Key Takeaways & Executive Findings
- •• Electrical explosion of wires (EEW) enables synthesis of MgH2–Al composites with core–shell structures that enhance hydrogen interaction characteristics. • The combination of mechanochemical milling, hydrogenation, and Mg–Al interface formation lowers the desorption activation energy from 161 ± 2 to 109 ± 1 kJ/mol. • A developed network of vacancies, dislocations, and increased microstrains is identified as the key microstructural feature enabling low-temperature hydrogen desorption. • Positron annihilation spectrometry (PAS) is applied to characterize defect structure evolution, connecting material processing to desorption performance.
Abstract
The current study presents a composite material based on magnesium hydride with the addition of aluminum, obtained by the method of electrical explosion of wires (EEW). The study demonstrated that the material has improved hydrogen interaction characteristics, which is associated with its core–shell structure, defect formation during milling, and the hydrogenation process. The combination of these factors contributes to a decrease in the activation energy of desorption from (161 ± 2) to (109 ± 1) kJ/mol, and consequently, to a reduction in operating temperatures. The data obtained are correlate with a model in which mechanochemical treatment and the formation of Mg–Al interfaces induce a developed network of vacancies, dislocations, and increased microstrains. Based on all of the above, a corresponding mechanism for low-temperature hydrogen desorption from the composite was described.
1. Introduction
The study of physical and chemical processes related to hydrogen storage materials is an integral part of addressing current issues in the field of hydrogen energy and many other areas of industry and science. Establishing patterns and comprehensively describing the mechanisms of hydrogen interaction with such materials is necessary from both a fundamental and applied perspective. The combination of solutions to these aspects and the uniqueness of approaches to the development of hydrogen storage materials with improved properties will be an important step towards the availability of technologies for the storage and transportation of hydrogen as an energy source [1–7].
One of the main factors affecting the interaction of hydrogen with materials is the state of their surface. Surface defects (dislocations, vacancies in surface layers, grain boundaries, steps, and fractures) serve as nucleation sites for the hydride phase of the material, i.e., they increase its reaction capacity with regard to hydrogen. At the same time, it should be noted that the accumulation of hydrogen induces new defects in the bulk of the material, which in turn provokes an increase in internal microstrains. In addition, hydrogen can accumulate in micro fractures, pores, vacancies, and their complexes, dislocations, etc. Each of these defects serves as a sort of hydrogen localization site.
The processes of hydrogen penetration and accumulation in materials cause the accumulation of hydrogen defects and contribute to phase transitions from metal to its hydride. All this leads to an increase in internal strains in the crystal lattice, fracturing, and further degradation [8]. A certain number of hydride-forming metals are used as materials for the extraction, purification, compression, and storage of hydrogen. Researchers around the world are focused on improving the interaction characteristics of materials with hydrogen by adding nanoscale catalysts. These contribute to the improvement of characteristics such as cyclic stability, hydrogen release temperature, process reversibility, sorption/desorption kinetics, etc. [9–17]. The study of these mechanisms in connection with improving the properties of hydrogen storage materials is a relevant area of science for the development of new metal hydride composites for use in hydrogen energy [18–40].
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Alan Kenzhiyev, Viktor N. Kudiiarov, Roman S. Laptev, Roman R. Elman, Andrei V. Mostovshchikov (2025). Enhancing hydrogen desorption in magnesium hydride via nanosized aluminum catalysts synthesized by electrical explosion of wires: Part 2 – The role of formed defect structure. Journal of Mineral Metallurgy and Materials Science. https://doi.org/10.1007/s12613-025-3278-4
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Frequently Asked Questions
What is the main result of this paper?
The study shows that a magnesium hydride composite with nanosized aluminum synthesized by electrical explosion of wires lowers the hydrogen desorption activation energy from 161 ± 2 to 109 ± 1 kJ/mol, enabling lower operating temperatures for hydrogen release.
How was the MgH2–Al composite synthesized?
The composite was produced using the electrical explosion of wires (EEW) method, followed by mechanochemical milling and hydrogenation, which together create a core–shell structure and a rich defect network.
What role do defects play in improving hydrogen desorption?
Defects such as vacancies, dislocations, and microstrains, formed during milling and at Mg–Al interfaces, act as pathways and nucleation sites that facilitate hydrogen diffusion and lower the energy barrier for desorption.
Why is positron annihilation spectrometry (PAS) used in this research?
PAS is used to characterize the type, concentration, and evolution of defects in the material during hydrogen sorption and desorption, allowing a direct correlation between the defect structure and the improved hydrogen storage performance.
What is the significance of this work for hydrogen storage applications?
It provides a scalable synthesis route and a mechanistic understanding of how engineered defect structures and Al catalysts can reduce the operating temperature for hydrogen desorption in magnesium hydride, advancing practical hydrogen storage technologies.
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