Hydrogen storage in TiVCrMo and TiZrNbHf multiprinciple-element alloys and their catalytic effect upon hydrogen storage in Mg

Hydrogen storage performance of nearly equimolar alloys TiVCrMo and TiZrNbH (HEA's) was studied. The alloys were prepared by repeated arc-melting in the form of single-phase alloys and as their multiphase analogues prepared either by high-energy ball milling (HEBM) of the arc-melted ingots or by HEBM of pure elements. Besides these four-component experimental materials, also their mixtures with Mg were investigated that were prepared by HEBM with Mg (composition in both cases was Mg 10 wt % HEA). Hydrogen sorption experiments were carried out in temperature interval between 240 degrees C and 380 degrees C under hydrogen-gas pressure up to 50 bars. Kinetic curves, temperature-programmed desorption spectra and concentration-pressure isotherms were measured. It was found that activation energy of hydrogen desorption, vertical bar E-a vertical bar, for materials with Mg was significantly decreased compared to pure Mg. Hydride formation enthalpy, Delta H, observed for all the materials under study was about the same as that for pure MgH2. Hydrogen absorption capacity in pure four-component HEA's was negligible; only hydrogen surface adsorption was detected. The capacity of mixtures of HEA's with Mg was between 3.5 and 6 wt % H-2. (C) 2022 Elsevier Ltd. All rights reserved.

Automated summary

The hydrogen storage performance of nearly equimolar alloys TiVCrMo and TiZrNbH (HEA's) was investigated. It was found that the activation energy of hydrogen desorption decreased significantly when Mg was added to the materials, but the hydrogen absorption capacity remained low. The enthalpy of hydride formation for these materials was similar to that of pure MgH2.