Effect of catalytic Ni coating with different depositing time on the hydrogen storage properties of ZrCo alloy

In this paper, ZrCo alloy was prepared by vacuum arc-melting method and further modified with Ni coating via electroless plating method with different depositing time 10-40 min, respectively. The effects of Ni coating on microstructures, morphology and hydrogen storage properties including kinetic property, thermodynamic behavior and cycling stability of ZrCo alloy have been investigated systematically. It is confirmed that ZrCo alloy is successfully coated with Ni particles which transform from a dispersed distribution to a uniform and compact arrangement with increasing depositing time. The improved hydrogen absorption kinetic property of Ni coated alloys is attributed to the catalyst effect of Ni which facilitates hydrogen to dissociate on alloy surface in the initial incubation. In the hydriding period, Ni coated alloys with increasing depositing time exhibit slower hydriding rate due to the thicker Ni coating which increases the resistance of hydrogen diffusion and reduces the diffusion rate. Ni coated alloy with depositing time 20 min shows superior absorption/desorption kinetic property. In addition, compared with the original alloy, the dehydrogenation temperature of Ni coated alloy with 20 min depositing time decreases, demonstrating potential for the further application in International Thermonuclear Experimental Reactor (ITER).