In this paper, A(2)ZnH(4) (A = K, Rb and Cs) have been synthesized for the first time by a new approach involving in two-step reactions, in which the target samples can be produced under mild conditions (160 degrees C for 4 h). What's more, the additive effects of A(2)ZnH(4) on the hydrogen storage properties of 2LiH-Mg(NH2)(2) composite have been investigated systematically. Experimental results show that K2ZnH4 has the best comprehensive modification effects among these hydrides. The 2LiH-Mg(NH2)(2)-0.1K(2)ZnH(4) sample shifts dehydrogenation peak temperature downwards by ca. 30 degrees C as compared to the pristine sample. In addition, about 70% extent of the theoretical hydrogen is able to desorb from the 0.1K(2)ZnH(4) doped sample at 140 degrees C within 2 h, however, only 20% extent of hydrogen is liberated from the pure sample under the same conditions. The improved desorption kinetics is indicated by the reduced dehydrogenation activation energy (Ea), the Ea of the 0.1K(2)ZnH(4) doped sample is around 68 +/- 1.0 kJ mol(-1) which is 28% lower than that of the pristine one. Furthermore, the dehydrogenation mechanism of the K2(Z)nH(4) doped sample has been proposed. (c) 2020 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.
Mild-condition synthesis of A(2)ZnH(4) (A = K, Rb, Cs) and their effects on the hydrogen storage properties of 2LiH-Mg(NH2)(2)
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