD method. The process of hydrogen sorption/desorption into/from Ni/Pd as well as Ni/Pd/CNF electrodes was examined in alkaline electrolyte using the cyclic voltammetry method. The presence of CNF layer on the Pd surface exerts a great influence on the mechanism of the anodic desorption of hydrogen. A new anodic peak of hydrogen desorption revealed for Ni/Pd/CNF electrodes is ascribed to hydrogen storage in CNF phase. The CV measurements showed distinct differences between the rate of hydrogen release from the palladium and carbon phase.