The enhanced de/re-hydrogenation performances of LiNa2AlH6 combined with two-dimension lamellar Ti3C2

摘要

In the present work, two-dimension lamellar Ti3C2 was employed as additive of LiNa2AlH6. Volumetric dehydrogenation results informed that the onset dehydrogenation temperature of the ball milled LiNa2AlH6 + 5 wt% Ti3C2 sample was lowered by 68 K from that of pristine LiNa2AlH6. Isothermal pressure-composition (P-C-I)curves and van't Hoff plots demonstrated that the dehydrogenation enthalpy value (61 kJ mol H(2)(-1)A) of LiNa2AlH6 + 5 wt% Ti3C2 was significantly reduced from the pristine LiNa2AlH6 (68 kJ mol H(2)(-1)A). By means of XPS analyses, it can be revealed that the destabilization of LiNa2AlH6 should be resulted from the involvement of Ti and the yield of unidentified Ti3+ species. Furthermore, it can be concluded that the lowering of dehydrogenation temperature was merely due to the thermal destabilization of LiNa2AlH6 by Ti3C2, since Ti3C2 hardly improved the dehydrogenation kinetics of LiNa2AlH6 and reduced its activation energy. However, hydrogenation kinetics was slightly enhanced from the released products of LiNa2AlH6 + 5 wt% Ti3C2. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.