Improving hydrogen sorption performances of MgH2 through nanoconfinement in a mesoporous CoS nano-boxes scaffold

Recent advances in Mg-based hydrogen storage materials

“…Mg 基材料纳米化是提高 MgH 2 /Mg 体系吸放氢热/动力学性能的有效方法 [70] 。 早在 1980 年代， Bogdabovic 等人 [71] 通过在有机溶液中对二茂镁进行氢化来制备尺寸为 50-500 nm 的 MgH 2 纳米颗粒， 储氢性能大幅提升。 Wagemans 等人 [72] 计算了 MgH 2 尺寸对放氢焓变的影响。 结果表明， 块体 MgH 2 和 MgH 2 纳米粒子 (~0.9 nm) 的放氢焓变分别为 75 和 63 kJ mol -1 H 2 ，纳米 MgH 2 分解温度可以降低到约 200°C 。 近年来，国内外研究者们尝试用不同纳米化技术来制备纳米镁基材料，包括高能球磨法 [56] 、化学还原 法 [73~77] 、氢化法 [78~81] 、气相沉积法 [82,83] 和熔融法等，取得了卓有成效的研究成果。高能球磨法已被广泛用 于纳米镁基材料的制备，但是不能精准控制材料粒度分布在所需的狭窄范围内 [56] 。此外，高能球磨法易引 入杂质，并且易引起材料的团聚和长大，使得循环稳定性减低。因此，最近的研究工作集中于制备可控、 尺寸均匀的纳米 Mg 基材料的化学还原法、氢化法和气相沉积法。 [75,76] [79] 、MOF [80,81] 等新型材料中，显著改善了镁基材料的储氢性 能。Xia 等人 [79] 在温和的反应条件下(200 °C 和 3.5 MPa H 2 )通过氢化法合成石墨烯负载 MgH 2 和 Ni 纳米 颗粒。MgH 2 -Ni-石墨烯复合材料的吸/放氢性能和微观结构如图 4a-d 所示。该复合材料在 100 个循环后的储 氢量仍为 5.35wt%。TEM 结果表明，制得的 MgH 2 纳米粒子尺寸较小(仅 2-5n m)且分散性较高(图 4c) ， 因此具有优异的热/动力学性能。Ma 等人 [80,81] [79] ； (e)HAADF 图、 (f)HRTEM 图、 (g)PCI 曲线和(h)van's Hoff 方程拟合曲线 [80] . Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.…”

Enhanced Hydrogen Storage Performance of MgH2 by the Catalysis of a Novel Intersected Y2O3/NiO Hybrid

“…Common methods to improve the hydrogen storage performance of MgH 2 include alloying [9][10][11][12][13][14][15][16][17][18], nanoconfinement [19,20], nano-crystallization [21][22][23][24][25][26], and catalyst doping [27][28][29][30][31][32][33][34][35]. Alloying of Mg by combining with other metal elements, such as Al, Ni, and Ge, can produce less stable Mg-based hydrides.…”

“…One typical example is Mg 2 NiH 4 , which has a low theoretical capacity of only 3.6 wt%, though its dehydrogenation temperature is decreased to 255 • C at 1 bar equilibrium H 2 pressure [34]. Nano-crystallization is effective in modifying the thermodynamics and kinetics of MgH 2 , especially the latter [19][20][21][22][23][24][25][26]. For thermodynamic modification, theoretical calculations suggest that when the grain size of MgH 2 is reduced to 0.9 nm, the decomposition enthalpy is only 63 kJ mol −1 H 2 , corresponding to a theoretical desorption temperature of only 200 • C [36].…”

“…Progress has been obtained on the improvement of the hydrogen storage performance of MgH 2 ; however, the synthesis of the highly active catalysts seems complicated, such as with the Fe 0.64 Ni 0.36 @C catalyst, where several synthesis steps and almost 3 days are needed for one period [27], and the catalyst of MXene-Ti 3 C 2 needs almost one week for one synthesis period [28]. Some of the other catalysts shows moderate effects on the improvement of MgH 2 [14,19,32], though they can improve the hydrogen storage properties of MgH 2 to some extent. Therefore, developing highly effective catalysts with facile synthesis methods is still highly desired.…”

“…In the present work, we design and synthesize a novel structural intersected Y 2 O 3 /NiO hybrid by a facile spray sintering method, which shows highly effective catalysis on MgH 2 . Compared with some chemical synthesis methods, such as the hydrothermal method [19], which generally has low productivity, the present synthesis method has high productivity, which has the potential for large-scale production. The hybrid shows a spherical hollow structure.…”