Synthesis of nanoscale CeAl₄ and its high catalytic efficiency for hydrogen storage of sodium alanate

Nanoscale CeAl₄ was directly synthesized by the thermal reaction between CeH₂ and nano-aluminum at 300 °C. Then nano CeAl₄-doped sodium alanate (NaAlH₄) was synthesized by ball milling NaH/Al with 0.04CeAl₄ under hydrogen atmosphere at room temperature, and the catalytic efficiency of nanoscale CeAl₄ for hydrogen storage of NaAlH₄ was systematically investigated. It is shown that CeAl₄ can effectively improve the dehydrogenation properties of sodium alanate system. The 0.04CeAl₄-doped NaAlH₄ system starts to release hydrogen below 80 °C, completes dehydrogenation within 10 min at 170 °C, and exhibits good cycling de/hydrogenation kinetics at relatively lower temperature (100–140 °C). Apparent activation energy of the dehydrogenation of NaAlH₄ can be effectively reduced by addition of CeAl₄, resulting in the decrease in desorption temperatures. Moreover, by analyzing the reaction kinetics of nano CeAl₄-doped NaAlH₄ sample, both of the decomposition steps are conformed to a two-dimensional phase-boundary growth mechanism. The mechanistic investigations gained here can help to understand the de-/rehydrogenation behaviors of catalyzed complex metal hydride systems.

Nanoscale CeAl₄ was successfully synthesized and doped into NaAlH₄ system ball milling NaH/Al + 0.04CeAl₄. The addition of CeAl₄ can effectively improve the dehydrogenation properties of NaAIH4, which starts to release hydrogen below 80 °C, completes dehydrogenation within 10 min at 170 °C, and exhibits good cycling de/hydrogenation kinetics at relatively lower temperature.