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

Abstract

Sodium alanate (NaAlH ) has attracted intense interest as a prototypical high-density hydrogen-storage material. However, poor reversibility and slow kinetics limit its practical applications. Herein, a nanocrystalline ZrO @C catalyst was synthesized by using Uio-66(Zr) as a precursor and furfuryl alcohol (FA) as a carbon source. The as-synthesized ZrO @C exhibits good catalytic activity for the dehydrogenation and hydrogenation of NaAlH . The NaAlH -7 wt % ZrO @C sample released hydrogen starting from 126 °C and reabsorbed it starting from 54 °C, and these temperatures are lower by 71 and 36 °C, respectively, relative to pristine NaAlH . At 160 °C, approximately 5.0 wt % of hydrogen was released from the NaAlH -7 wt % ZrO @C sample within 250 min, and the dehydrogenation product reabsorbed 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.

Amorphous-Carbon-Supported Ultrasmall TiB2 Nanoparticles With High Catalytic Activity for Reversible Hydrogen Storage in NaAlH4

“…These dehydrogenation kinetics outperform those of other TiB 2 -doped NaAlH 4 , which released only 2.79 wt% under the same conditions (Li et al, 2012b). Using the Kissinger's method (Kissinger, 1957), the apparent activation energies (E a ) were determined to be ∼82.8 and 71.8 kJ/mol for the first and second dehydrogenation of the 7 wt%-nano-TiB 2 @C-containing sample, respectively (Figure 3E), which are ∼ 40% lower than those of pristine NaAlH 4 (Zhang et al, 2016) and is responsible for the remarkably reduced dehydrogenation temperatures.…”

Development of Catalyst‐Enhanced Sodium Alanate as an Advanced Hydrogen‐Storage Material for Mobile Applications

“…At 140 °C, approximately 4.2 wt % hydrogen is released within 10 min, and this represents the fastest dehydrogenation kinetics reported thus far for NaAlH 4 system. Moreover, nanocrystalline CeO 2 @C and ZrO 2 @C have also been successfully synthesized and have been shown to exhibit superior catalytic effects on NaAlH 4 . The prepared 7 wt % CeO 2 @C‐containing sample releases approximately 4.7 wt % hydrogen at 95–190 °C in the non‐isothermal mode, and the dehydrogenated sample is completely hydrogenated within 35 min at 100 °C and 100 bar H 2 …”

“…Moreover, nanocrystalline CeO 2 @C and ZrO 2 @C have also been successfully synthesized and have been shown to exhibit superiorc atalytice ffects on NaAlH 4 . [81,87] Thep repared 7wt% CeO 2 @C-containing sample releases approximately 4.7 wt %h ydrogen at 95-190 8Ci nt he non-isothermal mode,a nd the dehydrogenated samplei sc ompletely hydrogenated within 35 min at 100 8Cand 100 bar H 2 . [81]…”

Controllable synthesis of 2D TiH2 nanoflakes with superior catalytic activity for low-temperature hydrogen cycling of NaAlH4

“…9a and b, the activation energies were calculated to be 84 and 80 kJ mol -1 for the first and second steps of dehydrogenation of the activated (ie., after 1 st rehydrogenation) sample, respectively, which are 6-8% lower than those of the as-milled sample. Compared with pristine NaAlH4 [46], the numbers are reduced by approximately 35%, illustrating the superior catalytic activity of TiH2 nanoflakes.…”