Catalytic Hydrolysis Of Ammonia Borane Research Articles

PVP-Adjusted Crystal Surfaces of PtPd Nanoparticles for Enhancing the Catalytic Hydrolysis of Ammonia Borane

PVP-Adjusted Crystal Surfaces of PtPd Nanoparticles for Enhancing the Catalytic Hydrolysis of Ammonia Borane

Exploring Enhanced Hydrolytic Dehydrogenation of Ammonia Borane with Porous Graphene-Supported Platinum Catalysts.

Graphene is a good support for immobilizing catalysts, due to its large theoretical specific surface area and high electric conductivity. Solid chemical converted graphene, in a form with multiple layers, decreases the practical specific surface area. Building pores in graphene can increase specific surface area and provide anchor sites for catalysts. In this study, we have prepared porous graphene (PG) via the process of equilibrium precipitation followed by carbothermal reduction of ZnO. During the equilibrium precipitation process, hydrolyzed N,N-dimethylformamide sluggishly generates hydroxyl groups which transform Zn2+ into amorphous ZnO nanodots anchored on reduced graphene oxide. After carbothermal reduction of zinc oxide, micropores are formed in PG. When the Zn2+ feeding amount is 0.12 mmol, the average size of the Pt nanoparticles on PG in the catalyst is 7.25 nm. The resulting Pt/PG exhibited the highest turnover frequency of 511.6 min-1 for ammonia borane hydrolysis, which is 2.43 times that for Pt on graphene without the addition of Zn2+. Therefore, PG treated via equilibrium precipitation and subsequent carbothermal reduction can serve as an effective support for the catalytic hydrolysis of ammonia borane.

RuCo@P Core-Shell Nanoparticles Filled with Carbon Nanotubes for Highly Effective Catalytic Hydrolysis of Ammonia Borane

The doping of nonmetals in multiphase metal catalysts can effectively improve the catalytic performance and reduce the catalyst cost. In this study, we synthesized transition metal phosphide (RuCo@P/CNT) catalysts loaded on carbon nanotubes (CNT) using sodium borohydride (NaBH4) as the reducing agent. The microstructure and phase composition of RuCo@P/CNT nanoparticles were investigated using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), transmission electron microscopy (TEM), and BET. RuCo@P/CNT nanoparticles show superior catalytic activity and cycle stability in the catalytic ammonia borane hydrolysis process compared to Ru/CNT and RuCo/CNT nanoparticles, retaining 65.74% of their initial catalytic activity after 5 reaction cycles. The test yielded values for turnover frequency and activation energy of 327.33 min-1 and 36.77 kJ·mol-1, respectively. Additionally, a kinetic isotope effect value of 2.61 for H2O/D2O showed that O-H bond breaking in proportional acceptor water is the decisive step in the dehydrogenation of ammonia borane, and based on this discovery, a specific mechanism for the catalytic hydrolysis of AB by RuCo@P NPs is postulated.

Water State-Driven Catalytic Hydrolysis of Ammonia Borane on Cu3P-Carbon Dot-Cu Composite.

Hydrogen production from ammonia borane (AB) is usually governed by water activation, which is not only energy-intensive but also requires expensive and complicated catalysts. We here propose an integrated photocatalytic-photothermal system that dramatically improves water activation and lowers the transport resistance of H2 by means of intermediate state water evaporation. This system is constructed by covering nanocomposites (Cu3P-carbon dots-Cu) upon vertically aligned acetate fibers (VAAFs). As a result of superior hydration effect of VAAFs and local photothermal heating for rapid water evaporation, its hydrogen production efficiency from AB hydrolysis reaches over 10 times the particulate suspension system under solar irradiation. Mechanism analysis reveals that the rapid vaporization of intermediate water promotes the cleavages of O-H bonds in bound water and the adsorption reaction of AB and water molecules at active sites. Therefore, this work provides a novel approach to optimize catalytic reaction in thermodynamics and kinetics for the hydrolysis of AB.

Halloysite-based aerogels for efficient encapsulation of phase change materials with excellent solar energy storage and retrieval performance

Developing low-cost composite phase change materials with good shape stability, excellent mechanical strength, high thermal conductivity, large encapsulation ratio, strong light absorption and eminent solar-to-thermal conversion capacity is of great challenge to solve the scaling-up related issues of organic solid–liquid phase change materials during the utilization of solar energy. In this work, halloysite/poly(vinyl alcohol) and halloysite/poly(vinyl alcohol)/reduced graphene oxide aerogels with rich three-dimensional honeycomb structure were prepared by a freezing and freeze-drying method, which can significantly promote the encapsulation ratio of lauric acid in the pores of both aerogels and halloysite nanotube. Halloysite nanotube with high aspect ratio can improve the compressive strength of the aerogels and shape stability of the composite phase change materials, while reduced graphene oxide can reinforce the thermal conductivity and light absorption ability. After encapsulation of lauric acid, the halloysite/poly(vinyl alcohol) 9:1 and halloysite/poly(vinyl alcohol)/reduced graphene oxide 9:1 phase change composites demonstrate extraordinarily high latent heat of 195.4 J/g and 197.0 J/g, respectively, leading to high encapsulation ratios of 97.2 % and 98.1 % respectively, accompanied by good chemical and thermal stability over 300 thermal cycles. The thermal conductivity of lauric acid@halloysite/poly(vinyl alcohol)/reduced graphene oxide is remarkably elevated to 0.343 W/m∙K, exceeding 39.4 % that of pure lauric acid (0.246 W/m∙K). Besides, the lauric acid@halloysite/poly(vinyl alcohol)/reduced graphene oxide realizes a conspicuous solar-to-thermal conversion with solar absorption capacity of 95 % throughout the full spectrum of solar light. The marvelous improvement in the solar-to-thermal conversion efficiency can be attributed to thermally conductive interconnected network of halloysite nanotube and reduced graphene oxide. Thus, lauric acid@halloysite/poly(vinyl alcohol)/reduced graphene oxide and lauric acid@halloysite/poly(vinyl alcohol) are tentatively used in the catalytic hydrolysis of ammonia borane, and they can efficiently harvest, convert and store solar energy in the form of thermal energy and release it for the reaction, which obviously accelerates the extent of reaction with turnover frequency increasing from 29.50 (molH2/molcatalyst·min) at 25 °C to 59.18 and 41.74 (molH2/molcatalyst·min) under the heating of solar energy stored lauric acid@halloysite/poly(vinyl alcohol)/reduced graphene oxide and lauric acid@halloysite/poly(vinyl alcohol), respectively. This work paves a way for fabricating halloysite-based aerogel and composite phase change materials for thermal/solar energy saving application.

Controllable Synthesis of MoC and Mo2C to Boost Hydrogen Generation from Ammonia Borane Hydrolysis

Ammonia borane has been proposed as a competitor to boost H2 evolution via the catalytic hydrolysis reaction at mild temperatures. A series of carbon nanotubes (CNTs)-supported Ni–MoxC catalysts with different MoxC crystalline phases are controllably synthesized using a facile two-step impregnation method followed by the thermal treatment. The catalyst structure and physicochemical properties are studied. The incorporation of MoxC is effective for enhancing the catalytic activity of Ni/CNTs, and the β-Mo2C is more beneficial to the ammonia borane hydrolysis than the α-MoC. 10Ni30Mo2C/CNTs exhibit superior catalytic activity with a turnover frequency (TOF) value of 71.0 min–1. Both experimental and theoretical results suggest that MoxC is responsible for H2O adsorption and activation while Ni is contributed to the ammonia borane molecule. Thus, this synergistic effect between MoxC and Ni enhances the catalytic hydrolysis of ammonia borane. This finding demonstrates the huge potential of MoxC for ammonia borane hydrolysis in hydrogen storage applications and provides a fangled sight for developing a unique class of low-cost catalytic system.

Synthesis of rGO supported Cu@FeCo catalyst and catalytic hydrolysis of ammonia borane.

Highly dispersed Cu@FeCo/rGO catalysts have been prepared by two-step reduction method and used for hydrogen production from ammonia borane (NH3BH3, AB) hydrolysis at 298 K. The activity and reusability of synthesized composite catalyst were much more higher than Cu@FeCo for AB hydrolysis dehydrogenation at 298 K. Kinetic study manifested that AB hydrolysis dehydrogenation with Cu@FeCo/rGO catalysts was approaching to the first order at different catalyst concentrations. The hydrolysis reaction completed within four minutes, and its maximum hydrogen production rate reached to 7863.0 ml min-1 g-1 at 298 K.

Coupling ultralow-content ruthenium with nickel hydroxide via corrosion engineering for highly efficient hydrogen generation from ammonia borane

Efficient and controllable release of hydrogen from solid hydrogen storage materials is a promising way to produce hydrogen safely and on-demand. The development of economical, highly active, easily recyclable catalysts is critical for practical applications, which remains a great challenging. Herein, the easily controllable and cost-effective corrosion strategy is ingeniously developed to simply prepare ultralow-content ruthenium coupled with nickel hydroxide on nickel foam (Ru–Ni–NF). After experiencing the spontaneous oxidation-reduction reactions between the reactive NF and Ru3+, ultrafine Ru nanoparticles decorated nickel hydroxide nanosheets are in situ intimately grown on porous NF networks. The optimal Ru–Ni–NF catalyst exhibits the excellent performance for catalytic hydrolysis of ammonia borane with a high turnover frequency (TOF) of 539.6 molH2 molRu−1 min−1 at 298 K and a low apparent activation energy of 36.4 kJ mol−1, due to the synergistic effect between Ru nanoparticles and nickel hydroxide nanosheets. Furthermore, the Ru–Ni–NF catalyst possesses easy separation and outstanding durability, which is superior to powdered catalysts. This study provides a facile and economical strategy for the preparation of ultralow-content noble metal supported metal foam-type catalysts for dehydrogenation of ammonia borane.

Photohydrolysis of Ammonia Borane for Effective H2 Evolution via Hot Electron-Assisted Energy Cascade of Au-WO2.72/TiO2

Catalytic hydrolysis of ammonia borane has drawn much attention for on-board hydrogen generation because of its high hydrogen capacity. Herein, a ternary Au-WO2.72/TiO2 hybrid is synthesized for efficient photohydrolysis of ammonia borane. The Au nanoparticles (NPs) deposited were in situ-reduced by defective WO2.72 nanowires, and 2 wt % Au-WO2.72 is optimal to realize high photoactivity because of the high light absorption and low charge-transfer resistance, which is then combined with TiO2 nanosheets to form a 2%Au-WO2.72/TiO2 hybrid. This hybrid possesses compact interfaces among Au, WO2.72, and TiO2, and the electron pump effect of Au surface plasmon resonances and the electron capture property of TiO2 accelerate the electron transfer from WO2.72 to Au and then to TiO2, leading to the effective separation and long lifetime of photoinduced charges. Therefore, the 2%Au-WO2.72/TiO2 hybrid shows very high catalytic activity under visible light with H2 evolution rates 2.67- and 31-times higher than those for 2%Au-WO2.72 and WO2.72, respectively.

Noble-metal-free CuNi/Co3O4 hybrid nanosheets as efficient and magnetically recyclable catalysts for hydrolysis of ammonia borane

The development of inexpensive and high-performance catalysts is a hot topic in the field of catalytic hydrolysis of ammonia borane (AB). In this work, a series of CuNi bimetallic nanoparticles (NPs) anchored on Co3O4 with magnetic properties was fabricated via impregnation reduction method. Befitting from the synergistic effect between Cu and Ni species and the strong interactions between the bimetallic NPs and the supporting substrate, the as-prepared CuNi/Co3O4 catalyst (with a bimetallic loading weight of 6.2 wt% and the mole ratio of Cu:Ni is 1:1) affords a high hydrogen generation rate of 11,846.9 mL min−1 g−1 with a total turnover frequency (TOF) value of 31.5 molH2 molmetal−1 min−1 0.14 M NaOH medium at 298 K. Besides, this catalyst also exhibits good magnetic separability. These results indicate that cobalt oxide has good application prospects in the field of AB hydrolysis, which may provide a promising lead for the construction of other efficient heterogeneous catalysts for industrial applications in energy and environmental fields.

Regulation of Co3O4/Co hetero-structures embedded in N-doped porous carbon as high-efficient catalysts for dehydrogenation of ammonia borane

Catalytic hydrolysis of ammonia borane (NH3BH3, AB) is a promising way to supply hydrogen for new energy devices. To accommodate the requirement of fast hydrogen-generation, developing high-efficient and economic catalyst is a crucial subject. In this work, Co3O4/Co hetero-structures embedded in N-doped porous carbon (Co3O4/Co@NC) were prepared as highly efficient catalysts for hydrolysis of AB by a two-step pyrolysis-oxidation method using ZIF-67 as precursor. It is found that the interfacial interaction between Co3O4 and Co nanoparticles plays a crucial role in the facilitation of the dehydrogenation of AB from hydrolysis, and the composition of Co3O4/Co hetero-structures can be regulated via controlling the first-step pyrolysis temperature. As a result, Co3O4/Co@NC-800 with optimized composition and high porosity, exhibits excellent catalytic activity with a turnover frequency (TOF) of 40.6 molH2·min−1·molCo−1, and high stability. This work provides a new understanding for the design and fabrication of high-efficient and economical nanocatalysts for AB hydrolysis.

Visible-light-enhanced hydrogen evolution from catalytic hydrolysis of ammonia borane using Ru nanoparticles supported on CdS-modified graphitic carbon nitride

A high-efficiency composite photocatalyst, Ru/CdS/C3N4, was successfully synthesized for hydrogen generation from the hydrolysis of ammonia borane under visible-light irradiation.

Synergistic catalytic hydrolysis of ammonia borane to release hydrogen over AgCo@CN

Synergistic catalytic AB hydrolysis to generate hydrogen was achieved over AgCo@CN synthesized by auto-reduction between Co@CN and a Ag precursor.

Synthesis of Metal Nanoparticles Supported on Carbon Nanotube with Doped Co and N Atoms and its Catalytic Applications in Hydrogen Production.

A method for facile synthesis of nanostructured catalysts supported on carbon nanotubes with atomically dispersed cobalt and nitrogen dopant is presented herein. The novel strategy is based on a facile one-pot pyrolysis treatment of cobalt (II) acetylacetonate and nitrogen-rich organic precursors under Ar atmosphere at 800 °C, resulting in the formation of Co- and N- co-doped carbon nanotube with earthworm-like morphology. The obtained catalyst was found to have a high density of defect sites, as confirmed by Raman spectroscopy. Here, cobalt (II) nanoparticles were stabilized on the atomically dispersed cobalt- and nitrogen-doped carbon nanotubes. The catalyst was confirmed to be effective in the catalytic hydrolysis of ammonia borane, in which the turnover frequency was 5.87 mol H2·molCo-1·min-1, and the specific hydrogen generation rate was determined to be 2447 mL H2·gCo-1·min-1. A synergistic function between the Co nanoparticle and the doped carbon nanotubes was proposed for the first time in the catalytic hydrolysis of ammonia borane reaction under a mild condition. The resulting hydrogen production with its high energy density and minimal refueling time could be suitable for future development as energy sources for mobile and stationary applications such as road trucks and forklifts in transport and logistics.

Maximizing Metal-Support Interactions in Pt/Co3O4 Nanocages to Simultaneously Boost Hydrogen Production Activity and Durability.

Catalytic hydrolysis of ammonia borane (AB) provides an effective way to generate pure H2 at ambient temperature for fuel cells. Pt-based catalysts usually exhibit great initial activity toward this reaction but deactivate quickly. Here, we report that the metal-support interactions in Pt/Co3O4 nanocages can simultaneously accelerate the H2 generation and enhance the catalyst's stability. The Pt/Co3O4 catalyst is made for the first time by embedding Pt clusters (∼1.2 nm) in a high-surface-area Co3O4 nanocage to maximize the metal-support interface. The turnover frequency of the Pt/Co3O4 catalyst is about nine times higher than that of commercial Pt/C and outperforms almost all other Pt-based catalysts. X-ray absorption spectroscopy, X-ray photoelectron spectroscopy, in situ spectroscopy, and density functional theory calculations suggest that the Co3O4 nanocages with rich oxygen vacancies facilitate the adsorption and dissociation of H2O to give electropositive H (Hδ+), while the in situ embedded Pt clusters can accelerate the formation of electronegative H (Hδ-) from AB. Subsequently, the Hδ+ and Hδ- spill over to the abundant interfacial sites and bond into H2. In addition to this dual-function synergy effect, the strong metal-support electronic interactions between Co3O4 and Pt benefit the desorption of poisonous B-containing byproducts from Pt sites. This effect together with cluster anchoring leads to a fivefold enhancement in durability compared to commercial Pt/C. The metal-support interactions revealed in this study provide more options for catalyst design toward facile H2 production from chemical hydrogen storage materials.

Binary CuO/TiO2 nanocomposites as high-performance catalysts for tandem hydrogenation of nitroaromatics

In situ hydrogenation of unsaturated compounds by released hydrogen from various hydrogen sources is a good strategy to achieve highly selective hydrogenation. In this work, inexpensive CuO/TiO 2 nanocomposites were systematically screened their performance for catalyzing dehydrogenation of ammonia borane (AB) and the tandem hydrogenation of some nitroaromatics. Those CuO/TiO 2 binary nanocomposites were found to maximize the hydrogen production from the catalytic hydrolysis of AB. Owing to a positive in-situ hydrogen activation, under mild conditions these CuO/TiO 2 nanocomposites exhibited highly excellent reactivities accompanying with better recyclability in the current one-pot hydrogenation. Notably, a selected CuO (0.5) /TiO 2(0.5) nanocomposites displayed high activity and regioselectivity (up to100% yield of aim product) as well as increased ability of inhibiting the dehalogenation reaction, especially for 4-bromonitrobenzene or 4-iodonitrobenzene (up to 71.65% yield for 4-bromoaniline or 68.02% yield of 4-iodoaniline). Moreover, that CuO (0.5) /TiO 2(0.5) nanocomposites from a co-precipitation method displayed relatively better recyclability against those two control samples obtained from a stepwise preparation process. Owing to positive in-situ hydrogen activation mechanism, CuO/TiO 2 binary nanocomposites from co-precipitation method display highly excellent reactivity, regioselectivity, and better recyclability for the tandem hydrogenation of aromatic nitro-compounds under highly mild conditions. • Binary CuO/TiO2 nanocomposites exhibited attractive reactivity toward the tandem hydrogenation of nitro-compounds. • Control experiments powerfully confirm a positive in-situ hydrogen activation benefitting the efficient tandem hydrogenation. • Distinguishable catalytic performances were observed for those catalysts coming from different preparation methods.

Ultrafast, dry microwave-assisted surface property modulations to boost carbon stabilized Ru nanocatalyst for catalytic hydrogen evolution

Developing a facile, ultrafast, and solid-state strategy to modulate the surface chemistry and textural properties of carbon materials and thereby tune the surface sites of metal nanoparticles (NPs) anchored on themselves is one of the most challenging work. Herein, we develop a simple, rapid but efficient microwave-assisted solid-state strategy to modify carbon black (CB) with rich oxygenated groups, defects, and tunable textural properties. The simple and ultrafast treatment in a household microwave oven for only 10 s not only introduces abundant oxygenated groups and defects but also considerably adjusts the textural properties of OCB, which are beneficial for obtaining uniformly dispersed Ru nanoclusters (2.0 nm in diameter). The achieved Ru/OCB reveals a considerable activity improvement in catalytic hydrolysis of ammonia borane (AB) with turnover frequencies of 602 min−1 in aqueous solution and 1240 min−1 in alkaline solution, surpassing the Ru/CB and many reported Ru-based catalysts. Kinetic isotope effect measurement indicates that the activation of O–H bond in H2O is the rate-determining step toward AB hydrolysis. This study offers an ultrafast but efficient strategy to modify carbon materials as catalyst supports.

One-pot co-reduction synthesis of orange-like Pd@Co@P nanoparticles supported on rGO for catalytic hydrolysis of ammonia borane

Transition metal phosphide based orange-like Pd@Co@P nanoparticles supported on reduced graphene oxide (Pd@Co@P/rGO) have been synthesized by a one-pot co-reduction at room temperature using methylamine borane (MeAB) as the reducing agent. The prepared Pd@Co@P/rGO nanoparticles were characterized by powder X-ray diffraction (XRD), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), selected area electron diffraction (SAED) and confocal Raman microscopy (Raman). Compared with Pd/rGO and Pd@Co/rGO, the Pd@Co@P/rGO catalyst has higher catalytic activity for the hydrolytic production of ammonia borane (AB) with the turnover frequency value (TOF) of 127.57 min−1 and the activation energy of 39.05 kJ mol−1. This excellent catalytic performance may be caused by the orange-like structure and good dispersion of Pd@Co@P/rGO nanoparticles, and the synergistic electron interactions between palladium, cobalt, and phosphorus.

Recent Advances in Hydrogen Generation by Catalytic Hydrolysis of Ammonia Borane

Recent Advances in Hydrogen Generation by Catalytic Hydrolysis of Ammonia Borane

Experimental and DFT studies on Hexacoordinated acyl(alkyl)and Pentacooordinated Hydroxyalkyl(phosphinite)erhodium(III). Catalytic Hydrolysis of Ammonia Borane

Abstract[Rh(nbd)Cl]2 (nbd=norbornadiene) reacts with quinoline‐8‐carbaldehyde (C9H6NCHO) and pyrazole (Hpz) affording, depending on Rh/Hpz ratio, acyl‐alkyl [Rh(μ‐Cl)(C9H6NCO)(Hpz)(σ‐C7H9)]2 (1) or [RhCl(C9H6NCO)(Hpz)2(σ‐norbornenyl)] (2), stereoselectively as confirmed by DFT calculations. Hydrogen bond between NH‐pyrazole and O‐acyl occurs. 1 and 2 react with diphenylphosphine oxide (SPO) giving 16e [RhCl(C9H6NC(nbyl))(Ph2PO)(Hpz)] (3) through SPO κ1‐P‐coordination, C−C bond coupling between acyl and norbornenyl and outer‐sphere O(P)‐to‐O(C) hydrogen transfer. 3 shows distorted trigonal bipyramidal structure with weak intramolecular (C)−OH⋅⋅⋅O(=P) and NH⋅⋅⋅Cl hydrogen bonds. DFT calculations indicate this 16e structure being favoured by σ‐ and π‐type orbital multi‐overlapping between pyrazole and both the OH⋅⋅⋅O and chlorine and by intermolecular forces in the crystal. Solutions of 3 contain an equilibrium between trigonal bipyramid and a square‐planar pyramid with OH interacting with phosphoryl and NH, confirmed by DFT 13C NMR calculations. 1 is very efficient homogeneous catalyst for H3N−BH3 hydrolysis to release hydrogen under air.