MgNi/Pd multilayer hydrogen storage thin films prepared by dc magnetron sputtering

Abstract

MgNi/Pd multilayer thin films were deposited on Ni substrate by direct current (dc) magnetron sputtering using a dual-target, each MgNi layer being 40 nm and each Pd layer being 16 nm in thickness. The total thickness of the MgNi/Pd multilayer thin film is about 1.7 m. X-ray diffraction and scanning electron microscopy analysis revealed that the microstructure of the MgNi layer is amorphous and/or nanocrystalline and that the microstructure of the Pd layer is fine grained crystalline with no preferential orientation. A pressure-composition-isotherm (PCI) measurement of films proved that the hydrogen absorption content reached to 4.6 mass% at room temperature and hydrogen desorption reached 3.4 mass% hydrogen. The deposited MgNi/Pd multilayer thin films show an interesting behavior of discharge capacity with a maximal value of 505 mAh/g.Hydrogen storage materials are one of the important key materials for the future clean energy systems. Due to the high storage capacity of the hydride phase, nearly 7.6 wt.% of hydrogen reacts with Mg to form MgH 2 and nearly 3.6 wt.% of hydrogen reacts with Mg 2 Ni to form Mg 2 NiH 4 in a reversible reaction, Mg-based materials have attracted extensive attention for application in the hydrogen storage technology [1][2][3][4][5][6]. Unfortunately, the hydride phase of Mg-based materials is very stable and shows poor hydrogen absorption and desorption kinetics even at high temperature. In the past few years, substantial improvement in the hydrogen absorption and desorption kinetics have been achieved by several different methods [7][8][9][10][11]. The most effective methods realized so far are: (1) structural refinement of the material [1,2] and (2) the addition of proper catalysts [3][4][5][6][7][8][9][10][11], which demonstrate the promising performance of nanocrystalline and amorphous magnesium-based alloys as hydrogen storage materials and metal hydride (MH) electrode for Ni-MH batteries. Paillier et al. [12] have reported the fabrication on MgNi-based

Mg3Mm compound based hydrogen storage materials

“…It can be seen from the values of S and r that the fitting is in excellent agreement with the experiment data. This result confirms that the hydriding reaction of the Mg 3 Mm alloy obeys the nucleation and growth mechanism, which is similar to other metal hydride [7]. However, different m values indicate different rate controlling step of nucleation and growth reaction.…”

“…However, the kinetic properties, hydrogen absorption/desorption temperature and pressure of dehydriding in those materials are not suitable for practical application yet. In order to improve the kinetic properties of Mg based alloys, different methods, such as alloying element substitution [1][2][3], catalysts addition [4,5], surface modification [6] and non-equilibrium microstructure formation [7][8][9] have been applied. Although many new results have been reported, the kinetics properties for those materials are still a key problem to be solved.…”

Investigation of interfaces in Mg/Nb multilayer thin films

“…Remarkable enhancement of the hydrogen sorption kinetics in the Mg/Pd thin films has been reported in other works, which used different thin films preparation and hydrogen loading conditions [10,11]. Moreover, other additives have been added to Mg-based thin films for improving their hydrogen sorption kinetic and thermodynamic properties, such as Cu [12], Ti [9], Mg-Ti-Fe [13], and Ni [14,15].…”

Mg-Based Thin Films as Model Systems in the Search for Optimal Hydrogen Storage Materials

“…Furthermore, the PES (Photoelectron Spectroscopy) demonstrated that no Mg segregation or desorption occurs when hydrogen is desorbed from the film, rendering the system reversible. The PCI measurement of amorphous MgNi/Pd multilayer thin films deposited on Ni substrate by magnetron sputtering revealed that up to 4.6 wt% of hydrogen can be loaded to the films at room temperature [75]. Approximately the same, reversible hydrogen content of 4.45 wt% at 224 °C has been obtained for the 1160 nm thick Mg2.9Ni film [76].…”