Superior hydrogen storage and electrochemical properties of Mg-La-Pd trilayer films at room temperature

A series of Mg-La-Pd trilayer films (La = 0.5-9 nm) have been prepared by magnetron sputtering method. When the thickness of La layer is larger than 3 nm, the distribution of La element becomes homogeneous. The hydrogen storage properties of the films under 0.1 MPa H-2 and at 298 K are investigated by measuring their resistance and optical transmittance during the hydrogenation. The hydrogenation of the La 3 nm film saturates within 14 s and possesses the fastest absorption kinetics compared with other Mg-La-Pd films. The further increase of La thickness decreases the hydrogenation rate due to the decreased hydrogen diffusion rate through this layer. The La 3 nm film also exhibits the fast hydrogen desorption rate in air at room temperature. It releases 80% of hydrogen within 60 min. The electrochemical properties of the Mg-La-Pd films have been carried out in 6 M KOH with a three-electrode cell. Among these films, the La 3 nm film possesses the largest anodic area and anodic peak current, as well as the highest maximum discharge capacity of 377.8 mAh g(-1). (C) 2014 Elsevier B.V. All rights reserved.