Hydrogenation/dehydrogenation in MgH2-activated carbon composites prepared by ball milling |
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Authors: | Yi Jia Yanan Guo Jin Zou Xiangdong Yao |
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Affiliation: | 1. ARC Centre of Excellence for Functional Nanomaterials, University of Queensland, St Lucia, Brisbane QLD 4072, Australia;2. School of Mechanical and Mining Engineering, University of Queensland, St Lucia, Brisbane QLD 4072, Australia;3. Centre for Microscopy & Microanalysis (CMM), University of Queensland, St Lucia, Brisbane QLD 4072, Australia;4. Queensland Micro- and Nanotechnology Centre (QMNC), Griffith University, Nathan, Brisbane, QLD 4111, Australia |
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Abstract: | A systematic investigation was performed on the hydrogen storage behaviors of ball-milled MgH2-activated carbon (AC) composites. Differential Scanning Calorimetry (DSC) measurement on the desorption temperature was carried out and indicated that the onset and peak temperatures both decreased with increasing AC adding amount, for example, the desorption peak temperature shifted from 349 °C for 1 wt% AC to 316 °C for 20 wt% AC. Furthermore, it is noted that the hydrogen absorption capacity and hydriding kinetics of the composites were also dependent on the adding amount of AC, and the optimum condition could be achieved by mechanical milling of MgH2 with 5 wt% AC. The Mg-5wt%AC composite can absorb about 6.5 wt% hydrogen within 7 min at 300 °C and 6.7 wt% within 2 h at 200 °C, respectively. It is also demonstrated that MgH2-5wt% AC exhibited good hydrogen desorption property that could release 6.5 wt% at 330 °C within 30 min. X-ray diffraction patterns (XRD) and transmission electron microscopy (TEM) observations revealed that the grain size of the synthesized composites decreased with increasing AC amount. This may contribute to the improvement of hydrogen storage in MgH2-AC composites. |
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Keywords: | Hydrogen storage MgH2-activated carbon (AC) composites Hydrogenation/dehydrogenation Microstructure Mechanical milling |
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