Effect of MWCNT (Multi-Walled Carbon Nano-Tube) Doping on Hydrogenation Kinetics of Mg-CaO Alloys.

Abstract

Magnesium hydride has a high hydrogen storage capacity (7.6 wt.%), and is cheap and lightweight, thus advantageous as a hydrogen storage alloy. However, Mg-based hydrides undergo hydrogenation/ dehydrogenation at high temperature and pressure due to their thermodynamic stability and high oxidation reactivity. Various attempts have been made to lower the reaction rate and dehydrogenation temperature by adding transition elements (e.g., Ti, Fe, Co, Ni, Ce), metal oxides, and intermetallic compounds to overcome these shortcomings. On the other hand, carbon materials have been mainly studied in the field of hydrogen storage with high specific surface area and lightweight properties; however, results show that they cannot store a large amount of hydrogen. Recently, it has been theoretically reported that carbon materials act as adsorbents in hydrogen storage. This study focuses on the hydrogenation behavior of MgHx-CaO and MgHx-CaO-MWCNT composites prepared by hydrogen-induced mechanical alloying, and investigates the properties of these composite materials.