Improvement of desorption performance of Mg(BH_4)_2 by two-dimensional Ti_3C_2 MXene addition

摘要

Magnesium borohydride (Mg(BH4)(2)) is an attractive materials for solid-state hydrogen storage due to its high hydrogen content (14.9 wt%). In the present work, the dehydrogenation performance of Mg(BH4)(2) by adding different amounts (10, 20, 40, 60 wt%) of two-dimensional layered Ti3C2 MXene is studied. The Mg(BH4)(2)-40 wt% Ti3C2 composite releases 7.5 wt% hydrogen at 260 degrees C, whereas the pristine Mg(BH4)(2) only releases 2.9 wt% hydrogen under identical conditions, and the onset desorption temperature decreases from 210 degrees C to a relative lower temperature of 82 degrees C. The special layered structure of Ti3C2 MXene and fluorine plays an important role in dehydrogenation process especially at temperatures below 200 degrees C. The main dehydrogenation reaction is divided into two steps, and activation energy of the Mg(BH4)(2)-40 wt% Ti3C2 composite is 151.3 kJ mol(-1) and 178.0 kJ mol(-1), respectively, which is much lower than that of pure Mg(BH4)(2). (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.