Hydrogen Storage Properties of Space-Confined NaAlH₄ Nanoparticles in Ordered Mesoporous Silica

Abstract

A method that is used by space-confining NaAlH4 into the as-synthesized ordered mesoporous silica (OMS) is presented in the present work. NaAlH4 in the pores of OMS is obtained by impregnation and drying techniques. It has been found that the space-confined NaAlH4 in the pores of OMS shows the lower temperature and faster kinetics for dehydrogenation than that of the pristine NaAlH4. Moreover, in the absence of a catalyst, the rehydrogenation in a dehydrogenated NaAlH4 system with nanoscale particles and phases can be achieved even with the temperatures of 125−150 °C and the hydrogen pressures of 3.5−5.5 MPa. The physical limitation of the NaAlH4 particles, as well as the resulting Al and NaH phases, to be nanoscale in size by the pores of OMS is believed to be responsible for these.