Abstract:The as-prepared Ti-Zr hydride powder is used as dopant to improve hydrogen storage properties of NaAlH₄ upon mechanical milling under argon atmosphere. The as-milled sample is investigated by X-ray diffraction(XRD), scanning electron microscopy(SEM) and Sievert’s technology test. It is observed that Ti-Zr hydride doped NaAlH₄ discharges 2.7% and 4.0% (mass fraction) of hydrogen in 40 min and 11 h at 160 ℃, respectively, and keeps its reversible dehydrogenation capacity at 4.0% (mass fraction) after 10 hydrogenation/dehydrogenation cycles. These results show the Ti-Zr hydride doped NaAlH₄ has good reversible hydrogen storage capacity and kinetics. XRD and SEM investigations also show that the doped Ti-Zr hydride uniformly distributes in NaAlH₄ substrate and keeps stable during the hydrogenation/dehydrogenation cycle, indicating that Ti-Zr hydride plays the main surface-catalytic role on improving reversible hydrogen storage properties of NaAlH₄.

Key words: hydrogen storage materials; sodium alanates; Ti-Zr hydride dopant