Mechanistic understanding of the superior catalytic effect of Al65Cu20Fe15 quasicrystal on de/re-hydrogenation of NaAlH4

Abstract

The complex hydride NaAlH4 remains the archetype hydrogen storage system. In this paper, we have explored the catalytic action of Al65Cu20Fe15 quasicrystal (QC) on the de/re-hydrogenation study of NaAlH4. The leached ball-milled Al65Cu20Fe15 (LBMACF) catalyzed NaAlH4 sample has shown a lower hydrogen desorption temperature (140 °C) than other catalyzed and uncatalyzed NaAlH4 samples. NaAlH4-LBMACF rapidly absorbed ∼3.20 wt% of hydrogen within 1 min and absorbed maximum capacity (∼4.68 wt%) in 15 min, while NaAlH4-LACF, NaAlH4-BMACF, NaAlH4-ACF, and pristine NaAlH4 absorbed only 0.50 wt%, 1.38 wt%, 1.10 wt%, and 0.70 wt% in 1 min at 130 °C under 100 atm hydrogen pressure. NaAlH4-LBMACF has desorbed ∼4.22 wt% of hydrogen within 15 min, while the same amount of hydrogen desorbed by NaAlH4-LACF takes 45 min at 130 °C under 1 atm hydrogen pressure. NaAlH4-LBMACF shows reversibility up to 25 cycles with minimum degradation of hydrogen storage capacity of ∼0.06 wt% during de/re-hydrogenation. The catalytic mechanism and catalytic effect of Al–Cu–Fe on the NaAlH4 have been discussed using structural, microstructural analysis, in-situ nuclear magnetic resonance (NMR) spectroscopy, in-situ Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS).