Ammonia Borane Hydrolysis Reaction Research Articles

Controllable preparation of Co-based catalysts doped with Cu and Mo for boosting hydrogen evolution

Hydrogen evolution from ammonia borane hydrolysis is a promising way for utilization of clean energy. Development of efficient and stable non-noble catalysts for improvement of hydrogen generation rate is essential but still a challenge. Herein, the heterostructured Co-based catalysts were controllably designed by combining the synergistic effect with oxygen vacancy engineering to improve the hydrogen generation rate. CoCu1Mo3-NC-O-15 exhibits the TOF value of 24.44 min−1 at 298 K with addition of 0.44 M NaOH, which is nearly 68 times that of Co-NC. The activation energy over CoCu1Mo3-NC-O-15 is 28.44 kJ mol−1. The CoCu1Mo3-NC-O-15 catalyst presents the good stability in ammonia borane hydrolysis reaction due to the carbon-coated structure. The strong synergistic effect and oxygen vacancy are favorable to the adsorption and dissociation of NH3BH3 and H2O molecules, leading to an astonishing improvement of catalytic activity. This study provides a novel way to design the heterostructured catalysts and a rational way to boost the dehydrogenation rate from AB.

Magnetically isolable Pd(0) nanoparticles supported on surface functionalized Fe3O4 for hydrogen generation via ammonia borane hydrolysis

AbstractPd(0) nanoparticles supported on surface functionalized magnetite (Fe3O4/SiO2‐NH2/HB@Pd) were prepared as catalyst for hydrolysis of ammonia borane (AB). The obtained magnetic nanocomposite material was seperated from the reaction media through a permanent magnet and characterized by FT‐IR, XRD, SEM‐EDX, TEM, ICP‐OES and XPS techniques. 100 mg Fe3O4/SiO2−NH2/HB@Pd nanocomposite with Pd metal content of 6.00±0.14 catalyzed the hydrolysis of 10 mM AB at 25 °C with 100 % yield. The presented work includes the effect of catalyst amount and temperature on the rate of the hydrolysis reaction of AB. As a result of the kinetic studies, the activation energy (Ea) for the Fe3O4/SiO2−NH2/HB@Pd catalyzed AB hydrolysis reaction was calculated as 34±1 kJ.mol−1, and the TOF value was calculated as 133 mol H2.(mol Pd(0).h)−1. The designed heterogenous magnetic nanocomposite catalyst demonstrated significant catalytic activity for AB hydrolysis reaction at 25 °C.

Rapid preparation of Ru(0) nanoparticles stabilized with water-soluble biopolymer for hydrogen production from ammonia borane: Development of battery-like hydrolysis media

The biohybrid Na-Alg@Ru catalyst was prepared as a result of stabilizing Ru(0) nanoparticles with biopolymer chains of sodium alginate. The in-situ prepared Ru(0) nanoparticles had an average particle size of 1.023 ± 0.097 nm. The monodisperse Ru(0) nanoparticles prepared with a very practical, inexpensive and rapid method were used as a catalyst in hydrogen production by the hydrolysis reaction of ammonia borane (AB). The Na-Alg@Ru catalyst containing 3 mg Ru(0) metal catalyzed the hydrolysis of 50 mM AB with 100% yield, and the activation energy (Ea) of the reaction was estimated as 61.05 kJ mol−1. In addition, the Na-Alg@Ru nanoparticles were prepared with acrylamide as p(AAm)/Na-Alg@Ru hydrogel films suitable for use in hydrogen production in fuel cells, which represents a battery-like environment, and used for hydrogen production from AB. Thus, it was shown that the catalysts prepared in a few nm size could easily be used in battery-like environments.

Nitrogen doping excited Ru and Ti3C2−xNx support for hydrogen generation from ammonia borane

The research and development of efficient catalysts is very important for the sustainable utilization of hydrogen energy. Herein, we designed the Ru/Ti3C2−xNx catalysts using N-doped two-dimensional material MXene (Ti3C2−xNx) as support toward hydrogen generation from ammonia borane (AB) hydrolysis. Due to the confinement and anchoring effects of Ti3C2−xNx, the as-prepared Ru/Ti3C2−xNx catalysts show an ultrafine particle size of 1.55 nm and remarkable AB hydrolysis activity with high turnover frequency (TOF) value of 1334 min−1 and rB value of 297 × 103 mL·min−1·gRu−1 at 298 K. XPS results show that the doped N atoms in Ti3C2−xNx support provide electron-feeding effect for Ru in the reaction to form electron-rich Ru. The isotope experiments confirm that the dissociation of H2O is the rate-determining step (RDS) in AB hydrolysis reaction catalyzed by Ru/Ti3C2−xNx. According to the density functional theory (DFT) calculations, the N atoms introduced into Ti3C2−xNx decrease the dissociation energy of O–H bond in H2O molecules, accelerating the desorption of H* from Ti3C2−xNx surface. This research provides a strategy to enhance synergistic interaction between support and metal through N-doping, so as to effectively improve the catalytic performance of heterogeneous catalysts.

Highly active Fe36Co44 bimetallic nanoclusters catalysts for hydrolysis of ammonia borane: The first-principles study

In this paper, Fe36Co44 nanocluster structure is used to catalyze the hydrolysis reaction of ammonia borane to produce H2. Firstly, we complete the construction of Fe36Co44 cluster structure and calculate the electronic properties of the cluster. By comparing the adsorption process of Ammonia Borane (AB) in active sites of the cluster, which have different Effective Coordination Number (ECN), the qualitative relationship between ECN and the catalytic activation of AB is clarified, and the optimal catalytic active site is obtained. Then, from the perspective of different reaction paths, we study the hydrolysis reaction of AB in multiple paths, and obtain 5 different reaction paths and energy profiles. The calculation results show that in the case of NH bond priority break (path 5), the reaction has the minimum rate-determining step (RDS) barrier (about 1.02 eV) and the entire reaction is exothermic (about 0.40 eV). So, path 5 is an optimal catalytic reaction path. This study will have an important guiding significance for the study of the AB hydrolysis reaction mechanism.

Enhanced hydrogen generation by reverse spillover effects over bicomponent catalysts

The contribution of the reverse spillover effect to hydrogen generation reactions is still controversial. Herein, the promotion functions for reverse spillover in the ammonia borane hydrolysis reaction are proven by constructing a spatially separated NiO/Al2O3/Pt bicomponent catalyst via atomic layer deposition and performing in situ quick X-ray absorption near-edge structure (XANES) characterization. For the NiO/Al2O3/Pt catalyst, NiO and Pt nanoparticles are attached to the outer and inner surfaces of Al2O3 nanotubes, respectively. In situ XANES results reveal that for ammonia borane hydrolysis, the H species generated at NiO sites spill across the support to the Pt sites reversely. The reverse spillover effects account for enhanced H2 generation rates for NiO/Al2O3/Pt. For the CoOx/Al2O3/Pt and NiO/TiO2/Pt catalysts, reverse spillover effects are also confirmed. We believe that an in-depth understanding of the reverse effects will be helpful to clarify the catalytic mechanisms and provide a guide for designing highly efficient catalysts for hydrogen generation reactions.

Nano-casting procedure for catalytic cobalt oxide bead preparation from calcium-alginate capsules: Activity in ammonia borane hydrolysis reaction

The preparation of bead type catalysts, which had a rapid and easy recoverable property for reusability and regeneration procedures during ammonia borane (NH3BH3) hydrolysis, was the main scope of this study. In the present study, the nano-casting procedure was adapted to cobalt oxide (Co3O4) microbeads preparation by multi-step ions exchange procedures. By nano-castings -, cobalt-alginate capsules provided the formation of a surface-active bead (140 ± 0.4 μm) in Co3O4 nanoparticles (25–35 nm) with enhanced performance for releasing of hydrogen from NH3BH3. Moreover, the catalysts used for 555 min without any mechanical damages during reusability tests and regeneration procedure. The bead type catalyst enabled the rapid and easy recover at the end of the reaction that improved the reuse of catalysts for the practical and curial for a commercial on-board hydrogen production application.

Synthesis of a Novel Co-B/CTAB Catalyst via Solid-state-reaction at Room Temperature for Hydrolysis of Ammonia-borane

Cobalt-boride(Co-B) is emerging as one of the promising materials in the base-hydrolytic dehydrogenation of ammonia-borane(AB). In order to avoid the low specific area and poor catalytic capacity of Co-B catalyst caused by aggregation arising from the strong reducing property and rapid reaction condensation of sodium borohydride(NaBH4), novel cobalt boride/cetyltrimethylammonium bromide(Co-B/CTAB) catalyst was obtained via solidstate grinding at room temperature, and the catalyst was further characterized by XRD, SEM, XPS and BET. The hydrogen generation rate(HGR) was then determined by the hydrolysis reaction of AB. The SEM images indicate that a lot of irregular folds and curled edges are formed on the sample with a maximum surface area of 145.57 m2/g, thus possibly resulting in the high hydrogen production(HGR was 10.68 L·min−1·g−1), which may be attributed to CTAB that provide favorable large specific surface area and abundant porous structure. Additionally, catalyst will not be affected by solvants during solid-state reaction. As a diluent, the surfactant CTAB hindered the reaction rate of sodium borohydride reduction to cobalt boride and obtained the novel catalyst with a large specific surface area.

Synthesis and characterization of bimetallic cobalt-rhodium nanoclusters as effective catalysts to produce hydrogen from ammonia borane hydrolysis

Here, first-time synthesis and characterization of highly effective and relatively low-cost poly (N-vinyl-2-pyrrolidone)-stabilized cobalt-rhodium nanoclusters and their employment as catalysts to generate hydrogen from ammonia borane via hydrolysis pathway is reported. They are readily synthesized by co-reduction of cobalt and rhodium cations in ethanol/water mixture under reflux temperature. They are found to be highly stable for a long time without any precipitation. Their size, morphology, and chemical composition are determined by advanced analytical techniques of ultraviolet–visible (UV–Vis) electronic absorption spectroscopy, transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). They are found to be highly recyclable and effective catalysts for hydrogen release from ammonia borane hydrolysis reaction at very low concentrations and temperature, providing initial turnover frequency (TOF) of 154 min−1 and activation energy of 42.7 kJ mol−1.

Dramatic Synergy in CoPt Nanocatalysts Stabilized by “Click” Dendrimers for Evolution of Hydrogen from Hydrolysis of Ammonia Borane

Hydrolysis of ammonia borane (AB) is a very convenient source of H2, but this reaction needs catalytic activation to become practical under ambient conditions. Here this reaction is catalyzed by bimetallic late transition-metal nanoparticles (NPs) that are stabilized and activated by “click” dendrimers. Dendrimers 1 and 2 contain 27 or 81 triethylene glycol terminal groups and 9 or 27 1,2,3-triazole ligands, respectively, located on the dendritic tethers. A remarkable synergy between Pt and Co in the Pt–Co/“click” dendrimer nanocatalysts is revealed. These Pt–Co/“click” dendrimer catalysts are much more efficient for hydrolysis of AB than either “click” dendrimer-stabilized Co or Pt analogues alone. The best catalyst, Pt1Co1/1, stabilized by the nonatriazole “click” dendrimer 1 achieves a turnover frequency number (TOF) of 303 molH2 molcat–1 min–1 (606 molH2 molPt–1 min–1) at 20 ± 1 °C. The AB hydrolysis reaction catalyzed by Pt1Co1/1 is boosted by NaOH, the TOF value reaching 476.2 molH2 molcat–1 min–1 (952.4 molH2 molPt–1 min–1), one of the very best results ever obtained for this reaction. The presence of ≥25% Pt in the CoPt nanoalloy provides a reaction rate higher than that obtained with the pure PtNP catalyst alone. The kinetics involves in particular a kinetic isotope effect kD/kH of 2.46 obtained for the hydrolysis reaction with D2O, suggesting that an O–H bond of water is cleaved in the rate-determining step. Tandem reactions were carried out for the hydrogenation of styrene with hydrogen generated from the hydrolysis of AB. Performing this tandem reaction with D2O shows deuteration of the ethylbenzene products, confirming O–D bond cleavage and H/D scrambling on the bimetallic NP surface. Finally, a full reaction mechanism is proposed. This dramatic synergy type should also prove to be useful in a number of other catalytic systems.

Synergetic Effect of Sodium Borohydride Addition in Ammonia Borane Hydrolysis Reaction Mechanism and Kinetics

Synergetic effect of sodium borohydride (NaBH4) addition to ammonia borane (NH3BH3) hydrolysis reaction had been studied and iron-borate (FeB) was used to catalyze the reaction. Hydrogen generation performance of the hydrolysis reactions was compared for three different operating conditions: (1) in the presence of NaBH4 with FeB catalyst, (2) with FeB without NaBH4 addition and (3) in the presence of NaBH4 without FeB. It was found that addition of NaBH4 to the NH3BH3 hydrolysis reaction catalyzed by FeB resulted in the synergetic effect (synergetic factor (SF) > 0) and improved the hydrogen generation performance. Kinetic analysis showed that NaBH4 addition decreases the activation energy (Ea) from 52.11 ± 0.85 to 27.19 ± 0.44 kJ/mol. Simulation of hydrolysis kinetics curves indicated that addition of NaBH4 (the mole fraction of NaBH4 added to NH3BH3 is (1)) changed the three-dimensional diffusion mechanism to the one-dimensional one and brought on better hydrolysis properties in terms of higher hydrogen generation rate and lower induction time.

Alloyed palladium-nickel hollow nanospheres with interatomic charge polarization for improved hydrolytic dehydrogenation of ammonia borane

Hydrolysis reaction of ammonia borane (AB) has been considered as a safe and efficient hydrogen generation method, in which designing cost-effective and high-performance catalysts plays vital role. In this work, we have developed well dispersed palladium-nickel hollow nanospheres (PdNi HNSs) with tunable shell thickness and compositions via a facile galvanic replacement approach. The as-prepared PdNi HNSs show composition-dependent catalysis in the hydrolytic dehydrogenation of AB. The Pd84Ni16/C exhibiting sphere-shaped hollow interiors with average 70 nm particle size and 10 nm thin wall, presents the highest catalytic activity with the turnover frequency of 76.0 (mol H2 min−1 (mol Pd)−1) and the activation energy of 33.5 kJ mol−1. The superior catalytic effect of PdNi HNSs in enhancing hydrolysis efficiency of AB can be ascribed to two major factors: (1) high active surface areas of the unique hollow structure; (2) enhanced H adsorption attributed to the coupling between Pd and Ni induces polarization charges on Pd catalytic sites, which is indicated by the first-principles calculation and X-ray photoelectron spectroscopy studies. Furthermore, the catalysts exert good long-term recycling stability and catalytic activity for the hydrolytic dehydrogenation of AB. This work represents a strategy may hopefully be extended to synthesize other Pd-based hollow nanostructure with reduced Pd usage and increased catalytic active sites, and also sheds light on the exploration of utilizing interatomic interactions to regulate species adsorption/activation for highly efficient catalytic performance.

Magnetically recyclable Ni@h-BN composites for efficient hydrolysis of ammonia borane

The magnetic Ni@h-BN composites containing the uniform Ni nanoparticles supported on h-BN nanosheets have been prepared via a facile solvothermal method. The as-prepared samples show high catalytic performance for H2 generation from the ammonia borane aqueous solution, especially for the Ni@h-BN with 25.0 wt% Ni content. Moreover, the Ni@h-BN composites possess a good ferromagnetic property at room temperature, endowing them with rapid magnetic separation to recycle. The kinetics of the hydrolysis of ammonia borane over the Ni@h-BN composites were further investigated in detail. It is found that the hydrogen generation was highly dependent on the catalyst amount and the reaction temperature. The activation energy of the hydrolysis reaction of ammonia borane is found to be 47.3 kJ mol−1 over the Ni@h-BN with 25.0 wt% Ni content. Considering the good catalytic activities for H2 release, the Ni@h-BN composites are expected to find important application in fuel cells and the related fields.

Promoting hydrolysis of ammonia borane over multiwalled carbon nanotube-supported Ru catalysts via hydrogen spillover

Multi-walled carbon nanotubes were used to deposit Ru metal by electrostatic adsorption and incipient wetness impregnation methods, respectively. The electrostatic adsorption method led to small (1.8–2.5nm) and highly dispersed (0.51–0.72 dispersion) Ru metal nanoparticles. The initial hydrogen generation turnover rates over Ru catalysts with different metal particle sizes showed that ammonia borane hydrolysis reaction is structure-sensitive; large Ru particles displayed high turnover rates. Multiwalled carbon nanotube-supported Ru nanoparticles exhibit high turnover rate and low activation energy for the hydrolysis of ammonia borane because of hydrogen spillover effect associated with strong interaction between Ru metal and carbon nanotubes.

Active 3D Pd/graphene aerogel catalyst for hydrogen generation from the hydrolysis of ammonia-borane

In this work, a novel three dimensional (3D) Pd/graphene aerogel hybrid was successfully synthesized and characterized. The preparation process of the Pd/graphene aerogel was also discussed systematically. Experimental results indicated that this kind of 3D Pd/graphene aerogel hybrid exhibited excellent catalytic activity on the ammonia borane hydrolysis to release hydrogen with the turnover frequency value of 9.70 molH2molmetal−1min−1, and activation energy Ea value of 30.82 kJ/mol, which is higher than that of 2D Pd/RGO and original Pd nanoparticles. Furthermore, the abundant defects of graphene aerogel support can transfer the electrons of Pd nanoparticles to graphene aerogel due to the metal-support interaction, which is beneficial to the ammonia borane hydrolysis reaction. In addition, the pore-rich 3D Pd/graphene aerogel has offered huge effective reacting acreages for ammonia borane hydrolysis, which is helpful for its reusability.

Cobalt-Nickel-Boron Supported over Polypyrrole-Derived Activated Carbon for Hydrolysis of Ammonia Borane

In this study, polypyrrole (PPy) nanofibers were used to synthesize a super-activated carbon material. A highly-dispersed Co-Ni-B catalyst was supported on PPy nanofiber-derived activated carbon (PAC) by chemical reduction. The Co-Ni-B/PAC hybrid catalyst exhibited excellent catalytic performance for the decomposition of ammonia borane (AB) in an aqueous alkaline solution at room temperature. The size of the metal particles, morphology of Co-Ni-B/PAC, and catalytic activity of the supported catalyst were investigated. Ni-B, Co-B, and Co-Ni-B catalysts were also synthesized in the absence of PAC under similar conditions for comparison. The maximum hydrogen generation rate (1451.2 mL−1·min−1·g−1 at 25 °C) was obtained with Co-Ni-B/PAC. Kinetic studies indicated that the hydrolysis reaction of AB was first order with respect to Co-Ni-B/PAC, and the activation energy was 30.2 kJ·mol−1. Even after ten recycling experiments, the catalyst showed good stability owing to the synergistic effect of Co-Ni-B and PAC.

Revealing the synergetic effects in Ni nanoparticle-carbon nanotube hybrids by scanning transmission X-ray microscopy and their application in the hydrolysis of ammonia borane.

The hybrids of carbon nanotubes (CNTs) and the supported Ni nanoparticles (NPs) have been studied by scanning transmission X-ray microscopy (STXM) and tested by the hydrolysis reaction of ammonia borane (AB, NH3BH3). Data clearly showed the existence of a strong interaction between Ni NPs and thin CNTs (C-O-Ni bonds), which favored the tunable (buffer) electronic structure of Ni NPs facilitating the catalytic process. The hydrolysis process of AB confirmed the hypothesis that the hybrids with a strong interfacial interaction would show superior catalytic performance, while the hybrids with a weak interfacial interaction show poor performance. Our results provide a wealth of detailed information regarding the electronic structure of the NP-CNT hybrids and provide guidance towards the rational design of high-performance catalysts for energy applications.

Hydrolysis of ammonia–borane catalyzed by an iron–nickel alloy on an SBA-15 support

An unsupported iron–nickel (Fe–Ni) alloy and several Fe–Ni alloy deposited on SBA-15 (Santa Barbara Amorphous-15) supports (Fe–Ni/SBA) with various Fe–Ni contents are prepared and used as catalysts in the hydrolysis of ammonia–borane (AB) for hydrogen generation. By maintaining a constant concentration of Fe–Ni in the AB aqueous solutions, we investigate the influence of the SBA-15 support on the Fe–Ni catalytic activity in the AB hydrolysis reaction. The SBA-15 support helps disperse the Fe–Ni alloy particles on its surface, which consequently improves the catalytic activity of the Fe–Ni. However, the presence of SBA-15 particles in the aqueous solution also retards the migration of the AB molecules in solution toward the Fe–Ni catalysts, increasing the induction time of the AB hydrolysis reaction. Therefore, there is an optimal Fe–Ni content in Fe–Ni/SBA for the catalysis of the AB hydrolysis reaction.

Synthesis of Ni–Ru Alloy Nanoparticles and Their High Catalytic Activity in Dehydrogenation of Ammonia Borane

We report the synthesis and characterization of new Ni(x)Ru(1-x) (x = 0.56-0.74) alloy nanoparticles (NPs) and their catalytic activity for hydrogen release in the ammonia borane hydrolysis process. The alloy NPs were obtained by wet-chemistry method using a rapid lithium triethylborohydride reduction of Ni(2+) and Ru(3+) precursors in oleylamine. The nature of each alloy sample was fully characterized by TEM, XRD, energy dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). We found that the as-prepared Ni-Ru alloy NPs exhibited exceptional catalytic activity for the ammonia borane hydrolysis reaction for hydrogen release. All Ni-Ru alloy NPs, and in particular the Ni(0.74)Ru(0.26) sample, outperform the activity of similar size monometallic Ni and Ru NPs, and even of Ni@Ru core-shell NPs. The hydrolysis activation energy for the Ni(0.74)Ru(0.26) alloy catalyst was measured to be approximately 37 kJ mol(-1). This value is considerably lower than the values measured for monometallic Ni (≈70 kJ mol(-1)) and Ru NPs (≈49 kJ mol(-1)), and for Ni@Ru (≈44 kJ mol(-1)), and is also lower than the values of most noble-metal-containing bimetallic NPs reported in the literature. Thus, a remarkable improvement of catalytic activity of Ru in the dehydrogenation of ammonia borane was obtained by alloying Ru with a Ni, which is a relatively cheap metal.

Bifunctional catalytic/magnetic Ni@Ru core–shell nanoparticles

Core-shell structured Ni@Ru bimetallic nanoparticles are demonstrated as a bifunctional nanoplatform system for the hydrolysis reaction of ammonia-borane and also for magnetic separation.