Graphene‐Tailored Thermodynamics and Kinetics to Fabricate Metal Borohydride Nanoparticles with High Purity and Enhanced Reversibility
Graphene‐Tailored Thermodynamics and Kinetics to Fabricate Metal Borohydride Nanoparticles with High Purity and Enhanced Reversibility
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DOI：
10.1002/aenm.201702975
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发表时间：
2018-05
影响因子：
27.8
通讯作者：
Hongyu Zhang;Guanglin Xia;Jian Zhang;Dalin Sun;Zaiping Guo;Xuebin Yu
中科院分区：
文献类型：
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作者：
Hongyu Zhang;Guanglin Xia;Jian Zhang;Dalin Sun;Zaiping Guo;Xuebin Yu
金属硼氢化物由于其优良的储氢性能，被认为是最有前途的储氢材料之一。然而，它们的应用仍然受到操作温度高、动力学缓慢和可逆性差的影响。设计纳米结构是解决这些问题的有效方法，但寻找合适的方法仍然是一个巨大的挑战。在这里，报道了空间受限的固气反应合成石墨烯负载的Mg（BH 4）2纳米颗粒，它作为分散的Mg（BH 4）2纳米颗粒的结构支撑。密度泛函理论计算表明，石墨烯可以削弱MgH 2中的Mg-H键和B2 H6中的B-B键，从而在热力学和动力学上促进Mg（BH 4）2的化学转化，合成高纯度的Mg（BH 4）2。由于颗粒尺寸的显著减小和石墨烯的催化作用两者的协同效应，观察到Mg（BH 4）2纳米颗粒的开始脱氢温度为154 °C，并且可以在低至225 °C的温度下实现完全脱氢，形成MgB 2作为副产物。这一工作提供了一个新的视角，剪裁的热力学和动力学的化学反应朝着有利的合成功能无机材料。
Due to their ultrahigh theoretical capacity, metal borohydrides are considered to be one of the most promising candidate hydrogen storage materials. Their application still suffers, however, from high operating temperature, sluggish kinetics, and poor reversibility. Designing nanostructures is an effective way of addressing these issues, but seeking suitable approaches remains a big challenge. Here, a space‐confined solid‐gas reaction to synthesize Mg(BH4)2 nanoparticles supported on grapheme is reported, which serves as the structural support for the dispersed Mg(BH4)2 nanoparticles. More notably, density functional theory calculations reveal that graphene could weaken both the MgH bonds of MgH2 and BB bonds of B2H6, which could thermodynamically and kinetically facilitate the chemical transformation to synthesize Mg(BH4)2 with high purity. Because of the synergistic effects of both the significant reduction in particle size and the catalytic effect of graphene, an onset dehydrogenation temperature of ≈154 °C is observed for Mg(BH4)2 nanoparticles, and a complete dehydrogenation could be achieved at a temperature as low as 225 °C, with the formation of MgB2 as the by‐product. This work provides a new perspective to tailoring the thermodynamics and kinetics of chemical reactions toward the favorable synthesis of functional inorganic materials.