Hydrogen generation from the ball milled composites of sodium and lithium borohydride (NaBH 4 /LiBH 4 ) and magnesium hydroxide (Mg(OH) 2 ) without and with the nanometric nickel (Ni) additive

Preparation of graphene-supported highly dispersed nickel nanoparticles for the improved generation of hydrogen from ball-milled LiBH4

“…60.5 m 2 g −1 ). 25,26 In addition, the Ni/G catalysts prepared were porous, 32 and the pore size distribution plot showed that the pores had a narrow micro-mesoporous size distribution centred at ca. 3.8 nm (see inset in Fig.…”

“…Among these catalysts, nanometerscale Ni additives are typical catalysts for LiBH 4 by virtue of their high catalytic effect, physical hydridising properties, low cost and benign environmental effect. 5,[23][24][25][26] For instance, the onset hydrogen release temperature can be decreased to around 300 °C, and about 12.1 wt.% H 2 per LiBH 4 can be introduced at 10 MPa in the first cycle at 600 °C for 30 h by ball milling LiBH 4 and Ni at a molar ratio of 2 : 1. 23 However, a wide range of nickel catalysts are available commercially, and tend to be partially oxidized and agglomerated before use, as confirmed by X-ray diffraction (XRD) and photoemission spectroscopy (XPS), and morphology analysis.…”

“…The addition of oxidised nickel nanoparticles leads to the partial oxidation of LiBH 4 and the appearance of irreversible products during the rehydrogenation cycle, and thus some deterioration of hydrogen storage properties and cycle life. 26 In addition, the particle size of these commercial nickel additives can be as high as 41 μm, 23 and their specific surface area is no more than 60.5 m 2 g −1 , 25,26 resulting in a less than adequate catalytic effect. There is therefore a need for efficient and highly dispersed nanometric Ni catalysts to destabilize LiBH 4 .…”

Recent Advances in the Use of Sodium Borohydride as a Solid State Hydrogen Store

“…PXD and Raman spectroscopy reveal that mechanically activated mixtures of NaBH4 and Mg(OH)2 react yielding MgO as the only crystalline phase between 240 °C and 318 °C. Ball milled NaBH4-2Mg(OH)2 mixtures release hydrogen in one exothermic reaction, with an onset temperature of 240 °C [71]. The estimated enthalpy for the reaction is 135.9 kJ· mol −1 and the dehydrogenation products contain NaBO2 and MgO [70].…”

Theoretical prediction of nanosizing effects and role of additives in the decomposition of Mg(BH4)2

“…their decomposition is too favorable, and the re-hydrogenation process is difficult. There are many strategies to reach to best balancing between de-hydrogenation and hydrogenation cycles, such as formation of mixed borohydrides, 34 inclusion of additives, [35][36][37] nanostructuration [38][39][40] and nanoconnement. 39,40 Specically, in mixed borohydrides the stability of the bare material can be modied and tuned by combining different metals.…”