Revisiting the Hydrogen Storage Behavior of the Na-O-H System

Materials

Jianfeng Mao¹  Qinfen Gu²  Duncan H. Gregory¹ 

[1] WestCHEM, School of Chemistry, Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, UK; E-Mail:;Australian Synchrotron, Clayton, Victoria 3168, Australia; E-Mail:

关键词: hydrogen storage;    sodium oxide;    sodium hydride;    sodium hydroxide;    in-situ synchrotron powder diffraction;   

DOI  :  10.3390/ma8052191

来源: mdpi

【 摘 要 】

Solid-state reactions between sodium hydride and sodium hydroxide are unusual among hydride-hydroxide systems since hydrogen can be stored reversibly. In order to understand the relationship between hydrogen uptake/release properties and phase/structure evolution, the dehydrogenation and hydrogenation behavior of the Na-O-H system has been investigated in detail both ex- and in-situ. Simultaneous thermogravimetric-differential thermal analysis coupled to mass spectrometry (TG-DTA-MS) experiments of NaH-NaOH composites reveal two principal features: Firstly, an H₂ desorption event occurring between 240 and 380 °C and secondly an additional endothermic process at around 170 °C with no associated weight change. In-situ high-resolution synchrotron powder X-ray diffraction showed that NaOH appears to form a solid solution with NaH yielding a new cubic complex hydride phase below 200 °C. The Na-H-OH phase persists up to the maximum temperature of the in-situ diffraction experiment shortly before dehydrogenation occurs. The present work suggests that not only is the inter-phase synergic interaction of protic hydrogen (in NaOH) and hydridic hydrogen (in NaH) important in the dehydrogenation mechanism, but that also an intra-phase H^δ+… H^δ– interaction may be a crucial step in the desorption process.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.