Stability and hydrogen adsorption properties of Mg/Mg2Ni interface: A first principles study

The stability and hydrogen adsorption behaviors of Mg/Mg2Ni interface were studied by first principles calculations. Results demonstrated that the interaction between Ni (from Mg2Ni compound) and Mg (from Mg metal) is the key factor stabilizing the interface, and the interface provides a medium to capture hydrogen atoms originating from the accumulation of electrons in the interface zone by the formation of the interface. Hydrogen atoms adsorbed in the interface zone tend to form covalent bonds with metal atoms (Ni and Mg atoms), which deliver negative adsorption energies in the range of -0.831 to -0.019 eV for most possible adsorption sites. However, the strength of the H-metal bonds depends on the environment the H located. The present study illustrates that the Mg/Mg2Ni layered structure could be a potential medium for reversible de/hydrogenation processes. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.