Vanadium oxide nanoparticles supported on cubic carbon nanoboxes as highly active catalyst precursors for hydrogen storage in MgH2
Vanadium oxide nanoparticles supported on cubic carbon nanoboxes as highly active catalyst precursors for hydrogen storage in MgH2
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立方碳纳米盒负载的氧化钒纳米颗粒作为用于 MgH2 储氢的高活性催化剂前体
DOI：
10.1039/c8ta05437a
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发表时间：
2018
影响因子：
11.9
通讯作者：
Liu Yongfeng
中科院分区：
文献类型：
--
作者：
Wang Zeyi;Ren Zhuanghe;Jian Ni;Gao Mingxia;Hu Jianjiang;Du Fang;Pan Hongge;Liu Yongfeng
氢化镁（MgH2）作为一种高容量储氢材料引起了人们的广泛关注。但其热稳定性高、动力学慢，限制了其实际应用。本文以MIL-47(V)为前驱体，成功合成了立方碳纳米盒（nano-V2O3@C）上负载的氧化钒纳米颗粒，并证明了nano-V2O3@C复合材料对MgH2储氢反应的优异催化作用。MgH2-9 wt% nano-V2O3@C样品在215°C时开始释放氢，比不添加添加剂的MgH2低60°C。在275°C时，大约6.4 wt%的氢在20分钟内从MgH2-9 wt% V2O3@C样品中释放出来。脱氢后的样品即使在50 bar氢气压力下的室温下也能吸收氢气，在150℃下700 s内完成加氢。XRD和XPS检测发现球磨后金属V的存在，并且在随后的加热脱氢/加氢过程中金属V的存在几乎保持不变。进一步的从头计算表明，V的存在促进了MgH2单元Mg-H键的断裂，这是显著降低操作温度和改善V催化MgH2动力学的合理原因。
Magnesium hydride (MgH2) has attracted intense interest as a high-capacity hydrogen storage material. However, high thermal stability and slow kinetics limit its practical applications. Herein, vanadium oxide nanoparticles supported on cubic carbon nanoboxes (nano-V2O3@C) are synthesized successfully by using MIL-47(V) as a precursor, and superior catalytic effects derived from the nano-V2O3@C composite towards the hydrogen storage reaction of MgH2 are demonstrated. The MgH2-9 wt% nano-V2O3@C sample starts releasing hydrogen at 215 °C, which is 60 °C lower than that of the additive-free MgH2. At 275 °C, approximately 6.4 wt% of hydrogen is released from the MgH2-9 wt% V2O3@C sample within 20 min. The dehydrogenated sample absorbs hydrogen even at room temperature under 50 bar of hydrogen pressure, and rehydrogenation is complete within 700 s at 150 °C. XRD and XPS measurements identify the existence of metallic V after ball milling, and its presence remains nearly constant in the subsequent dehydrogenation/hydrogenation process upon heating. Further ab initio calculations reveal that the presence of V facilitates the breaking of the Mg–H bond of the MgH2 unit, which is reasonably responsible for the significantly reduced operating temperatures and improved kinetics of the V-catalysed MgH2.