Metal-catalyzed hydrolysis of ammonia borane: Mechanism, catalysts, and challenges

The Hydrogen‐Storage Challenge: Nanoparticles for Metal‐Catalyzed Ammonia Borane Dehydrogenation

“…Noble transition metals like rhodium, [36] ruthenium, [37] platinum, [38] palladium, [39] and silver, [40] as well as non-noble metals like nickel, [41] cobalt, [42] copper, [43] iron, [44] and various composite multimetallic systems (from bimetallic [45] up to tetrametallic [46] ) have been reported as highly active for AB dehydrogenation. Heterogeneous catalysts can be in the form of nonsupported nanoparticles, [29,47,48] nanoparticles supported on inorganic oxides (silica, [31,49] alumina, [31,50] ceria, [36,51] TiO 2 , [52] etc. ), on carbon allomorphs [53] (carbon nanotubes CNTs, [38,54,55] graphene, [37,56] graphene oxide derivatives, [57,58] nanodiamond ND, [59] etc.…”

Catalytic Behavior of Iron-Containing Cubic Spinel in the Hydrolysis and Hydrothermolysis of Ammonia Borane

“…The high activity cannot also be related to the presence of coarsely dispersed metallic copper. On the contrary, it is the low-active samples CuFe-4 and CuFe-5 that contain a considerable amount of reduced copper (15-18 wt%) (11), a high content of Fe 2 O 3 (13), a low content of the spinel (5) and a Cu 2 O impurity (9). According to XRD, the value of CSR of Cu 0 formed upon the combustion is >150 nm (Table 2), which substantially exceeds the CSR of the active copper forming from the oxides in the reaction medium of ammonia borane (≤40 nm) [25]; this seems to be responsible for the low activity of such samples.…”

“…Ammonia borane (NH 3 BH 3 , AB) is an extensively studied hydride and dozens of review articles have already appeared discussing the results of these studies [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 ]. The high hydrogen content of this hydride (19.6 wt%) allows it to be applied in a variety of fields: as hydrogen storage systems to generate hydrogen for the needs of hydrogen economy [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 ], as a component of fuels [ 11 , 12 ], as a reducing agent in fine organic synthesis [ 13 ] and in the synthesis of metallic nanoparticles [ 14 , 15 ].…”

“…This process is traditionally carried out in an excess of water at room temperature in the presence of various catalysts [ 8 , 9 , 10 , 18 , 19 ]. Because of the high content of water, this process has a low value of gravimetric hydrogen density (GHD < 1 wt%), which is calculated using the ratio of the mass of released hydrogen to the total mass of all reactants and components of the hydrogen-generating system.…”

Synergistic effect of Co catalysts with atomically dispersed CoNx active sites on ammonia borane hydrolysis for hydrogen generation

“…Numerous precious metal catalysts have been documented to efficiently release the theoretical three equivalents of hydrogen from ammonia borane, and this has been the subject of several reviews. 4,5 However, due to their high cost and rare abundance, research has been directed towards the search for non-precious metal catalysts with high catalytic activity and stability. In particular, both unsupported and supported cobalt (Co) and Co-based catalysts have attracted considerable attention due to their modest activities, high abundance, lower prices (Co: V 26.6 per kg vs. Ir: V 52 750 per kg) and magnetic nature which facilitate catalysts' recovery.…”