Catalysts For Hydrolysis Of Ammonia Borane Research Articles

Silica Confinement for Stable and Magnetic Co-Cu Alloy Nanoparticles in Nitrogen-Doped Carbon for Enhanced Hydrogen Evolution.

Ammonia borane (AB) with 19.6 wt % H2 content is widely considered a safe and efficient medium for H2 storage and release. Co-based nanocatalysts present strong contenders for replacing precious metal-based catalysts in AB hydrolysis due to their high activity and cost-effectiveness. However, precisely adjusting the active centers and surface properties of Co-based nanomaterials to enhance their activity, as well as suppressing the migration and loss of metal atoms to improve their stability, presents many challenges. In this study, mesoporous-silica-confined bimetallic Co-Cu nanoparticles embedded in nitrogen-doped carbon (CoxCu1-x@NC@mSiO2) were synthesized using a facile mSiO2-confined thermal pyrolysis strategy. The obtained product, an optimized Co0.8Cu0.2@NC@mSiO2 catalyst, exhibits enhanced performance with a turnover frequency of 240.9 molH2 ⋅ molmetal ⋅ min-1 for AB hydrolysis at 298 K, surpassing most noble-metal-free catalysts. Moreover, Co0.8Cu0.2@NC@mSiO2 demonstrates magnetic recyclability and extraordinary stability, with a negligible decline of only 0.8 % over 30 cycles of use. This enhanced performance was attributed to the synergistic effect between Co and Cu, as well as silica confinement. This work proposes a promising method for constructing noble-metal-free catalysts for AB hydrolysis.

Ruthenium nanoparticles supported on functionalized carbon nanotubes as high-efficiency catalysts for ammonia borane hydrolysis

Developing high-activity catalysts for the hydrolysis of ammonia borane (NH3BH3; AB) is a crucial and urgent task, which is presently considered an effective strategy for hydrogen generation in the applications of portable proton exchange membrane fuel cells (PEMFCs). In this study, carbon nanotubes (CNTs) were modified by self-growth of metal-organic frameworks (MOFs) on their surfaces. As self-sacrificial templates, the carbonization of cobalt and nitrogen containing MOFs led to the modification of CNT. Subsequently, cobalt was transformed into cobalt phosphide (Co2P) via phosphatization to form Co2P/N co-decorated CNTs (NCP-CNTs). Ru/NCP-CNT catalysts were obtained by loading ruthenium nanoparticles (NPs) using a chemical reduction method and their catalytic performance for H2 production via the hydrolysis of AB was systematically investigated. Ru/NCP-CNTs exhibited excellent catalytic activity, with an initial high turnover frequency (TOF) of 193.9 molH2·molRu−1·min−1 and a low activation energy of 32.4 kJ·mol−1. The incorporation of Ru NPs and their excellent synergistic effect with the NCP-CNT supports can explain the improved performance. This work provides an updated approach for fabricating low-cost and high-efficiency catalysts for the hydrolysis of AB.

Engineering a hollow bowl-like porous carbon-confined Ru-MgO hetero-structured nanopair as a high-performance catalyst for ammonia borane hydrolysis.

Exploration of high-performance catalysts holds great importance for on-demand H2 production from ammonia borane (AB) hydrolysis. In this work, a hollow bowl-like porous carbon-anchored Ru-MgO hetero-structured nano-pair with high-intensity interfaces is made, using a tailored design approach. Consequently, the optimized catalyst shows AB hydrolysis activity with a turnover frequency value of 784 min-1 in aqueous media and 1971 min-1 in alkaline solvent. Robust durability is also achieved, with slight deactivation after a ten-cycle test. Combined experimental and theoretical calculations validate the positive function of the interface between Ru and MgO for facilitating H transfer and boosting water activation, thus leading to improved AB hydrolysis performance. This study could be valuable in guiding the upgradation of Ru catalytic systems, to advance their practical applications.

Oxygen vacancies and morphology engineered Co3O4 anchored Ru nanoparticles as efficient catalysts for ammonia borane hydrolysis

Developing efficient but facile strategies to modulate the catalytic activity of Ru deposited on metal oxides is of broad interest but remains challenging. Herein, we report the oxygen vacancies and morphological modulation of vacancy-rich Co3O4 stabilized Ru nanoparticles (NPs) (Ru/VO-Co3O4) to boost the catalytic activity and durability for hydrogen production from the hydrolysis of ammonia borane (AB). The well-defined and small-sized Ru NPs and VO-Co3O4 induced morphology transformation via in situ driving VO-Co3O4 to 2D nanosheets with abundant oxygen vacancies or Co2+ species considerably promote the catalytic activity and durability toward hydrogen evolution from AB hydrolysis. Specifically, the Ru/VO-Co3O4 pre-catalyst exhibits an excellent catalytic activity with a high turnover frequency of 2114 min−1 at 298 K. Meanwhile, the catalyst also shows a high durability toward AB hydrolysis with six successive cycles. This work establishes a facile but efficient strategy to construct high-performance catalysts for AB hydrolysis.

Ru Nanoparticles Immobilized on Chitosan as Effective Catalysts for Boosting NH3BH3 Hydrolysis

AbstractDeveloping an advanced heterogeneous catalyst is essential for realizing high‐performance ammonia borane (AB) hydrolysis, which is a safe and efficient way to generate hydrogen. In this work, a series of ruthenium (Ru) nanoparticles (NPs) immobilized on chitosan (CS) natural polymers are synthesized via an adsorption‐in situ reduction method. Various analytical techniques, including XRD, XPS, FT‐IR, SEM and TEM, are adopted to explore the structure‐catalytic performance relationships of the obtained catalysts for hydrolysis of AB. Benefitting from the possible interaction between Ru NPs and the amino and hydroxyl groups in CS, the as‐prepared catalysts exhibit excellent catalytic behavior for hydrogen generation from AB hydrolysis. Catalyzed by the optimal Ru/CS, the turnover frequency reaches up to 331.8 min−1 in NaOH solution at 303 K, and the corresponding apparent activation energy is 41.3 kJ mol−1, which are superior to many results previously reported. This work demonstrates that the obtained Ru/CS is a promising and efficient catalyst for the hydrolysis of solid hydrogen storage materials.

PVP-stabilized platinum nanoparticles supported on modified silica spheres as efficient catalysts for hydrogen generation from hydrolysis of ammonia borane

Ammonia borane (AB) is considered to be a promising solid hydrogen carrier. In this work, poly(N-vinyl-2-pyrrolidone) (PVP)-protected platinum nanoparticles are supported on γ-methacryloxypropyltrimethoxysilane (γ-MPS) modified silica spheres (Pt-PVP/SiO2(M)), which are firstly used as highly efficient catalysts for hydrolysis of AB. Platinum nanoparticles possess a tiny size of 2–3 nm and are uniformly dispersed over modified silica spheres. Pt-PVP/SiO2(M) catalysts with a Pt loading amount of 1.30 wt% show the highest catalytic activity with a turnover frequency (TOF) value of 371 molH2 molPt−1 min−1 (866 molH2 molPt−1 min−1 corrected for the surface atoms) at 25 °C. The activation energy is calculated to be 46.2 kJ/mol. Furthermore, owing to the synergistic effect between the modifier of silica spheres and the capping agent of metal nanoparticles, Pt-PVP/SiO2(M) catalysts have a higher loading amount (8.7 and 6.5 times) and TOF value (4.8 and 5.5 times) than the counterparts prepared without γ-MPS and PVP, respectively.

Hexagonal boron nitride supported ruthenium nanoparticles as highly active catalysts for ammonia borane hydrolysis

Ammonia borane (AB) hydrolysis is a comparative strategy for developing the sustainable hydrogen economy. Considering the hydrolysis cannot occur kinetically at low temperature, a suitable catalyst is indispensable. In this work, the dispersed ruthenium nanoparticles are stabilized on hexagonal boron nitride (h-BN) via an adsorption-in situ reduction procedure. Various characterization techniques are adopted for elucidating the structure-performance relationship of the obtained catalysts for the hydrolytic dehydrogenation of AB. In the presence of the resultant Ru/h-BN catalysts, the corresponding turnover frequency (1177.5 min−1) in alkaline solution at 303 K and the apparent activation energy (24.1 kJ mol−1) are superior to most literature previously reported. Our work provides a facile fabrication method for metal-based catalysts, which are highly promising in chemical storage material hydrolysis.

Synthesis of rattle-structured CuCo2O4 nanospheres with tunable sizes based on heterogeneous contraction and their ultrahigh performance toward ammonia borane hydrolysis

Micro/nano-materials with rattle-type structures are attractive because of their unique physicochemical properties and extensive applications. In this study, well-defined rattle-type CuCo2O4 nanospheres were fabricated by heterogeneous contraction caused by non-equilibrium heat treatment with the assistance of an RF (resorcinol formaldehyde) resin colloidal sphere hard template. The sizes of CuCo2O4 nanospheres could be tuned by varying the amount of NH3·H2O used during template synthesis. The possible formation mechanism of rattle-type CuCo2O4 nanospheres was also proposed. When used in ammonia borane hydrolysis, rattle-type CuCo2O4 nanospheres exhibited ultrahigh activity with a turnover frequency of 104.0 min−1, which is one of the highest activities of non-noble-metal based catalysts, and is even higher than many noble-metal-based catalysts. This research provides valuable insights into the development of robust catalysts for ammonia borane hydrolysis. In addition, the synthetic method presented in this work can be easily extended to prepare other oxide composites with rattle structures.

Hierarchical porous CuNi-based bimetal-organic frameworks as efficient catalysts for ammonia borane hydrolysis

Ammonia borane (NH3BH3, AB) hydrolysis is an effective strategy to utilize hydrogen energy. In this work, the hierarchical porous CuNi bimetal-organic frameworks (CuNi-MOFs) are fabricated through a facile solvothermal method and characterized by various techniques. The CuNi-MOFs display outstanding catalytic activity and remarkable durability for the hydrolytic dehydrogenation of AB. The corresponding turnover frequency reaches 40.85 molH2 · molMetal−1 · min−1 and the apparent activation energy (28.99 kJ mol−1) is lower than those of many catalysts previously reported. The results verify the resultant CuNi-MOFs are promising for the hydrolysis of hydrogen storage materials.

Ultrafine Ru nanoparticles anchored to porous g-C3N4 as efficient catalysts for ammonia borane hydrolysis

Hierarchical porous g-C3N4 nanosheets are prepared from melamine using NH4Cl as dynamic gas templates to anchor the ultrafine Ru nanoparticles (NPs) with a facile adsorption-in situ reduction strategy. The results reveal that 1: 3 is the optimal mass ratio for melamine to NH4Cl and the Ru NPs are evenly dispersed in the porous network of g-C3N4 in the corresponding catalysts. Remarkably, the porous catalysts exhibit superior catalytic activity and satisfactory recyclability for ammonia borane (NH3-BH3, AB) hydrolysis. The corresponding turnover frequency is as high as 122.2 × 103 mLH2·gRu-1·min-1 and the apparent activation energy (35.6 kJ mol−1) is competitive. AB hydrolysis is of 1.17-order and near zero-order with respect to the Ru and AB concentrations, respectively. The results demonstrate that the Ru/g-C3N4 catalysts are promising in developing an alternative clean and environmentally friendly energy carrier from the hydrogen storage materials.

CuO–NiO/Co3O4 hybrid nanoplates as highly active catalyst for ammonia borane hydrolysis

Dehydrogenation of hydrogen-rich chemicals, such as ammonia borane (AB), is a promising way to produce hydrogen for mobile fuel cell power systems. However, the practical application has been impeded due to the high cost and scarcity of the catalysts. Herein, a low-cost and high-performing core-shell structured CuO–NiO/Co3O4 hybrid nanoplate catalytic material has been developed for the hydrolysis of AB. The obtained hybrid catalyst exhibits a high catalytic activity towards the hydrolysis of AB with a turnover frequency (TOF) of 79.1 molH2 mol cat−1 min−1. The apparent activation energy of AB hydrolysis on CuO–NiO/Co3O4 is calculated to be 23.7 kJ.mol−1. The synergistic effect between CuO–NiO and Co3O4 plays an important role in the improvement of the catalytic performance. The development of this high-performing and low-cost CuO–NiO/Co3O4 hybrid catalytic material can make practical applications of AB hydrolysis at large-scale possible.

Interface electron collaborative migration of Co–Co3O4/carbon dots: Boosting the hydrolytic dehydrogenation of ammonia borane

Ammonia borane (AB) is an excellent candidate for the chemical storage of hydrogen. However, its practical utilization for hydrogen production is hindered by the need for expensive noble-metal-based catalysts. Herein, we report Co–Co 3 O 4 nanoparticles (NPs) facilely deposited on carbon dots (CDs) as a highly efficient, robust, and noble-metal-free catalyst for the hydrolysis of AB. The incorporation of the multi-interfaces between Co, Co 3 O 4 NPs, and CDs endows this hybrid material with excellent catalytic activity ( r B = 6816 m L H 2 min –1 g Co –1 ) exceeding that of previous non-noble-metal NP systems and even that of some noble-metal NP systems. A further mechanistic study suggests that these interfacial interactions can affect the electronic structures of interfacial atoms and provide abundant adsorption sites for AB and water molecules, resulting in a low energy barrier for the activation of reactive molecules and thus substantial improvement of the catalytic rate. The Co–Co 3 O 4 /CDs was proved to be a highly efficient noble-metal-free catalyst for AB hydrolysis. The incorporation of the multi-interfaces between Co, Co 3 O 4 NPs, and CDs endows the hybrid material with excellent catalytic activity.

Pd nanoparticles anchoring to core-shell Fe3O4@SiO2-porous carbon catalysts for ammonia borane hydrolysis

A modified Stöber method is applied to synthesize the magnetic core-shell Fe3O4@SiO2 particles, followed by compositing a series of porous glucose-derived carbon with ZnCl2 as etchant. Then, ultrafine Pd nanoparticles (NPs) are successfully anchored to the resulting Fe3O4@SiO2-PC composites with an in-situ reduction strategy. The particle sizes of Pd NPs are mainly centered in the range of 2.3–4.3 nm in the as-prepared Pd/Fe3O4@SiO2-PC catalysts, owning a hierarchical porous structure with high specific surface area (SBET = 626.0 m2 g−1) and large pore volume (Vp = 0.61 cm3 g−1). Their catalytic behavior for the hydrogen generation from ammonia borane (AB) hydrolysis is investigated in details. The corresponding apparent activation energy is as low as 28.4 kJ mol−1 and the reaction orders with AB and Pd concentrations are near zero and 1.10 under the present conditions, respectively. In addition, the magnetic catalysts, which could be easily separated out by a magnet, are still highly active even after nine runs, revealing their excellent reusability.

Co3O4/CuMoO4 Hybrid Microflowers Composed of Nanorods with Rich Particle Boundaries as a Highly Active Catalyst for Ammonia Borane Hydrolysis

Dehydrogenation of ammonia borane (AB) is a promising approach for the production and use of hydrogen for industrial and fuel cell applications. The development of low-cost and highly active cataly...

Boron nitride supported NiCoP nanoparticles as noble metal-free catalyst for highly efficient hydrogen generation from ammonia borane

Herein, ternary metal phosphides NiCoP nanoparticles supported on porous hexagonal boron nitride (h-BN) was fabricated via hydrothermal-phosphorization strategy. The as-prepared Ni0.8Co1.2P@h-BN exhibited excellent catalytic performance for the hydrogen generation from ammonia borane (AB) hydrolysis, with an initial turnover frequency of 86.5 mol(H2) mol(Ni0.8Co1.2P) −1 min−1 at 298 K. The experimental outcome can be attributed to the synergistic effect between Ni, Co and P, as well as the strong metal-support interaction between NiCoP and h-BN. This study presents a new paradigm for supporting transition metal phosphides, and provides a new avenue to develop high performance and low cost non noble metal catalysts for hydrolysis of AB.

FeCo alloy encapsulated within carbon nanotube as efficient and stable catalyst for ammonia borane hydrolysis

Herein, commercial dicyandiamide was used as the pyrolysis precursor of carbon nanotubes. Co(NO3)2·6H2O and FeCl3 as non-precious metal precursors were mixed with dicyandiamide to in situ synthesize nitrogenated carbon nanotubes encapsulating Fe and Co nanoparticles via calcination under nitrogen atmosphere. The ratio of different metal species and thus the structure and properties of the final products were investigated in detail. As a result, the Fe0.4Co0.6-NCNTs exhibited optimal catalytic ammonia borane(AB) dyhydrogenation activity with the responding activation energy (Ea) calculated to be 19.89 KJ mol−1, and the TOF value calculated based on metals was 102 molH2 min−1 molcat−1, superior to most well-developed bimetal-based catalysts reported previously. The present method provides cost-effective, high efficiency, and stable materials in developing the sustainable energy conversion systems.

Graphitic carbon nitride‐chitosan composites–anchored palladium nanoparticles as high‐performance catalyst for ammonia borane hydrolysis

Graphitic carbon nitride‐chitosan composites–anchored palladium nanoparticles as high‐performance catalyst for ammonia borane hydrolysis

Ultrafine and highly dispersed Ru nanoparticles supported on nitrogen-doped carbon nanosheets: Efficient catalysts for ammonia borane hydrolysis

Ultrafine monodisperse Ru nanoparticles were synthesized by a facile strategy with nitrogen-doped porous hierarchically porous carbon material (HPCM) as support. The as-synthesized Ru nanoparticles with an average particle size of 1.41 nm were dispersed uniformly on the HPCM surface (Ru/HPCM). The Ru/HPCM catalyst exhibited a high turnover frequency of 440 min−1 and could be reused for eight times in hydrogen generation from ammonia borane hydrolysis. The enhanced catalytic activity of Ru/HPCM could be attributed to the numerous active surface areas provided by ultrafine monodisperse Ru nanoparticles for the reaction. The confinement space of the support and the abundant surface functional groups increased the stability and reusability of the Ru/HPCM catalyst. This facile strategy for synthesis of ultrafine monodisperse metal nanoparticles with high catalytic activity and reusability shows potential for practical applications.

Metal Ruthenate Perovskites as Heterogeneous Catalysts for the Hydrolysis of Ammonia Borane.

Ammonia borane (NH3-BH3) is of interest as a hydrogen storage material because of its ease of use and its ability to release three molar equivalents of H2(g) via catalytic hydrolysis. Most heterogeneous catalysts for ammonia borane hydrolysis are nanoparticles containing expensive noble metals. Here, we show that metal ruthenate perovskites function as active and durable catalysts for ammonia borane hydrolysis. As a bulk powder, CaRuO3 catalyzes the hydrolysis of ammonia borane at room temperature and is recyclable and reusable. CaRuO3 facilitates the release of H2(g) from aqueous ammonia borane solutions at comparable rates to some other heterogeneous catalyst systems while having a low noble metal content. Other ruthenium-based perovskites, including SrRuO3, Ca2LaRuO6, Sr2CoRuO6, and SrLaCoRuO6, are similarly active catalysts for room-temperature ammonia borane hydrolysis.

Ruthenium(0) nanoparticles supported on magnetic silica coated cobalt ferrite: Reusable catalyst in hydrogen generation from the hydrolysis of ammonia-borane

Ruthenium(0) nanoparticles supported on magnetic silica-coated cobalt ferrite (Ru(0)/SiO2-CoFe2O4) were in situ generated from the reduction of Ru3+/SiO2-CoFe2O4 during the catalytic hydrolysis of ammonia-borane (AB). Ruthenium(III) ions were impregnated on SiO2-CoFe2O4 from the aqueous solution of ruthenium(III) chloride and then reduced by AB at room temperature yielding Ru(0)/SiO2-CoFe2O4 which were isolated from the reaction solution by using a permanent magnet and characterized by ICP-OES, XRD, TEM, TEM-EDX and XPS techniques. The resulting magnetically isolable Ru(0)/SiO2-CoFe2O4 were found to be highly reusable catalyst in hydrolysis of AB retaining 94% of their initial catalytic activity even after tenth run. Ru(0)/SiO2-CoFe2O4 provide the highest catalytic activity after the tenth use in hydrolysis of AB as compared to the other ruthenium catalysts. The work reported here also includes the formation kinetics of ruthenium(0) nanoparticles. The evaluation of rate constants for the nucleation and autocatalytic surface growth of ruthenium(0) nanoparticles at various temperatures provides the estimation of activation energy for both reactions; Ea=116±7kJ/mol for the nucleation and Ea=51±2kJ/mol for the autocatalytic surface growth of ruthenium(0) nanoparticles. The report also includes the activation energy of the catalytic hydrogen generation from the hydrolysis of AB (Ea=45±2kJ/mol) determined from the evaluation of temperature dependent kinetic data and the effect of catalyst concentration on the rate of hydrolysis of AB.