The catalytic effect of single-wall carbon nanotubes on the hydrogen sorption properties of sodium alanates

Abstract

Single-wall carbon nanotubes (SWNTs) were examined as catalysts for improving the hydrogen absorption and desorption properties of Ti/Zr-doped NaAlH4 hydride, proposed as a reversible hydrogen storage material. We studied the hydrogen charge and discharge characteristics and stability of sodium aluminium composites ball milled with carbon additives such as SWNTs, graphite or activated carbon (AX-21). The SWNT–NaAlH4 system was tested at 160 °C for up to 200 cycles, and the sorption kinetics were enhanced by a factor of four. Also, the catalyzed NaAlH4 hydride with graphite and activated carbon additives shows fast absorption and desorption kinetics. Our results indicate that by creating new hydrogen transition sites, the structure of carbon in the composites plays an important role in enhancing the hydrogen absorption and release rates.

Effect of activated alloys on hydrogen discharge kinetics of MgH2 nanocrystals

“…It was believed that carbon would favour a more efficient catalyst particle distribution. Moreover, recent studies have demonstrated that co-milling metal hydrides with carbon improves hydrogen sorption kinetics [10][11][12][13][14][15][16], suggesting that carbon plays a catalytic role. Zr 7 Ni 10 was chosen for the experiment, among the Zr x Ni y catalysts investigated in this work, because this particular composition is easier to activate, thus easier to turn into a fine powdery form.…”

Enhanced hydrogen reaction kinetics of nanostructured Mg-based composites with nanoparticle metal catalysts dispersed on supports

“…As for a supporting material for the deposition of metal nanocatalysts, SWNTs was used because it was reported that SWNTs can act as catalysts to improve the hydrogen absorption and desorption properties of metallic catalyst-doped hydrides [14,15].I tw a s also reported that the nanotube length decreases with increasing ball milling time [16]. In order to prevent the thorough destruction of SWNTs during the high energy milling, a short milling time of 20 min was applied for mixing the milled MgH 2 -BCN composite and the SWNTs-supported Ni/Pd catalysts in this study.…”

Carbon Nanomaterials as Catalysts for Hydrogen Uptake and Release in NaAlH4

“…Several groups have investigated the use of carbon materials as possible catalysts for NaAlH 4 , and samples were almost exclusively ball milled (10)(11)(12)(13)(14). Four of these groups report that carbon materials are catalysts for the dehydrogenation and rehydrogenation of NaAlH 4 (10)(11)(12)(13).…”

“…Four of these groups report that carbon materials are catalysts for the dehydrogenation and rehydrogenation of NaAlH 4 (10)(11)(12)(13).…”