Preparation and Catalytic Activity of a Novel Nanocrystalline ZrO2@C Composite for Hydrogen Storage in NaAlH4

Sodium alanate (NaAlH4) has attracted intense interest as a prototypical high-density hydrogen storage material. However, poor reversibility and slow kinetics limit its practical applications. In this work, a nanocrystalline ZrO2@C catalyst is synthesized using Uio-66(Zr) as a precursor and furfuryl alcohol (FA) as a carbon source. The as-synthesized ZrO2@C exhibits good catalytic activity for dehydrogenation and hydrogenation of NaAlH4. The NaAlH4-7 wt% ZrO2@C sample releases hydrogen starting from 126 °C and re-absorbs starting from 54 °C, and these temperatures are reduced by 71 °C and 36 °C, respectively, relative to those of pristine NaAlH4. At 160 °C, approximately 5.0 wt% of hydrogen is released from the NaAlH4-7 wt% ZrO2@C sample within 250 min, and the dehydrogenation product re-absorbs approximately 4.9 wt% within 35 min at 140 °C and 100 bar of hydrogen. The catalytic function of the Zr-based active species is believed to contribute to the significantly reduced operating temperatures and enhanced kinetics.