Seminar
Novel Mg-based Amorphous Alloys and Nanocomposites Induced from Amorphous Alloys for Hydrogen Storage
Speaker:Prof. Huai-Jun LIN
Associate Professor of Institute of Advanced Wear & Corrosion Resistance and Functional Materials
Jinan University
China
Date & Time:29 Nov 2019 (Friday) 11:00 - 12:00
Venue:E12-G003
Organized by:Department of Physics and Chemistry

Abstract

MgH2 has been widely considered as a promising candidate for hydrogen storage because it stores 7.6 wt% of hydrogen, however thermodynamics and kinetics for hydrogen absorption and desorption are not well satisfied. Abundant efforts have been devoted to prepare nanostructured Mg-based materials with enhanced hydrogen storage. Although kinetics improvements could be well achieved, thermodynamics issues are remained in Mg-based hydrogen storage materials.

We attempted to prepare novel Mg-based amorphous alloys for hydrogen storage applications. The results could be summarized as follows: (1) A hydrogen-induced glass-to-glass transition in Mg-Ce-Ni amorphous alloys with a storage capacity of 5 wt%-H is reported. The hydrogen storage capacity of amorphous hydrides is obviously higher than that of their crystalline counterparts owing to the free volume and disordered atomic structure associated with glasses. (2) The dehydrogenation temperature of the amorphous hydrides can be efficiently tuned as it shows a close relationship with the enthalpy of mixing between the alloying element and hydrogen. (3) Further study on the five-component Mg60Ce10Ni20Cu5X5 (X = Co, Zn) amorphous alloys shows that addition of Co greatly improves the hydrogenation kinetics and capacity, indicating that geometry issue is not a key factor on influencing the hydrogenation properties of the studied Mg-based amorphous alloys. (4) Similarly, minor alloying addition of Ag improves the hydrogen storage capacity and reduces the dehydrogenation temperature of the amorphous Mg65Cu25Y10 alloy. (5), High-pressure torsion (HPT) is applied to reduce the hydrogenation temperature and improve the hydrogenation kinetics of Mg-based amorphous alloy, which is due to the introduction of nanoglasses regions and interfaces among them providing abundant pathways for fast hydrogenation.

Moreover, hydrogenation treatment of the Mg-based amorphous alloys at temperature above the crystallization temperatures will lead to the formation of hydrides nanocomposites consisting of MgH2, Mg2NiH4 and so on. Hydrogen storage properties of the nanocomposites could be well tuned by designing the chemical compositions and phase structures, by controlling the hydrogen activation treatments, and by designing subsequent oxidation treatment upon the nano-hydrides composites etc.

Biography

Prof. Huai-Jun Lin serves as associate professor in Jinan University, Guangzhou, China from 2017. During his PhD study, he obtained a CSC scholar and studied as a visiting student in Kyushu University, Japan from 2013 to 2014. After completing his Ph.D. degree in Materials Science and Engineering from South China University of Technology, China in 2014, he worked in Kyushu University as a Postdoctoral fellow from 2015 to 2016. His research interests include hydrogen storage materials, functional applications of amorphous alloys and battery etc.