Hydrogen storage in multi-walled carbon nanotubes decorated with palladium nanoparticles using laser ablation/chemical reduction methods

Hydrogen storage properties of multi-walled carbon nanotubes (MWCNTs) decorated by palladium nanoparticles (Pd NPs) are investigated using laser ablation and chemical reduction methods, revealing great differences between the two techniques. In the case of laser ablation, the hydrogen uptake is elevated with the Pd content up to a certain value and then undergoes a notable drop, whereas the hydrogen content linearly scales up with the Pd loading during the chemical reduction method. When the Pd loading is low, the storage capacity of the laser treated samples is higher than those decorated via the other technique of interest. During laser ablation, the larger Pd content is accompanied by plentiful pore formation, leading to larger pore sizes at higher doses, which seriously reduces the hydrogen uptake. Moreover, the desorption temperature of hydrogen notably increases in terms of Pd loading. In comparison, the laser ablation method undergoes a relatively smaller desorption temperature, mainly due to the larger pore size/volume.