Chemical Hydrogen Storage Materials Research Articles

Anomalous metastable hcp Ni nanocatalyst induced by non-metal N doping enables promoted ammonia borane dehydrogenation

Developing high-performing non-noble transition metal catalysts for H2 evolution from chemical hydrogen storage materials is of great significance for the hydrogen economy system, yet challenging. Herein, we present for the first time that anomalous metastable hexagonal close-packed Ni nanoparticles induced by heteroatom N doping encapsulated in carbon (N-hcp-Ni/C) can exhibit admirable catalytic performance for ammonia borane (AB) dehydrogenation, prominently outperforming conventional fcc Ni counterpart with similar morphology and favorably presenting the state-of-the-art level. Comprehensive experimental and theoretical studies unravel that unusual hcp phase engineering of Ni together with N doping could induce charge redistribution and modulate electronic structure, thereby facilitating H2O adsorption and expediting H2O dissociation (rate-determining step). As a result, AB dehydrogenation can be substantially boosted with the assistance of N-hcp-Ni/C. Our proposed strategy highlights that unconventional crystal phase engineering coupled with non-metal heteroatom doping is a promising avenue to construct advanced transition metal catalysts for future renewable energy technologies.

In situ encapsulating cobalt phosphide into a quasi-MOF: a high-performance catalyst for hydrolytic dehydrogenation of ammonia borane

The development of efficient, durable and economical catalysts based on non-precious metals for the controllable and fast hydrogen evolution from chemical hydrogen storage materials is highly desirable for the hydrogen economy.

Cation/anion-doping induced electronic structure regulation strategy to boost the catalytic hydrogen evolution from ammonia borane hydrolysis

Exploration of high-performance and cost-effective catalysts for hydrogen production from chemical hydrogen-storage materials is vital but still a challenge. Herein we report the synthesis of a ZIF-67 derived Co3O4 nanoparticles in a carbon-based nanoframeworks and discover that doping phosphorus into Co3O4 has a unique electronic structure modulation effect, resulting in a nearly 29-fold enhancement of the catalytic activity for ammonia borane hydrolytic dehydrogenation. Furthermore, combining the P doping with Cu doping, a strong synergistic effect is realized to boost the catalytic H2 generation with an astonishing nearly 51-fold improvement (turnover frequency, TOF = 35.6 min−1). Based on the experimental and theoretical results, the enhanced performance is attributed to the optimization of the electronic configuration and the downshift of d-band center over Co3O4 after P/Cu doping, thereby facilitating H2O dissociation and hydrogen desorption. This work will be applicable to designing other metal based nanocatalysts toward more efficient energy conversion reactions.

Carbon supported Pd based catalysts for the hydrolytic dehydrogeneration of morpholine borane

Although the reducing property of morpholine borane is frequently used, there are few studies on its use as a chemical hydrogen storage material. This study presents the catalyst efficiency for hydrogen production in the dehydrogenation reaction of morpholine borane as efficient and cost-effective hydrogen storage material, which can be used as an alternative to depleting fossil fuels. It was studied with four different catalysts as activated Carbon-supported Pd, PdAg, PdNi, and PdCo. Bimetallic palladium based catalysts were used for the dehydrogenation of morpholine borane for the first time. Nanoparticles were synthesized using the chemical reduction method. The catalytic effects of different metal ratios of PdNi/C nanoparticles, which were concluded to have the best catalyst effect, were investigated and it was observed that the ratio of Pd50Ni50/C nanoparticles exhibited better catalytic behavior, and optimization studies were carried out with Pd50Ni50/C nanoparticles. Transmission Electron Microscopy, X-Ray Diffraction, and X-Ray Photoelectron Spectroscopy analyzes were performed for the characterization of nanoparticles. According to the characterization analyzes of Pd50Ni50/C nanoparticles, the mean particle size was determined as 2.0 ± 1.0 nm. Catalyst efficiency was determined by performing the substrate, catalyst, and temperature experiments separately in the dehydrogenation reaction of Morpholine Borane. These parameters are respectively; Ea and ΔH were calculated as 93.2 kJ/mol, and 90.6 kJ/mol. The reusability experiments were carried out in 4 cycles. In other words, with this study, it was concluded that the reusability of Pd50Ni50/C nanoparticles synthesized by the chemical method is high and their catalytic activity is excellent.

Dehydrogenation of hydrous hydrazine over carbon nanosphere- supported PtNi nanoparticles for on-demand H2 release

In despite of significant progresses have been accomplished in the programming and development of updated and efficient nana-catalysts for H2 production from a wide variety of chemical hydrogen storage materials. However, it is a practical matter of the utmost importance to develop the “on-off” control for on demand H2 release in the cause of effectively and safely producing, carrying and depositing H2 gas. Herein, we have first designed and synthesized a sequence of carbon nanosphere (CNS)-stabilized bimetallic PtNi nanoparticles (PtNi/CNS), by stabilization of nearly monodispersed PtNi bimetallic nanoparticles onto the surface of carbon nanosphere, for the highly selective and efficient on-demand H2 release upon the dehydrogenation of hydrous hydrazine. Then, the optional nanocatalyst Pt1Ni1/CNS exhibits the highest catalytic performance in hydrogen production from dehydrogenation of hydrous hydrazine, with 100 % H2 selectivity and the turnover frequency (TOF) of 3928 mol (H2)·molcat−1·h−1 at 50 °C. The detailed physical characterizations have confirmed that the superior catalytic performance of Pt1Ni1/CNS in the H2 release upon hydrous hydrazine dehydrogenation is attributed to the electronic interaction and synergistic effect between Ni and Pt. More importantly, the highly selective “on-off” control for demand-based H2 release upon the dehydrogenation of hydrous hydrazine is successfully realized by pH regulation.

New Liquid Chemical Hydrogen Storage Technology

The liquid chemical hydrogen storage technology has great potentials for high-density hydrogen storage and transportation at ambient temperature and pressure. However, its commercial applications highly rely on the high-performance heterogeneous dehydrogenation catalysts, owing to the dehydrogenation difficulty of chemical hydrogen storage materials. In recent years, the chemists and materials scientists found that the supported metal nanoparticles (MNPs) can exhibit high catalytic activity, selectivity, and stability for the dehydrogenation of chemical hydrogen storage materials, which will clear the way for the commercial application of liquid chemical hydrogen storage technology. This review has summarized the recent important research progress in the MNP-catalyzed liquid chemical hydrogen storage technology, including formic acid dehydrogenation, hydrazine hydrate dehydrogenation and ammonia borane dehydrogenation, discussed the urgent challenges in the key field, and pointed out the future research trends.

Enhanced catalytic behavior of h-BN supported CuNi bimetallic catalysts in hydrolytic dehydrogenation of NH3BH3

The hydrolysis of ammonia borane (NH3BH3, AB) is an efficient strategy for high-purify hydrogen evolution. However, it is indispensable to develop a suitable catalyst because this reaction is kinetically infeasible at room temperature. In this work, we prepared a series of nano hexagonal boron nitride (h-BN) supported CuNi bimetallic catalysts through a facile adsorption-chemical reduction procedure. The effects of various molar ratios of Cu to Ni and CuNi loadings on AB hydrolysis were investigated in details. Benefitting from the proper porous structure, the interesting alloy effect of Cu and Ni, as well as the synergistic effect between h-BN and CuNi, 20 wt% Cu0.5Ni0.5/h-BN displays the highest catalytic activity among the as-prepared catalysts. Apart from satisfactory durability, the corresponding hydrogen generation rate, turnover frequency at 303 K in base solution and apparent activation energy are 2437.0 mL g−1 min−1, 6.33 min−1 and 23.02 kJ mol−1, respectively, which are very outstanding compared with many previous results. Our work not only provides a proper non-precious metal catalyst for hydrogen generation from the hydrolysis of chemical hydrogen storage materials but also offers a facile strategy for synthesizing metallic functional materials.

Methanolysis of ammonia borane using binder‐free hierarchical Co@Ni metal‐organic framework nanocolumn arrays catalyst for hydrogen generation

Ammonia borane (AB) is a potential material for chemical hydrogen storage because of its outstanding stability, high hydrogen density, and the development of highly effective hierarchical catalysts for AB hydrolysis. Herein, the hierarchical Co@Ni metal-organic framework (MOF) nanocolumn arrays (NCAs) on nickel foam (NF) were fabricated through a simple hydrothermal reaction, and the prepared catalysts were characterized using different techniques. The hierarchical Co@Ni-MOFNCA/NF acts as a catalyst for AB methanolysis for hydrogen production. The catalysts exhibited outstanding performance towards AB methanolysis with the TOF of TOF of 20.54 mol H2 mol catalyst−1 min−1. As a result, the activation energy of the Co@Ni-MOF NCA catalyst is 39.72 kJ mol−1 which is compared with some commercial solid support materials such as Al2O3 and AC. Additionally, the effects of nanocatalyst loading and temperatures were studied for the Co@Ni-MOF NCA catalyst. Further, a complete investigation proposes that the outstanding catalytic performance of the Co@Ni-MOF NCA catalyst could be attributed to the synergy between Co and Ni-MOF NCA.

Interfacial ensemble effect of copper nanoparticles and nickel metal-organic framework on promoting hydrogen generation

Ammonia borane is a promising chemical hydrogen storage material to the hydrogen economy in the future. However, efficient and inexpensive catalyst for realizing this process remains challenging. Herein, the interfaces of copper nanoparticles (NPs) and nickel metal-organic framework (MOF) with different Cu/Ni ratios (Cu@Nix-MOF) have been constructed by Cu NPs in situ growth in Ni-MOF via a facile one-step solvothermal method. The Cu@Nix-MOF composites show much higher catalytic activity than their monometal counterparts and the optimized Cu@Ni6-MOF catalyst achieves a turnover frequency of 69.1 min−1 for ammonia borane hydrolysis, superior to most reported Ni-based catalysts. Density functional theory simulation and in situ Raman spectroscopy analysis propose that this remarkable enhanced activity of Ni-based catalysts is induced by a synergetic effect of Cu–Ni2+ dual active sites at their interfaces. This study shows that the strategy of dual active sites hold great promise to achieve efficient non-noble metal catalysts toward heterogeneous catalysis.

Catalytic Effect of Ionic Liquid Induced H2-Release from Morpholine Borane Complex: An Efficient Hydrogen Storage Carrier

The demand for effective and secure chemical hydrogen storage systems impedes hydrogen’s usage as an alternative energy carrier. This work reports the use of morpholine borane (MB) as a novel, efficient, and widely viable chemical hydrogen storage material for mobile applications. Herein, for the first time, hydrogen generation from the thermolytic dehydrogenation of MB in the presence of ionic liquid (IL) media is reported. Initially, the COSMO-SAC model was utilized to determine the most appropriate solvent. [Bmim][HSO4] proved to be an excellent catalytic solvent media with maximum solubility in the morpholine borane complex. Thermal dehydrogenation experiments were conducted separately on solid-state and MB-IL systems at 60 and 80 °C in a vacuum-sealed experimental setup. After a prolonged heating period, the solid-state dehydrogenation of the MB complex released 0.62 equiv of hydrogen, whereas the dehydrogenation of the MB-IL system at 60 and 80 °C released 1.75 and 1.46 equiv of hydrogen in a shorter time. The residue products were characterized using 1H and 11B nuclear magnetic resonance (NMR). 1H NMR validated IL’s activity as a catalytic solvent without affecting its structural identity, whereas 11B NMR helped establish an intra- and intermolecular dehydrogenation mechanism connected with MB. As confirmed by the density functional theory-based transition state calculations, the intramolecular dehydrogenation pathway results in a dehydrocoupled product with minimal energy required for the dehydrogenation reaction.

Cobalt phosphide with porous multishelled hollow structure design realizing promoted ammonia borane dehydrogenation: Elucidating roles of architectural and electronic effect

Exploring advanced non-noble metal-based catalysts for H2 release from chemical hydrogen storage materials is of paramount importance to boost hydrogen economy. Rationally tailoring over architecture and electronic state promises high-efficiency catalysis. Herein we present, for the first time, delicate engineer of cobalt phosphide with a unique porous, multishelled, and hollow architecture (multishelled Co-P) for dramatically promoting ammonia borane (AB) dehydrogenation. Featuring hollow porous structure and complex nanoconfined interior space, multishelled Co-P possesses abundant accessible active sites and facile mass transfer. Importantly, theoretical calculations decipher that P incorporation in Co-P can modulate electronic structure of Co sites to give promoted H2O adsorption and favorable H2O dissociation kinetics (rate-determining step), thereby facilitating AB dehydrogenation. This study provides a fundamental understanding of correlation between electronic state of Co-P and AB dehydrogenation behavior, and highlights that decent architectural engineering coupled with electronic modulation is an effective protocol to construct advanced catalytic systems.

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.

Mechanism of complete dehydrogenation of ammonia borane in electrochemical alkaline environment

Ammonia borane (NH3BH3, AB) has been considered to be a promising chemical hydrogen storage material. The dehydrogenation reaction of AB on the surface of MgSiP2 is investigated by the first-principles method. We have verified the two conventional intramolecular dehydrogenation pathways in the AB hydrolysis reaction, B-distal dehydrogenation (the rate-determining step (RDS) was 0.71 eV) and B-N bond dissociation dehydrogenation (the RDS was 1.00 eV). A new reaction route for dehydrogenation, the BN alternate dehydrogenation, was also explored. The reaction heat of the RDS was 0.71 eV. Note that the entire reaction process in the path of the dissociation of the BN bond can completely release the 6H protons in AB. With the help of the dissociation of H2O, the H2 output ratio of 1:6 can be achieved. In addition, we also considered the influence of *OH– on the RDS of each dehydrogenation reaction in alkaline environment. The calculations have found that the presence of *OH– is beneficial to reduce the reaction heat of dehydrogenation in the AB hydrolysis reaction, making the reaction heat of the RDS of B-distal dehydrogenation is changed from 0.71 eV to 0.15 eV, the B-N bond dissociation dehydrogenation is changed from 1.00 eV to 0.09 eV and the BN alternate dehydrogenation is changed from 0.71 eV to 0.15 eV. This shows that *OH– greatly promotes the production of H2 from the dehydrogenation of AB.

An efficient single atom catalysts Os/P3C sheet for ammonia borane dehydrogenation

Ammonia borane (NH3BH3, AB) has been considered to be a promising chemical hydrogen storage material. Based on density functional theory, a series of transition metal atoms supported P3C (P3C_O) sheet is systematically investigated to screen out the most promising catalyst for dehydrogenation of AB. The results indicate that the Os/P3C and Os/P3C_O could be an efficient single atom catalyst (SACs) and the stepwise reaction pathway with free energy barrier of 2.07 and 1.54 eV respectively. Remarkably, the rate constant further quantitatively confirmed the real situation of the first step of dehydrogenation of AB on the Os/P3C and Os/P3C_O substrates. We found that kf1 at 400 K is equivalent to kf2 at 800 K, which greatly improves the temperature of the first step of AB dehydrogenation on P3C_O. We hope this work can provide a promising method for the design of catalysts for AB dehydrogenation reactions on the surface of two-dimensional materials (2D).

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.

Advances in Catalytic Applications of Zeolite-Supported Metal Catalysts.

Zeolites possessing large specific surface areas, ordered micropores, and adjustable acidity/basicity have emerged as ideal supports to immobilize metal species with small sizes and high dispersities. In recent years, the zeolite-supported metal catalysts have been widely used in diverse catalytic processes, showing excellent activity, superior thermal/hydrothermal stability, and unique shape-selectivity. In this review, a comprehensive summary of the state-of-the-art achievements in catalytic applications of zeolite-supported metal catalysts are presented for important heterogeneous catalytic processes in the last five years, mainly including 1) the hydrogenation reactions (e.g., CO/CO2 hydrogenation, hydrogenation of unsaturated compounds, and hydrogenation of nitrogenous compounds); 2) dehydrogenation reactions (e.g., alkane dehydrogenation and dehydrogenation of chemical hydrogen storage materials); 3) oxidation reactions (e.g., CO oxidation, methane oxidation, and alkene epoxidation); and 4) other reactions (e.g., hydroisomerization reaction and selective catalytic reduction of NOx with ammonia reaction). Finally, some current limitations and future perspectives on the challenge and opportunity for this subject are pointed out. It is believed that this review will inspire more innovative research on the synthesis and catalysis of zeolite-supported metal catalysts and promote their future developments to meet the emerging demands for practical applications.

Remarkably boosting Ru-Ni nanocatalysis via surface/interface regulation for efficient hydrolytic dehydrogenation of ammonia borane

Ammonia borane (NH3BH3, AB) has been considered as one of the most attractive candidates for chemical hydrogen-storage materials. Development of low-cost and high-performance catalysts for hydrogen generation from AB is highly desirable, which is still a huge challenge. Herein, Ru-Ni bimetallic nanoparticles were fabricated on (3-aminopropyl) triethoxysilane-functionalized reduced graphene oxide nanosheet (APTS-rGO) by a facile one-step in situ co-reduction strategy. The newly developed Ru1Ni4/APTS-rGO catalyst with hydrophilic interface and narrow particle size-distribution presented a remarkably enhanced catalytic activity for hydrolytic H2 generation from AB, affording an ultra-high TOF value of 1559 min−1. The APTS-rGO support was effective to minimize the aggregation of Ru-Ni nanoparticles, achieving the immobilization of ultrasmall Ru-Ni nanoparticles (2.0 nm) on support surface. The change in local charge density of catalyst surface caused by Ru-Ni synergistic effect and metals-support interaction improved the catalytic performance of Ru1Ni4/APTS-rGO. Hydrophilic NH2-containing interface ensured high dispersibility of catalysts in reaction solution, increasing the contact opportunities between active sites and AB molecules. These factors contributed together to the exceptional catalytic performance of Ru1Ni4/APTS-rGO. This catalytic system has potential applications in various catalytic fields due to its obvious advantages of the facile preparation method, good hydrophilicity, and the outstanding catalytic performance.

Preparation of graphene-supported Co-CeOx nanocomposites as a catalyst for the hydrolytic dehydrogenation of ammonia borane

Low-cost and high-performance catalyst is crucial for hydrogen generation via the hydrolysis of ammonia borane (NH3BH3, AB) as a chemical hydrogen storage material. In this work, Co-CeOx nanocomposites supported on graphene (Co-CeOx/graphene) were prepared through a facile impregnation and chemical reduction method and used as a catalyst in the hydrolytic dehydrogenation of ammonia borane. The results indicate that the as-prepared Co-CeOx/graphene nanocomposite exhibits superior catalytic activity and recycling stability in the hydrolysis of ammonia borane, owing to the ultra-fine size of Co-CeOx particles, the strong synergistic electronic effect between Co and CeOx, as well as the strong metal-support interaction between Co-CeOx and graphene. For the hydrolysis of ammonia borane over the optimized Co-CeOx/graphene catalyst, the turnover frequency (TOF) reaches 45.1 min−1, with the activation energy (Ea) of 39.5 kJ/mol; such a TOF value is 12 times and 9 times higher than those over Co and Co/graphene, respectively, also much higher than those reported for most noble-metal-free catalysts.

Advances and Prospects in Metal-Organic Frameworks as Key Nexus for Chemocatalytic Hydrogen Production.

Hydrogen is a clean and sustainable energy carrier, which is considered a promising alternative for fossil fuels to solve the global energy crisis and respond to climate change. Social concerns on its safe storage promote continuous exploration of alternatives to traditional storage methods. In this case, chemical hydrogen storage materials initiate plentiful research with special attention to the design of heterogeneous catalysts that can enhance efficient and highly selective hydrogen production. Metal-organic frameworks (MOFs), a kind of unique crystalline porous materials featuring highly ordered porosities and tailorable structures, can provide various active sites (i.e., metal nodes, functional linkers, and defects) for heterogeneous catalysis. Furthermore, the easy construction of active sites in highly ordered MOFs, which can work as plate for the delicate active site engineering, make them ideal candidates for a variety of heterogeneous catalysts including chemocatalytic hydrogen production. This review concentrates on the application of MOFs as heterogeneous catalysts or catalyst supports in chemocatalytic hydrogen production. Recent progresses of MOFs as catalysts for chemocatalytic hydrogen production are comprehensively summarized. The research methods, mechanism analyses, and prospects of MOFs in this field are discussed. The challenges in future industrial applications of MOFs as catalysts for hydrogen production are proposed.

Efficient hydrolytic dehydrogenation of ammonia borane over ultrafine Ru nanoparticles supported on biomass-derived porous carbon

Ammonia borane hydrolysis is a promising strategy for developing sustainable hydrogen energy. However, this reaction is not kinetically feasible at ambient temperature, thus developing a proper catalyst is indispensable. In this work, Porous carbon is facilely prepared from cattail fibers by using K2CO3, and then used to stabilize Ru nanoparticles. The effects of different synthesis parameters for the biomass-derived carbon supports (e. g. K2CO3 dosage and calcination temperature) and various catalytic reaction conditions (e. g. the amounts of the catalysts, ammonia borane and NaOH, and reaction temperature) on the hydrolysis rate of ammonia borane are investigated. Benefitting from the interconnected hierarchical pores of the optimal porous carbon (p-C), which was prepared with a mass ratio of 6 : 1 for K2CO3 to cattail fibers and calcined at 873 K, and the high dispersion of Ru nanoparticles, the optimal Ru/p-C catalysts exhibit excellent catalytic performance. The corresponding apparent activation energy (28.8 kJ mol−1) and turnover frequency (744.7 min−1 in alkaline solution) are superior to many catalysts previously reported. This work offers a competitive catalyst for the hydrolytic dehydrogenation of chemical hydrogen storage materials.