Superior hydrogen storage and electrochemical properties of Mg _xNi_100-x/Pd films at room temperature

The Mg_xNi_100-x films of 100 nm have been prepared by magnetron co-sputtering Mg and Ni targets, and a Pd layer of 10 nm was deposited on these films by magnetron sputtering a Pd target. Mg₂Ni and MgNi₂ are directly generated during the co-sputtering process in the Mg₈₄Ni₁₆/Pd and Mg₄₈Ni₅₂/Pd films. The hydrogen storage properties of the films under 0.1 MPa H₂ at 298 K were investigated. The hydrogenation of the Mg₈₄Ni₁₆/Pd film saturates within 45 s and exhibits the faster absorption kinetics compared with Mg₉₄Ni₆/Pd and Mg₄₈Ni₅₂/Pd films. The electrochemical properties of the Mg_xNi_100-x/Pd films were investigated in 6 M KOH with a three-electrode cell. The Mg ₈₄Ni₁₆/Pd film can be activated just at the first cycle. The maximum discharge capacity of the Mg₈₄Ni₁₆/Pd film is 482.7 mAh g^-1, the highest among these films.