Improvement of thermal stability and reduction of LiBH4/polymer host interaction of nanoconfined LiBH4 for reversible hydrogen storage


Addition of multi-wall carbon nanotube (MWCNT) and NaAlH4 into nanoconfined LiBH4–PcB (poly (methyl methacrylate)–co–butyl methacrylate) for improving thermal stability and reducing LiBH4/PcB interaction is proposed. The greater the amount of gases desorbed due to polymer (PcB) degradation, the less the thermal stability of polymer host. During dehydrogenation of nanoconfined LiBH4–PcB, combination of gases due to PcB degradation is 64.3% with respect to H2 content, while those of nanoconfined samples doped with MWCNT and NaAlH4 are only 9 and 7.9%, respectively. The LiBH4/PcB (i.e., B⋯OCH3) interaction is quantitatively evaluated by FTIR technique. The more the ratio of peak area between υ(B–H) (from LiBH4) and υ(CO) (from PcB), the lower the LiBH4/PcB interaction. It is found that by adding small amount of MWCNT and NaAlH4, this ratio significantly increases up to 78%. This is in agreement with B 1s XPS results, where the relative amount of BxOy (x/y = 3) to LiBH4 decreases after adding MWCNT and NaAlH4 into nanoconfined LiBH4–PcB. It should be remarked that significant improvement of thermal stability and decrease of LiBH4/PcB interaction after adding MWCNT and NaAlH4 into nanoconfined LiBH4–PcB result in considerable amount of hydrogen release and uptake as well as hydrogen reproducibility during cycling. However, the dispersion of MWCNT is still one of the most critical factors to be concerned due to probably its hindrance for hydrogen diffusion.
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