Formation of Mg2Ni with enhanced kinetics: Using MgH2 instead of Mg as a starting material

At a temperature over the decomposition point (375 °C) of MgH2, the formation of Mg2Ni is greatly enhanced from the 2MgH2+Ni system, as compared to the 2Mg+Ni system. In support of this finding, in-situ observation of X-ray absorption fine structure of the two systems indicates that MgNi bonds form faster in the 2MgH2+Ni system than in the 2Mg+Ni system. Furthermore, theoretical modeling also shows that Mg atoms are readily released from MgH2 using much less energy and thus are more available to react with Ni once the dehydrogenation of MgH2 occurs, as compared to normal Mg.

Graphical AbstractThe formation of Mg2Ni is greatly enhanced by using MgH2 instead of Mg at a temperature higher than the MgH2 decomposition point.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► A new and efficient synthesis of Mg-based compounds at a reduced temperature. ► Mg2Ni formation is enhanced by using MgH2 instead of Mg as a starting material. ► XAFS results show that MgNi bonds are formed faster in 4MgH2+Ni than in 4Mg+Ni. ► DFT calculations show that Mg atoms are released from MgH2 more readily than from Mg. ► Mg formed by MgH2 dehydrogenation is more available to react with Ni than normal Mg.