February: Sammy Lap Ip Chan, "Preparation and diffusion of hydrogen in Mg2Ni: A first principles investigation"

February: Sammy Lap Ip Chan, "Preparation and diffusion of hydrogen in Mg2Ni: A first principles investigation"

Pathways for hydrogen to diffuse in a promising hydrogen storage alloy:  Mg2Ni

The low cost of magnesium and superior catalytic performance of nickel make Mg2Ni a promising hydrogen storage material. After hydrogenation, it transforms into Mg2NiH4 with a relatively high hydrogen storage capacity of 3.6 wt%. First-principles calculations have been used to study the hydrogen adsorption and diffusion in both hexagonal Mg2Ni surface and bulk Mg2Ni, and the hydrogen diffusion rate in bulk Mg2Ni is evaluated. The results show hydrogen diffusion from Ni-Ni bridge sites to the most nearby Mg-Ni bridges site (e.g. site 1 to site 4 in the following diagram) is energetically more favorable than the other paths, and contribute to the long range diffusion of hydrogen in the matrix. The mechanisms of hydrogen diffusion in Mg2Ni established in this work provide vital information on the phase transformation induced by hydrogen in atomic scale. According to such mechanisms, the hydrogen-diffusion-controlled properties of Mg2Ni alloy can be explained or predicted.

Read the full article, as published in the International Journal of Hydrogen Energy (Volume 42, Issue 5, 2 February 2017, pp 3097-3105).