Hydriding/dehydriding properties of MgH2/5 wt.% Ni coated CNFs composite
Hydriding/dehydriding properties of MgH2/5 wt.% Ni coated CNFs composite
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DOI：
10.1016/j.ijhydene.2009.10.079
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发表时间：
2010
影响因子：
7.2
通讯作者：
Chengzhang Wu;X. Yao;H. Zhang
中科院分区：
文献类型：
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作者：
Chengzhang Wu;X. Yao;H. Zhang
本文报道了采用化学镀法制备的镍包覆碳纳米纤维(NiCNF)对镁(Mg)的吸放氢催化性能。结果表明，球磨法制备的∼/5wt.%NiCNF纳米复合材料在低温下吸氢速度非常快，即使在423K的温度下，也能在5min内吸氢6.0wt.%，在10min内吸氢∼5.0wt.%。更重要的是，添加NiCNF也显著改善了氢气的脱附。DSC测试表明，脱附峰温降低了50K，脱附起始温度降低了123K。在573K下，复合材料在20min内可快速脱附氢气，脱附率为5.5wt.%。结果表明，镁镍的新相以及镍和碳的纳米弥散分布对这一显著的改善起到了重要作用。Johnson-Mehl-Avrami(JMA)分析表明，氢的扩散是氢吸附/脱附的限速步骤。
In this paper, we reported that the prepared nickel coated carbon nanofibers (NiCNFs) by electroless plating method exhibited superior catalytic effect on hydrogen absorption/desorption of magnesium (Mg). It is demonstrated that the nanocomposites of MgH2/5wt.% NiCNFs prepared by ball milling could absorb hydrogen very fast at low temperatures, e.g. absorb ∼6.0wt.% hydrogen in 5 min at 473K and ∼5.0 wt.% hydrogen in 10 min even at a temperature as low as 423K. More importantly, the desorption of hydrogen was also significantly improved with additives of NiCNFs. Diffraction scanning calorimetry (DSC) measurement indicated that the peak desorption temperature decreased 50K and the on-set temperature for desorption decreased 123K. The composites also desorbed hydrogen fast, e.g. desorb 5.5wt.% hydrogen within 20min at 573K. It is suggested that the new phase of Mg2Ni, and the nano-sized dispersed distribution of Ni and carbon contributed to this significant improvement. Johnson–Mehl–Avrami (JMA) analysis illustrated that hydrogen diffusion is the rate-limiting step for hydrogen absorption/desorption.