LAUSR

Abstract Nanoconfinement of NaAlH4 inside a nanoporous carbon material and its effect on the reversible hydrogen storage has been studied. NaAlH4 has been deposited into/onto a highly microporous carbon material by solution impregnation method. The structure of the deposited NaAlH4 and H2 release from NaAlH4 after deposition and after 10 dehydrogenation/hydrogenation cycles has been investigated. Materials with smaller NaAlH4 particles and a higher ratio of amorphous NaAlH4 phase start releasing hydrogen at ambient temperatures (>23 °C). Hydrogen release takes place from nanostructured NaAlH4 with a more even rate over a larger temperature interval. During repetitive cycling, the crystalline NaAlH4 had been converted into amorphous nanoconfined phase or irreversibly decomposed into bulk phases, crystalline Al and Na3AlH6, which have been detected by X-ray diffraction method. Hydrogen release from nanoconfined amorphous NaAlH4 started already at ambient temperatures. Improved reversibility of H2 storage has been demonstrated. The data for nanoconfined material has been compared to bulk NaAlH4.