Theoretical prediction and experimental study on catalytic mechanism of incorporated Ni for hydrogen absorption of Mg

Transition metals, including Ni, show good catalytic activity in the hydrogen storage reaction of Mg. In the present paper, first-principles calculation is performed to predict and analyze the hydriding reaction of Ni-incorporated Mg and experimental study is used to verify the accuracy of the forecast. Theoretical studies show that the hydriding reaction of Ni-incorporated Mg is a diffusion-controlled process. With Ni incorporation, the energy barrier of H-2 dissociation is significantly decreased and the diffusion becomes the limiting step. Experimental studies confirm the results of theoretical studies. Besides, the material with Ni incorporation shows excellent activation performance and rapid absorption rates, leading to a high hydrogen content of 4.1 wt% in 60 s under 240 degrees C 3.0 MPa H-2 and a low activation energy of 56.1 kJ mol(-1) versus 0.4 wt% and 73.5 kJ mol(-1) for the material without Ni incorporation. Atomic Ni only plays a role of catalyst. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.