| Budget Amount *help |
¥3,620,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥420,000)
Fiscal Year 2007: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
Fiscal Year 2006: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Research Abstract |
Hydrogen capacities of single-walled carbon nanotubes (SWCNTs), which were synthesized by arc-discharge between graphite rods having Ni-Y catalysts and were sono-chemically treated in nitric acid to be free of bundle-like structures and free from metallic species contaminated on arc-discharge, were less than 0.1 wt.% at room temperature and 0.1 MPa of hydrogen, that is, essentially zero.
Metal modification was carried out by non-electrolytic plating or by thermal decomposition of organometallic compounds and hydrogen capacities were evaluated by Temperature Programmed Desorption (TPD) after deuterium was formed. High hydrogen capacities were observed when palladium, iron, nickel etc. or combinations of them were distributed on SWCNTs. Howeve4 hydrogen capacities of those SWCNTs which were in situ modified with metals on synthesis (PVD) were larger than the ones modified by the wet methods.
Heats on combustion of SWCNTs modified with iron group elements significantly exceeded those of c
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arbons, which suggested that endothermic bonding was formed between SWCNTs and metals. The rule of reversed stability, which generally holds for metal hydrides, thus gives a prediction that SWCNTs modified with iron group elements were unstable enough to form stable hydrides, and that has been verified by the above-mentioned results. Since hydrogen capacities close to 1 wt% have been obtained for SWCNTs with low specific surface areas of 200 m2/g, practical hydrogen storage materials will be developed by increasing specific surface areas to 2,000 m2/g.
Another in situ modification comprising chemical vapor deposition (CVD) gave promising nanocarbons when Mg-Ni or Mg-Fe powders were present The TPD analysis showed plausible higher hydrogen capacities for CVD samples than for PVD samples. Large scale synthesis is now under progress to evaluate the qualitative capacities by isothermal measurements.
Hydrogen capacities were also imparted to B-C-N compounds with layered structures by similar metal modifications. Less
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