Molecular Dynamics Investigation into the Hydrogen Adsorption Mechanism of the Magnesium-Based Material 2Mg-Fe Mixture

Mg2FeH6, a potential hydrogen storage medium with the largest volumetric hydrogen capacity known, is mostly obtained by reacting the 2Mg-Fe mixture with hydrogen through mechanical alloying methods. However, these mechanical alloying methods for generating Mg2FeH6 are inconvenient in operation, and the mechanism of formation of Mg2FeH(6) behind these methods is not clear so far. In this study, through molecular dynamics simulations, the microscopic process of the chemical reaction between the 2Mg-Fe mixture and hydrogen to produce Mg2FeH6 was investigated to clarify the mechanism of hydrogen adsorption by the 2Mg-Fe mixture. By analyzing the changes in bond energy and potential energy of the system, as well as the atomic trajectory, the breaking and re-formation of chemical bonds are clarified, which indicates the microscopic mechanism of hydrogen adsorption by the 2Mg-Fe mixture. In addition, the influences of temperature and pressure on the hydrogen adsorption process of the 2Mg-Fe mixture were studied. It was shown that increasing the pressure has a positive effect on the hydrogen storage capacity of the 2Mg-Fe mixture, while increasing temperature beyond 300 & DEG;C has little effect. Especially, the mass hydrogen storage capacity of the 2Mg-Fe mixture at 10 MPa and 400 ? was found to reach its theoretical hydrogen storage capacity of 5.5 wt %.