Hydrogen storage performance of 2LiH + MgB2 doped with hydrothermal-synthesized ZrO2 nanorods

•ZrO2 nanorods were synthesized through a hydrothermal reaction.•ZrO2 nanorods were doped in the 2LiH + MgB2 composite.•Hydrogen storage performance was greatly improved due to the ZrO2 doping.•A good cycle performance was achieved after the ZrO2 nanorod doping.•Nanosized ZrB2 formed in situ accounted for the performance enhancement.

In this study, we synthesized ZrO2 nanorods through a hydrothermal process as a catalyst precursor for the reversible hydrogen storage reaction between 2LiH + MgB2 and 2LiBH4 + MgH2. The 2LiH + MgB2 composites doped with the ZrO2 nanorods demonstrated superior and stable hydriding/dehydriding kinetics upon cycling. The XRD, SEM and HRTEM results revealed that the doped ZrO2 nanorods were transformed into ZrB2 nanoparticles with a size of a few nanometers during the first hydrogenation. The initial nanosize of the ZrO2 catalyst precursor accounted for the formation of extremely fine ZrB2 nanoparticles, which acted as heterogeneous nuclei of MgB2. The present study provides a new route for performance enhancement of complex hydride composites through manipulating the nanostructure of catalysts.