Key Takeaways & Executive Findings
- •• A novel tubular g-C3N4@NiFe-LDH nanocomposite was synthesized via solvothermal and pyrolysis methods, exhibiting a well-defined tubular morphology (~3 μm length, ~200 nm diameter) for enhanced dispersion and interfacial contact. • Doping LiAlH4 with 7wt% g-C3N4@NiFe-LDH dramatically improves dehydrogenation kinetics: the onset temperature is lowered to 79.2°C, releasing 6.8wt% hydrogen in two steps. • Kissinger analysis shows that the apparent activation energies for the two dehydrogenation steps are reduced by 43.0% and 54.8%, respectively, indicating significantly enhanced kinetics. • The synergistic effect between the g-C3N4 support and NiFe-LDH, along with potential in-situ formation of active interfacial species, is proposed as the mechanism for the catalytic enhancement.
Abstract
LiAlH4 is hindered for practical hydrogen storage by its high decomposition temperatures, slow kinetics, and poor reversibility. To address the kinetic issues, this study introduces a tubular g-C3N4-supported NiFe-layered double hydroxide (g-C3N4@NiFe-LDH) nanocomposite as a catalytic dopant for LiAlH4. The composite, synthesized via solvothermal and pyrolysis methods, features a well-defined tubular morphology (~3 μm in length, ~200 nm in diameter), which facilitates its homogeneous dispersion and intimate interfacial contact with LiAlH4 during ball milling. Doping with 7wt% of this catalyst dramatically enhances the dehydrogenation kinetics of LiAlH4. The onset dehydrogenation temperature is lowered to 79.2°C, and 6.8wt% of hydrogen is released in two steps. Kissinger analysis reveals that the apparent activation energies for these steps are reduced by 43.0% and 54.8%, respectively, demonstrating significantly improved dehydrogenation kinetics. Mechanistic studies suggest that the synergistic effect between the g-C3N4 support and NiFe-LDH, along with the potential in-situ formation of active interfacial species during dehydrogenation, contributes to this improvement.
1. Introduction
Amid global industrialization and population growth, environmental pollution and increasing oil consumption present pressing challenges [1–2]. Hydrogen energy has emerged as a promising clean alternative due to its high energy density, abundance, and eco-friendliness [3–5]. Among candidate materials, lithium aluminum hydride (LiAlH4) exhibits a high theoretical hydrogen capacity (10.5wt%) and a relatively low desorption temperature [6–7]. However, its practical implementation is limited by slow hydrogen release kinetics and poor cycling stability. To overcome these drawbacks, strategies such as catalytic doping, nanosizing, and composite destabilization with other materials are being actively pursued [8–9].
The findings revealed that only TiCl3 successfully facilitated the hydrogenation of LiH and Al to form LiAlH4 [10–11]. Additionally, TiCl3-doped LiAlH4 produced by hydrogenation began releasing hydrogen at 80°C and maintained a hydrogen content of 6.4wt% after three cycles. LiAlH4 decomposes completely through the following three-step reactions, as shown in Eqs. (1)–(3) [12]. Since the third step occurs at a high temperature of 370°C, which is too high for fuel cell applications, most research has focused on the first two reactions: 3LiAlH4 →Li3AlH6 +2Al + 3H2 ↑ (187−218°C, 5.3wt%) (1); Li3AlH6 →3LiH+Al + 3/2H2 ↑ (228−282°C, 2.6wt%) (2); LiH →Li+1/2H2 ↑ (370−483°C, 2.6wt%) (3).
Although LiAlH4 offers several advantages, its hydrogen desorption kinetics and reversibility remain insufficient for practical applications. To improve the hydrogen storage performance of LiAlH4, several strategies have been explored, including nanostructuring, catalytic doping, and forming composites with other hydrides. Among these approaches, ball milling is widely adopted as a practical method for creating nanostructures. This mechanical process significantly reduces the particle size, enhances the surface area, and generates a high density of structural defects both on the surface and within the material. These changes collectively contribute to improved kinetics and more efficient hydrogen desorption. Wei et al. [13] investigated the thermal stability of both pure and ball-milled LiAlH4. Their findings revealed that ball milling significantly lowers the two-step hydrogen desorption temperatures of LiAlH4. This improvement is primarily due to the reduced particle size, which shortens the hydrogen diffusion path and decreases the thermodynamic properties, thereby lowering the hydrogen desorption temperature and activation energy. Additionally, during ball milling, the mechanical impact of the milling balls on LiAlH4 particles generates localized high temperatures and pressures, causing partial decomposition of LiAlH4 into Li3AlH6 and Al phases. Compared to other modification methods, introducing nanodopants is the most effective and commonly used approach [14]. By combining nanodopants with LiAlH4 through ball milling, both
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Riguang Cheng, Zhaoyu Liu, Hengxin Zhang, Pantrangi Manasa, Hongge Pan, Fen Xu, Lixian Sun, Federico Rosei, and Yan Wang (2025). Pyrolytic/solvothermal synthesis of tubular g-C3N4@NiFe-layered double hydroxide for catalytic enhancement of hydrogen storage in LiAlH4. Journal of Mineral Metallurgy and Materials Science. https://doi.org/10.1007/s12613-026-3400-2
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Frequently Asked Questions
What is the main problem with LiAlH4 for hydrogen storage?
LiAlH4 is hindered by high decomposition temperatures, slow kinetics, and poor reversibility, which limit its practical application despite its high theoretical hydrogen capacity of 10.5wt%.
How does the g-C3N4@NiFe-LDH nanocomposite improve the dehydrogenation of LiAlH4?
Doping LiAlH4 with 7wt% of the tubular g-C3N4@NiFe-LDH nanocomposite lowers the onset dehydrogenation temperature to 79.2°C and releases 6.8wt% hydrogen in two steps, significantly enhancing the kinetics.
What synthesis method was used to prepare the g-C3N4@NiFe-LDH nanocomposite?
The nanocomposite was synthesized via solvothermal and pyrolysis methods, resulting in a well-defined tubular morphology about 3 μm in length and 200 nm in diameter.
What are the key findings from Kissinger analysis in this study?
Kissinger analysis revealed that the apparent activation energies for the two dehydrogenation steps of LiAlH4 are reduced by 43.0% and 54.8%, respectively, confirming significantly improved dehydrogenation kinetics.
What is the proposed catalytic mechanism for the enhanced hydrogen storage?
The enhancement is attributed to the synergistic effect between the g-C3N4 support and NiFe-LDH, along with the potential in-situ formation of active interfacial species during dehydrogenation.
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