Hydrogen generation from hydrolysis of NH3BH3 by an electroplated Co–P catalyst

This paper investigates the effect of an electroplated Co–P catalyst on hydrogen generation kinetics from hydrolysis of NH₃BH₃. The Co–P catalyst is composed of an amorphous Co–P phase and Co nanoparticles. An increase in NH₃BH₃ concentration caused the hydrogen generation rate to increase dramatically. The Co–P catalyst shows a large hydrogen generation rate for 2 wt% NH₃BH₃ solution at 30 °C. This is 1.8 times higher than that of the Pt/C catalysts and 6 times higher than that of Ru catalysts. The activation energy for hydrolysis of NH₃BH₃ by the Co–P catalyst is calculated to be 22 kJ/mol, which is close to that of noble metal-based catalysts.     

Hydrogen release by thermolysis of ammonia borane NH3BH3 and then hydrolysis of its by-product [BNHx]

Ammonia borane (AB) is one of the most attractive hydrides owing to its high hydrogen density (19.5 wt%). Stored hydrogen can be released by thermolysis or catalyzed hydrolysis, both routes having advantages and issues. The present study has envisaged for the first time the combination of thermolysis and hydrolysis, AB being first thermolyzed and then the solid by-product believed to be polyaminoborane [NH₂BH₂]_n (PAB) being hydrolyzed. Herein we report that: (i) the combination is feasible, (ii) PAB hydrolyzes in the presence of a metal catalyst (Ru) at 40 °C, (iii) a total of 3 equiv. H₂ is released from AB and PAB-H₂O, (iv) high hydrogen generation rates can be obtained through hydrolysis, and (v) the by-products stemming from the PAB hydrolysis are ammonium borates. The following reactions may be proposed: AB → PAB + H₂ and PAB + xH₂O → 2H₂ + ammonium borates. All of these aspects as well as the advantages and issues of the combination of AB thermolysis and PAB hydrolysis are discussed.     

Aluminum chloride for accelerating hydrogen generation from sodium borohydride

The present research paper reports preliminary results about the utilization of anhydrous aluminum chloride (AlCl₃) for accelerating hydrogen generation through hydrolysis of aqueous solution of sodium borohydride (NaBH₄) at 80 °C. To the best of our knowledge, AlCl₃ has never been considered for that reaction although many transition metal salts had already been assessed. AlCl₃ reactivity was compared to those of AlCl₃·6H₂O, AlF₃, CoCl₂, RuCl₃ and NiCl₂. With AlCl₃ and a NaBH₄ solution having a gravimetric hydrogen storage capacity (GHSC) of 2.9 wt.%, almost 100% hydrogen was generated in few seconds, i.e., with a hydrogen generation rate (HGR) of 354 L min⁻¹ g⁻¹(Al). This HGR is one of the highest rates ever reported. Higher HGRs were obtained by mixing AlCl₃ with CoCl2, RuCl₃ or NiCl₂. For example, the system RuCl₃:AlCl₃ (50:50 mass proportion) showed a HGR > 1000 L min⁻¹ g⁻¹(Ru:Al). The hydrolysis by-products (once dried) were identified (by XRD, IR and elemental analysis) as being Al(OH)₃, NaCl and Na₂B(OH)₄Cl and it was observed that even in situ formed Al(OH)₃ has catalytic abilities with HGRs of 5 L min⁻¹ g⁻¹(Al). All of these preliminary results are discussed, which concludes that AlCl₃ has a potential as accelerator for single-use NaBH₄-based storage system.     

Method to release hydrogen from ammonia borane for portable fuel cell applications

Ammonia borane (AB, NH₃BH₃) is considered to be a promising hydrogen storage material as it contains 19.6 wt% hydrogen. It is difficult, however, to release hydrogen from AB. Thermolysis, catalytic hydrolysis and heat generated by additional reactive mixtures are usually employed, but these methods have disadvantages that limit their use for portable applications. In this paper, we demonstrate a new approach to release hydrogen, which does not require any catalyst and produces relatively high hydrogen yield and environmentally benign byproducts. It involves nano-aluminum (nAl)/water combustion reaction, which provides heat for AB dehydrogenation and releases additional hydrogen from water. To facilitate higher H₂ yield from thermolysis, as compared to hydrolysis, AB is spatially separated from the nAl/water mixture using a concentric cylindrical container. The effect of the container design on hydrogen generation is studied and optimized. This study also includes transient temperature and pressure measurements, and product characterization using mass spectrometer and ¹¹B NMR. This approach provides H₂ yield up to 9.5 wt% on material basis. Our experimental results and analysis show that a proposed power source based on this method is promising for portable electronic devices.     

Hydrogen generation from hydrolysis of NH3BH3/MH (M = Li,Na) binary hydrides

Hydrogen release from hydrolysis of LiNH₂BH₃, NaNH₂BH₃, LiH–NH₃BH₃ and NaH–NH₃BH₃ respectively was investigated in this paper. It is shown experimentally that LiNH₂BH₃ and NaNH₂BH₃ hydrolysis can release 3 equiv. of hydrogen at 25 °C. Hydrolysis of LiNH₂BH₃ or NaNH₂BH₃ exhibits greatly improved kinetics in comparison with neat NH₃BH₃ hydrolysis. The electronic and structural changes from NH₃BH₃ to [NH₂BH₃]⁻ play a crucial role in the improvements. The mechanism of LiNH₂BH₃ and NaNH₂BH₃ hydrolysis is the combination of H⁺ and OH⁻ ions of water with the polar ions of LiNH₂BH₃ and NaNH₂BH₃. The process of LiH–NH₃BH₃ and NaH–NH₃BH₃ hydrolysis comprises two steps: LiH or NaH first reacts with water and then the generated heat initiates thermohydrolysis of NH₃BH₃. LiH or NaH hydrolysis is prior to the reaction of LiH or NaH with NH₃BH₃. Our results show a novel strategy to promote hydrogen release kinetics of LiNH₂BH₃ and NaNH₂BH₃. Furthermore, our results also present a novel noncatalytic method for hydrogen release from NH₃BH₃ by co-hydrolyzing it with other highly exothermic hydrides.     

High-capacity hydrogen release through hydrolysis of NaB3H8

NaB₃H₈ has advantages over NaBH₄ and NH₃BH₃, two most widely studied chemical hydrides for hydrogen storage via hydrolysis. NaB₃H₈ has an extraordinary high solubility in water and thus possesses a high theoretical capacity of 10.5 wt% H via hydrolysis, in contrast to 7.5 wt% for NaBH₄ and 5.1 wt% for NH₃BH₃. NaB₃H₈ is reasonably stable in water which makes it unnecessary to add corrosive NaOH as a stabilizer as the case for NaBH₄. Furthermore, hydrolysis of NaB₃H₈ can be catalyzed by a Co-based catalyst with fast kinetics that is comparable to Ru-based catalysts. Therefore, cost-effective hydrolysis of NaB₃H₈ is possible for practical applications. A high capacity of 7.4 wt% H was achieved when water was included in the materials weight.     

Room temperature hydrogen generation from aqueous ammonia-borane using noble metal nano-clusters as highly active catalysts

Nano-clusters of noble metals Ru, Rh, Pd, Pt and Au have been supported on γ-Al₂O₃, C and SiO₂, of which the catalytic activities have been investigated for hydrolysis of NH₃BH₃. Among these catalysts, the Ru, Rh and Pt catalysts exhibit high activities to generate stoichiometric amount of hydrogen with fast kinetics, whereas the Pd and Au catalysts are less active. Support effect has been studied by testing the hydrogen generation reaction in the presence of Pt supported on γ-Al₂O₃, VULCAN^® carbon and SiO₂, and it is found that Pt on γ-Al₂O₃, which has the smallest particle size, is the most active. Concentration dependence of the hydrogen generation from aqueous NH₃BH₃ solutions has been investigated in the presence of Pt/γ-Al₂O₃ by keeping the amount of Pt/γ-Al₂O₃ catalyst unchanged, which exhibits that the hydrogen release versus time (ml H₂ min⁻¹) does not significantly change with increasing the NH₃BH₃ concentration, indicating that the hydrogen release rate is not dependent on the NH₃BH₃ concentration and the high activity of the Pt catalyst can be kept at high NH₃BH₃ concentrations. Activation energies have been measured to be 23, 21 and 21 kJ mol⁻¹ for Ru/γ-Al₂O₃, Rh/γ-Al₂O₃ and Pt/γ-Al₂O₃ catalysts, respectively, which may correspond to the step of B–N bond breaking on the metal surfaces. The particle sizes, surface morphology and surface areas of the catalysts have been obtained by TEM and BET experiments.     

Achievement of excellent hydrogen sorption through swift hydrogen transport in 1:2 Mg(NH2)2–LiH catalyzed by Li4BH4(NH2)3and carbon nanostructures

The present studies deal with the catalytic character of carbon nanostructure (Graphene (Gr) and single-wall carbon nanotubes (SWNTs), and their composite versions) on the hydrogen sorption behavior of 1:2 Mg(NH₂)₂–LiH/Li₄BH₄(NH₂)₃. The inclusion of an optimal quantity of 2 wt% SWNTs in Mg(NH₂)₂–2LiH/Li₄BH₄(NH₂)₃ resulted in superior hydrogen sorption over 2 wt% Gr and 2 wt% of (Gr and SWNT) composite. The onset desorption temperature for SWNTs catalyzed Mg(NH₂)₂–2LiH/Li₄BH₄(NH₂)₃ is 108 °C which is 32 °C, 44 °C lower compared to Gr catalyzed Mg(NH₂)₂–2LiH/Li₄BH₄(NH₂)₃ and uncatalyzed Mg(NH₂)₂–2LiH/Li₄BH₄(NH₂)₃ respectively. The de/re-hydrogenation kinetics of the SWNT catalyzed sample has been found to be 4.02 wt% and 4.63 wt% within 15min at 170 °C and 7 MPa H₂ pressure, correspondingly. The activation energy for SWNT catalyzed Mg(NH₂)₂–2LiH/Li₄BH₄(NH₂)₃ has been found to be 69.75 kJ/mol. The SWNT catalyzed Mg(NH₂)₂–2LiH/Li₄BH₄(NH₂)₃ shows good cyclic stability (almost no degradation) up to 10 cycles. The better hydrogen sorption for SWNTs is attributed to the ballistic transport of hydrogen atoms within and across the amide/hydride matrix. In contrast, Gr sheets agglomerate, which adversely affects hydrogen sorption from Gr and Gr+SWNT composites. A hydrogen sorption mechanism has been proposed based on structural, microstructural, Fourier-transform infrared spectroscopy, and Raman characterization results.     

Magnesium borohydride hydrolysis with kinetics controlled by ammoniate formation

The possibility of hydrogen generation by hydrolysis of magnesium borohydride and its ammoniates was explored. Results show that catalyst-free Mg(BH₄)₂ can generate 1700 mL (H₂)·g⁻¹ in 1 min, 2760 mL (H₂)·g⁻¹ in 2 h, and 3004 mL (H₂)·g⁻¹ in 5 h without any diborane (B₂H₆) emission. Mg(BH₄)₂ presents the highest hydrogen yield reported to date. However, the hydrogen generation rate of Mg(BH₄)₂ may be too fast to be controllable in some hydrogen production cases. Therefore, NH₃ was added to form ammoniates to further regulate the hydrogen supply kinetics of Mg(BH₄)₂. The hydrogen yields of Mg(BH₄)₂·0.5NH₃, Mg(BH₄)₂·NH₃, Mg(BH₄)₂·2NH₃, Mg(BH₄)₂·3NH₃ and Mg(BH₄)₂·6NH₃ are 2376, 2029, 1780, 1665 and 1180 mL (H₂) g⁻¹, respectively, which demonstrates a well-controlled hydrogen supply rate. These results indicate that catalyst-free Mg(BH₄)₂ and its ammoniates have good hydrolysis performance and show promise as convenient high-density hydrogen generation materials.     

Cesium hydrazinidoborane,the last of the alkali hydrazinidoboranes,studied as potential hydrogen storage material

Alkali hydrazinidoboranes MN₂H₃BH₃ (M = Li, Na, K, Rb) have been developed for hydrogen storage. To complete the family of MN₂H₃BH₃, we focused on cesium hydrazinidoborane CsN₂H₃BH₃ (CsHB). It has been synthesized by reaction of cesium with hydrazine borane (N₂H₄BH₃) at −20 °C under inert atmosphere, and it has been characterized. A crystalline solid (monoclinic, s.g. P2₁ (No. 4)) has been obtained. Its potential for hydrogen storage has been studied by combining different techniques. It was found that, under heating at constant heating rate (5 °C min⁻¹) or at constant temperature (e.g. 120 °C), CsHB decomposes rather than it dehydrogenates. It releases several unwanted gaseous products (e.g. NH₃, B₂H₆) together with H₂, and transforms into a residue that poses safety issues because of shock-sensitivity and reactivity towards O₂/H₂O. Though the destabilization brought by Cs⁺ onto the anion [N₂H₃BH₃]⁻ has been confirmed, the effect is not efficient enough to avoid the aforementioned drawbacks. All of our results are presented herein and discussed within the context of solid-state hydrogen storage.     

Effect of boric acid on thermal dehydrogenation of ammonia borane: Mechanistic studies

Ammonia borane (AB, NH₃BH₃) is a promising hydrogen storage material for use in proton exchange membrane (PEM) fuel cell applications. In this study, the effect of boric acid on AB dehydrogenation was investigated. Our study shows that boric acid is a promising additive to decrease onset temperature as well as to enhance hydrogen release kinetics for AB thermolysis. With heating, boric acid forms tetrahydroxyborate ion along with some water released from boric acid itself. It is believed that this ion serves as Lewis acid which catalyzes AB dehydrogenation. Using boric acid, we obtained high H₂ yield (11.5 wt% overall H₂ yield, 2.23 H₂ equivalent) at 85 °C, PEM fuel cell operating temperatures, along with rapid kinetics. In addition, only trace amount of NH₃ (20–30 ppm) was detected in the gaseous product. The spent AB solid product was found to be polyborazylene-like species. The results suggest that the addition of boric acid to AB is promising for hydrogen storage, and could be used in PEM fuel cell based vehicles.     

Manganese oxide octahedral molecular sieves stabilized Rh nanoparticles for the hydrogen production from the ethylenediamine-bisborane hydrolysis

Ethylenediamine-bisborane (C₂H₁₄B₂N₂, BH₃NH₂CH₂CH₂NH₂BH₃, EDB), an important carbon derivative of ammonia-borane (AB), has come to the fore in recent years due to some disadvantages that limit the practical use of AB for the applications of hydrogen storage. EDB is a very promising chemical hydrogen storage material in the solid crystal form at room temperature, with a hydrogen content of 16.3% by weight, which decomposes rapidly at temperatures above 363 K. Despite all these superior features, studies on catalytic systems that catalyze the hydrogen production from the EDB are very few. In the present study, we report the synthesis, characterization, and application of manganese oxide octahedral molecular sieves (OMS-2) stabilized Rh nanoparticles (Rh@OMS-2) as highly efficient and reusable catalysts for the hydrogen production from the hydrolysis of EDB. The results of characterization using P-XRD, XPS, FT-IR, SEM, SEM-elemental mapping, TEM, HR-TEM, and ICP-OES disclose that Rh (0) nanoparticles were well spread on the surface of OMS-2 nanorods. Rh@OMS-2 showed a record catalytic activity in EDB hydrolysis with an initial turn-over frequency of 102.95 min^?1 (6177 h^?1) at 25 ± 0.1 °C, the highest value ever reported for the hydrolysis of EDB. In addition, the fact that the Rh@OMS-2 catalyst kept its initial activity at the end of the 7th cycle in the hydrolysis of EDB showed that the Rh@OMS-2 was reusable and stable heterogeneous catalyst in this catalytic transformation.     

Hydrogen generation by hydrolysis of ammonia borane with a nanoporous cobalt-tungsten-boron-phosphorus catalyst supported on Ni foam

In this study, quaternary cobalt-tungsten-boron-phosphorus porous particles supported on Ni foam (Co-W-B-P/Ni), which are prepared through ultrasonification-assisted electroless deposition route, have been investigated as the catalyst for hydrogen generation (HG) from hydrolysis of ammonia borane (NH₃BH₃, AB). Compared with Ni-supported binary Co-B and ternary Co-W-B catalysts, the as-synthesized Co-W-B-P/Ni shows a higher HG rate. To optimize the preparation parameters, the molar ratio of NaBH₄/NaH₂PO₂·H₂O (B/P) and the concentration of Na₂WO₄·2H₂O (W) have been investigated and the catalyst prepared with B/P value of 1.5 and W concentration of 5 g L⁻¹ shows the highest activity. The results of kinetic studies show that the catalytic hydrolysis of AB is first order with respect to the catalyst and AB concentrations. By using the quaternary catalyst with a concentration of 0.5 wt % AB, a HG rate of 4.0 L min⁻¹ g⁻¹ is achieved at 30 °C. Moreover, the apparent activation energy for the quaternary catalyst is determined to be 29.0 kJ mol⁻¹, which is comparable to that of noble metal-based catalysts. These results indicate that the Co-W-B-P/Ni is a promising low-cost catalyst for on-board hydrogen generation from hydrolysis of borohydride.     

Epoxy-activated acrylic particulate polymer-supported Co–Fe–Ru–B catalyst to produce H2 from hydrolysis of NH3BH3

Epoxy-activated acrylic particulate polymer, namely Eupergit CM, supported Co–Fe–Ru–B catalyst (EP/Co–Fe–Ru–B) for the first time was used to produce H₂ from hydrolysis of NH₃BH₃. The EP/Co–Fe–Ru–B showed very effective performance in the production of H₂ from the hydrolysis of NH₃BH₃. Various techniques such as XRD, SEM-EDS, ICP-OES, and TEM have been used to characterize these catalysts. The parameters on the hydrolysis reaction of NH₃BH₃ such as the effect of metal amount, the effect of Ru percentage, the effect of NH₃BH₃ concentration, the effect of NaOH concentration, the amount of catalyst, temperature, and catalyst durability were investigated in detail. Eupergit CM based polymer support and Ru particles have been found to be highly effective in H₂ production reactions. The hydrogen production rate (HGR) of the EP/Co–Fe–Ru–B catalyst was found to be 36,978 mL/min/g_cat, which was quite good compared to the values reported in the literature. In addition, the activation energy (Ea) of the polymer-supported Co–Fe–Ru–B catalyst was determined as 24.91 kJ/mol.     

Enhanced low temperature hydrogen desorption properties and mechanism of Mg(BH4)2 composited with 2D MXene

Mg(BH₄)₂ occupies a large hydrogen storage capacity of 14.7 wt%, and has been widely recognized to be one of the potential candidates for hydrogen storage. In this work, 2D MXene Ti₃C₂ was introduced into Mg(BH₄)₂ by a facile ball-milling method in order to improve its dehydrogenation properties. After milling with Ti₃C₂, Mg(BH₄)₂–Ti₃C₂ composites exhibit a novel “layered cake” structure. Mg(BH₄)₂ with greatly reduced particle sizes are found to disperse uniformly on Ti₃C₂ layered structure. The initial dehydrogenation temperature of Mg(BH₄)₂ has been decreased to 124.6 °C with Ti₃C₂ additive and the hydrogen liberation process can be fully accomplished below 400 °C. Besides, more than 10.8 wt% H₂ is able to be liberated from Mg(BH₄)₂–40Ti₃C₂ composite at 330 °C within 15 min, while pristine Mg(BH₄)₂ merely releases 5.3 wt% hydrogen. Moreover, the improved dehydrogenation kinetics can be retained during the subsequent second and third cycles. Detailed investigations reveal that not only Ti₃C₂ keeps Mg(BH₄)₂ particles from aggregation during de/rehydrogenation, but also the metallic Ti formed in-situ serves as the active sites to catalyze the decomposition of Mg(BH₄)₂ by destabilizing the B–H covalent bonds. This synergistic effect of size reduction and catalysis actually contributes to the greatly advanced hydrogen storage characteristics of Mg(BH₄)₂.     

Borohydride in ionic liquids for tailored hydrogen release

H₂ as an environmentally benign energy carrier could answer the world's continuously increasing demand for sustainable energy sources, especially in portable fuel cell applications. Thereby, H₂ storage is the key issue. In the present work, we developed a liquid H₂ storage material based on BH₄^? and ionic liquids for tailored H₂ release under ambient conditions using various catalysts as releasing agents. Thereto, we synthesized four BH₄^? ionic liquids via ionic exchange. The most promising BH₄^? based ionic liquids are 1-Ethyl-3-methylimidazolium BH₄^? and 1-Propyl-3-methylimidazolium BH₄^?, containing up to 3 wt% releasable hydrogen and the latter being liquid at standard temperature. The hydrolysis of 1-Ethyl-3-methylimidazolium BH₄^? with various supported metal catalysts (Pt/C, Pt/CNT, Ru/CNT, Pd/CNT, 5 wt% metal) and H₂O (8, 16, 24 eq.) was assayed. The highest yield was obtained with 24 eq. H₂O and Pt/CNT. The catalysts were characterized via X-ray photoelectron spectroscopy and transmission electron microscopy/energy-dispersive X-ray spectroscopy. To calculate the catalyst activities, the dispersion and size distribution of the metal particles were determined. Recycling of Pt/CNT showed a reasonable stability of the catalyst activity over four recycling runs. In order to avoid spontaneous crystallization of 1-Ethyl-3-methylimidazolium BH₄^? as a storage material, 1-Propyl-3-methylimidazolium BH₄^? was introduced. The hydrolysis yield was significantly increased by the use of acidic catalysts, such as HCl and Amberlyst 36. Further enhancement of the H₂ yield was achieved by adopting a semi batch process, continuously adding 1 M HCl to 1-Propyl-3-methylimidazolium BH₄^?. The H₂ release correlated approximately linearly with the acid addition rate, excluding liquid-liquid mass transfer limitations during the hydrolysis. Based on ¹¹B NMR analysis, a reaction mechanism of the hydrolysis of BH₄^? ionic liquid with HCl as catalyst is proposed.     

Thermal dehydrogenation behaviors and mechanisms of Mg(BH4)2∙6NH3-xLiH combination systems

A reactive composite of Mg(BH₄)₂⋅6NH₃-xLiH is prepared, and the effects of the LiH content on the dehydrogenation/hydrogenation properties of the material are investigated. The results show that the presence of LiH with x = 3 reduces the onset dehydrogenation temperature of Mg(BH₄)₂⋅6NH₃ from 130 °C to 80 °C in TPD mode. Approximately 14.3 wt% hydrogen is released from the Mg(BH₄)₂⋅6NH₃-6LiH composite with distinctly reduced ammonia evolution while heating to 340 °C. Upon heating, Mg(BH₄)₂⋅6NH₃ first reacts with LiH to form Mg(NH₂)₂, Li₃BN₂H₈ and LiBH₄ with the release of H₂ and the evolution of a minor amount of NH₃. The newly formed Mg(NH₂)₂ then reacts with LiH to produce H₂ and Li₂Mg(NH)₂. Further elevating the operating temperature induces chemical reactions between Li₂Mg(NH)₂, LiBH₄ and Li₃BN₂H₈, causing the release of additional H₂ and production of Li₃BN₂, LiMgBN₂ and LiH. The dehydrogenated sample at 210 °C absorbs 2.2 wt% of hydrogen, exhibiting partial reversibility for hydrogen storage.     

Simple synthesis of Cu2O–CoO nanoplates with enhanced catalytic activity for hydrogen production from ammonia borane hydrolysis

The development of inexpensive and high performing catalysts for ammonia borane (NH₃BH₃) hydrolysis is crucial for hydrogen production. In our research, a high-performance plate-like Cu₂O–CoO nanocomposite catalyst for NH₃BH₃ hydrolysis has been developed for the first time. In the hydrolytic reaction, both Cu₂O and CoO are separately inactive, while Cu₂O–CoO nanoplates show a high turnover frequency of 34.1 mol_hydrogen min⁻¹ mol_cat⁻¹, which is attributed to the synergistic effect between Cu₂O and CoO. It is interesting to discover that the induction time for the hydrolytic reaction is reduced to null when a small amount of Cu₂O is introduced into CoO. The reaction kinetics of NH₃BH₃ hydrolysis catalyzed by Cu₂O–CoO is also investigated. This work may provide other researchers some valuable insights into designing inexpensive and synergistic catalysts with enhanced catalytic activity for NH₃BH₃ hydrolysis for hydrogen production.     

Characterization of hydrogen generation for fuel cells via borane hydrolysis using an electroless-deposited Co-P/Ni foam catalyst

The effect of an electroless-deposited Co-P/Ni foam catalyst on H₂ generation kinetics in ammonia borane (NH₃BH₃) solution and the cyclic behaviour (durability) of the catalyst are investigated. The electroless-deposited Co-P is composed of an inner flat layer and outer layer that consists of an aggregate of spherical particles. The H₂ generation rate/projected area of the Co-P/Ni foam catalyst is much higher than that of a Co-P/Cu sheet catalyst. The activation energy (E_a) for the hydrolysis of NH₃BH₃ using the Co-P/Ni foam catalyst is calculated to be 48 kJ mol⁻¹. After the first cycle, the H₂ generation rate decreases dramatically, i.e., by 16%, due to a decrease in surface area caused by the partial separation of spherical Co-P particles. Between the first and sixth cycles, the H₂ generation rate decreases gradually (by 14%) on account of a decrease in the number of P atoms that create active metallic Co sites on catalytic surface. After six cycles, about 70% of the initial H₂ generation rate remains constant. The study reveals a promising means of hydrogen generation for polymer electrolyte membrane fuel cells.     

Releasing 9.6 wt% of H2 from Mg(NH2)2–3LiH–NH3BH3 through mechanochemical reaction

Ball milling the mixture of Mg(NH₂)₂, LiH and NH₃BH₃ in a molar ratio of 1:3:1 results in the direct liberation of 9.6 wt% H₂ (11 equiv. H), which is superior to binary systems such as LiH–AB (6 equiv. H), AB–Mg(NH₂)₂ (No H₂ release) and LiH–Mg(NH₂)₂ (4 equiv. H), respectively. The overall dehydrogenation is a three-step process in which LiH firstly reacts with AB to yield LiNH₂BH₃ and LiNH₂BH₃ further reacts with Mg(NH₂)₂ to form LiMgBN₃H₃. LiMgBN₃H₃ subsequently interacts with additional 2 equivalents of LiH to form Li₃BN₂ and MgNH as well as hydrogen.