Peng Dandan, Ding Zhenmin, Fu Yaokun, Wang Yu, Bi Jia, Li Yuan, Han Shumin
State Key Laboratory of Metastable Materials Science and Technology, Yanshan University Qinhuangdao 066004 P. R. China.
School of Environmental and Chemical Engineering, Yanshan University Qinhuangdao 066004 P. R. China
RSC Adv. 2018 Aug 13;8(50):28787-28796. doi: 10.1039/c8ra05464a. eCollection 2018 Aug 7.
Magnesium hydride is regarded as one of the most ideal candidates for hydrogen storage, but its relatively high operating temperatures and slow kinetics always hinder its commercial applications. Herein, we first fabricated hard-carbon-sphere-wrapped Ni (Ni/HCS) a mild chemical method; subsequently, the as-prepared additive was introduced to fabricate an Mg-Ni/HCS composite by using hydriding combustion synthesis. Hard carbon spheres (HCS) effectively inhibited the agglomeration of hydride particles during hydrogen storage cycling; they could also provide active sites to promote the nucleation of Mg-based hydrides. During the hydriding combustion synthesis procedure, -formed MgNiH could induce the absorption of MgH, thus triggering its hydrogen properties. Remarkable enhancement in hydrogen absorption properties of the composite was found. The composite absorbed 6.0 wt% H within 5 min at 275 °C; moreover, even at 75 °C, it could still absorb 3.5 wt% H. Furthermore, it delivered a high reversible hydrogen absorption capacity of 6.2 wt% and excellent rate capability at 350 °C. It was also demonstrated that the composite could release 6.2 wt% H at 350 °C within 5 min. A rather low activation energy value (65.9 kJ mol) for the dehydrogenation of MgH was calculated as compared to that for commercial MgH (133.5 kJ mol).
氢化镁被认为是最理想的储氢材料之一，但其相对较高的工作温度和缓慢的动力学过程一直阻碍着它的商业应用。在此，我们首先通过温和的化学方法制备了硬碳球包裹的镍（Ni/HCS）；随后，将所制备的添加剂引入，采用氢化燃烧合成法制备了Mg-Ni/HCS复合材料。硬碳球（HCS）在储氢循环过程中有效抑制了氢化物颗粒的团聚；它们还能提供活性位点以促进镁基氢化物的成核。在氢化燃烧合成过程中，生成的MgNiH可诱导MgH的吸收，从而引发其储氢性能。发现该复合材料的吸氢性能有显著提高。该复合材料在275℃下5分钟内吸收了6.0 wt%的氢；此外，即使在75℃下，它仍能吸收3.5 wt%的氢。此外，它在350℃下具有6.2 wt%的高可逆吸氢容量和优异的速率性能。还证明了该复合材料在350℃下5分钟内可释放6.2 wt%的氢。与商用MgH（133.5 kJ/mol）相比，计算得出MgH脱氢的活化能值相当低（65.9 kJ/mol）。
