Catalytic Hydrolysis Of Ammonia Borane Research Articles

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.

A comprehensive study on the synthesis, characterization and mathematical modeling of nanostructured Co-based catalysts using different support materials for AB hydrolysis

The present work includes the synthesis of aluminum oxide (Al2O3), multi-walled carbon nanotube (MWCNT), and Eupergit CM-supported Co-based nanoparticles (Co–Fe–B and Co–Mn–B), and the investigation of their hydrolytic efficiency in H2 generation from the catalytic hydrolysis of ammonia borane (NH3BH3). Among the supported catalysts, Co–Fe–B/Eupergit CM exhibited the highest H2 generation rate as 4539 mLmin−1gcatalyst−1 compared to Co–Fe–B/Al2O3 and Co–Fe–B/MWCNT, which exhibited 4373 mLmin−1gcatalyst−1 and 3294 mLmin−1gcatalyst−1, respectively. When Co–Mn–B/ Eupergit CM was used instead of Co–Fe–B/ Eupergit CM, a significant increase in the highest HGR (19.422 mLmin−1gcatalyst−1) was found. Moreover, turnover frequency (TOF) value was calculated as 318 h−1 and 646 h−1 for Co–Fe–B/Eupergit CM and Co–Mn–B/Eupergit CM, respectively.

Ru nanoparticles loaded on tannin immobilized collagen fibers for catalytic hydrolysis of ammonia borane

A kind of Ru-based catalyst was prepared by using a natural polyphenolic polymer (bayberry tannin, BT) immobilized on collagen fiber (CF) as the stabilizer and carrier of Ru nanoparticles (NPs) and characterized to detect its main physicochemical properties. The CF-BT-Ru catalyst was found to be in an orderly fiber morphology with Ru NPs with about diameter of 2.6 nm highly distributed on the surface. The research on catalytic activity of CF-BT-Ru focused on the hydrolysis of ammonia borane (AB) to produce hydrogen. The influences of Ru loading, Ru dosage, AB concentration and temperature on the catalytic AB hydrolysis were investigated in detail, and the related thermodynamic parameters (activation energy (Ea), activation entropy (△S), activation enthalpy (△H) and Gibbs free energy (△G)) were calculated. The experimental results indicated that CF-BT-Ru exhibited high catalytic activity. Its turnover frequency (TOF) was as high as 322 molH2⋅molRu−1⋅min−1 and Ea was as low as 32.41 kJ mol−1 for AB hydrolysis. Moreover, CF-BT-Ru exhibited satisfied reusability and stability. Its activity lost only one-fifth and no obvious agglomeration and leakage of Ru NPs were found after repeated use for 5 times.

Synergistic Catalysis of Binary RuP Nanoclusters on Nitrogen-Functionalized Hollow Mesoporous Carbon in Hydrogen Production from the Hydrolysis of Ammonia Borane.

Exploring highly efficient nanocatalysts for hydrogen (H2) production from catalytic hydrolysis of ammonia borane (AB) under ambient conditions and further unveiling their catalytic mechanism are of critical importance for renewable energy conversion technologies but remain big challenges. Herein, ultrafine binary RuP alloy nanoclusters homogeneously encapsulated onto nitrogen-functionalized hollow mesoporous carbon supports (RuP@NHMCs) are reported as a high-performance platinum (Pt)-free nanocatalyst for catalytic hydrolysis of AB at room temperature. Remarkable catalytic activity with a very high turnover frequency of 1774 molH2 molRu-1 min-1 and a low activation energy of 36.3 kJ mol-1 is observed based on compositional and structural synergies of RuP@NHMCs. Results of control experiments and catalytic kinetics studies reveal that the rate-determining step of catalytic hydrolysis of AB is the oxidation cleavage of a covalently stable H-OH bond, while RuP@NHMCs result in multiple electronic, functional, size, and support effects that kinetically accelerate the cleavage of attacked H-OH. Furthermore, RuP@NHMCs exhibit a good catalytic activity with a high yield of >99% for tandem hydrogenation of nitroarenes coupled with the hydrolysis of AB. We strongly believe that the catalyst design principle reported here could provide a new opportunity for synthesizing other Pt-free high-performance nanocatalysts.

Promoting effect of Co(OH)2 for supported Pt nanocatalysts toward catalytic hydrolysis of ammonia borane

Catalytic hydrolysis of ammonia borane for dehydrogenation is a promising way for generation and storage of hydrogen energy. Catalysts with reduced utilization of costly noble metals while high activity and stability are highly desired. Herein we show that the catalytic activity of the prototypical Pt/SiO2 catalysts towards ammonia borane hydrolysis could be significantly improved by the presence of a layer of Co(OH)2 beneath the supported Pt nanoparticles. By changing the Pt:Co molar ratio in the Pt-Co(OH)2/SiO2 catalysts, the hydrogen generation rates from ammonia borane hydrolysis show a volcano-type curve, with the maximum catalytic activity at the Pt:Co molar ratio of 1:11. The highest turnover frequency value of 829 molH2·molPt−1·min−1 at room temperature outperforms most of the reported Pt-based catalysts, and the apparent activation energy is drastically decreased to 36.2 kJ/mol from 61.6 kJ/mol for Pt/SiO2. The enhanced catalytic performance of Pt-Co(OH)2/SiO2 is attributed to the electrons donation from Co atoms on Co(OH)2 to Pt occurring at the metal-hydroxide interface, which is beneficial for optimizing the oxidation cleavage of the O–H bond of attacked H2O.

Visible-light-enhanced catalytic hydrolysis of ammonia borane using RuP2 quantum dots supported by graphitic carbon nitride

Hydrolytic dehydrogenation of ammonia borane (AB) driven by efficient catalysts has attracted considerable attention and is regarded as a promising strategy for hydrogen generation. Herein, RuP2 quantum dots supported on graphitic carbon nitride (g-C3N4) were successfully prepared by in-situ phosphorization, yielding a highly efficient photocatalyst toward AB hydrolysis. The catalysts were characterized by field-emission scanning electron microscopy, transmission electron microscopy, x-ray diffraction, x-ray photoelectron microscopy, inductively coupled plasma atomic emission spectroscopy, UV–visible diffuse reflectance spectroscopy and photoluminescence spectroscopy. A conventional water-displacement method was employed to record the hydrogen volume as a function of reaction time. Owing to visible-light irradiation, the initial turnover frequency of the AB hydrolysis was significantly enhanced by 110% (i.e., 134 min−1) at room temperature. Furthermore, the apparent activation energy decreased from 67.7 ± 0.9 to 47.6 ± 1.0 kJ mol−1. The photocatalytic hydrolysis mechanism and catalyst reusability were also investigated.

Catalytic Hydrolysis of Ammonia Borane for Hydrogen Production

Catalytic Hydrolysis of Ammonia Borane for Hydrogen Production

Zhao Li

Zhao Li

Syntheses of Pt‐Ni Hollow Nanoalloy for Hydrogen Generation from Catalytic Hydrolysis of Ammonia Borane

AbstractEfficient bimetallic nano‐catalysts consisting of both noble metals and non‐noble metals, are highly desired for the development of new hydrogen storage materials. In this work, supported Pt−Ni nanoalloys with hollow structures were successfully synthesized using galvanic replacement method and exhibited excellent catalytic activity with a turnover frequency as high as 302.3 molH2 ⋅ molmetal−1 ⋅ min−1 for the hydrolysis of ammonia borane. The chemical composition and structure of the alloy can be rationally controlled by the synthetic conditions, which further tune the catalytic activities of hydrogen evolution.

Highly efficient hydrogen evolution from the hydrolysis of ammonia borane solution with the Co–Mo–B/NF nanocatalyst

Catalytic hydrolysis of ammonia borane (NH3BH3) is considered as a secure and effective way to supply hydrogen (H2) source for the proton exchange membrane fuel cell. Hence, cheap and high activity catalysts need to be exploited. In this work, a series of cobalt–molybdenum–boron (Co–Mo–B) composites were successfully supported on the surface of Ni foam (NF in short) via electroless plating method by tuning the depositional pH values. The as-prepared nanocatalysts were marked as Co–Mo–B/NF and characterized using the inductively coupled plasma-mass spectroscopy, scanning electron microscopy, X–ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy technology. These catalysts showed highly efficient catalytic performance for H2 evolution toward the hydrolysis of NH3BH3 solution, and the optimized Co–Mo–B/NF nanocatalyst deposited at pH = 11.5 achieved a higher H2 evolution rate of 6027.1 mL·min−1·g−1 under ambient temperature. The kinetics tests displayed that hydrolysis reaction catalyzed by Co–Mo–B/NF was zero-order in terms of the NH3BH3 concentration, while it was first-order in view of the catalyst concentration. In addition, the activation energy of NH3BH3 hydrolysis was calculated to be 43.6 kJ·mol−1 with the Co–Mo–B/NF nanocatalyst (pH = 11.5), which was lower than that of most of the previous precious metal and non-precious metal catalysts. The corresponding Gibbs free energy of activation was 43.1 kJ·mol−1, meaning that NH3BH3 hydrolysis reaction was non-spontaneous.

Highly Dispersed CuNi Nanoparticles Supported on Reduced Graphene Oxide as Efficient Catalysts for Hydrogen Generation from NH3BH3

Abstract Highly dispersed CuNi nanoparticles (NPs) immobilized on reduced graphene oxide (RGO) were synthesized via the simple in situ co-reduction of an aqueous solution of Copper(II) sulfate pentahydrate, nickel chloride hexahydrate, and graphene oxide (GO) by the reduction of ammonia borane (AB) at room temperature. The powder XRD, FTIR, EDS, and TEM techniques were used to charaterize the structure, size, and composition of the CuNi/RGO catalysts. The as-prepared CuNi/RGO catalysts showed excellent catalytic performance toward the hydrolysis of AB at room temperature. Compared to Cu/RGO, Ni/RGO, and the RGO-free Cu0.6Ni0.4 counterpart, the as-prepared Cu0.6Ni0.4/RGO catalysts showed much better catalytic activity. Furthermore, kinetic studies showed that the catalytic hydrolysis of AB by Cu0.6Ni0.4/RGO has zero order dependence on the AB concentration, but first order dependence on the catalyst concentration. The turnover frequency (TOF) of Cu0.6Ni0.4/RGO catalyst for the hydrolytic dehydrogenation of AB was determined to be about 20.2 mol H2 (mol Cu0.6Ni0.4/RGO)−1 min−1 at 25 °C. In addition, the activation energy (Ea ) of Cu0.6Ni0.4/RGO was determined to be around 17.7 kJ mol−1, which is one of the lowest activation energy’s of the reported metal-based catalysts.

Promoting Effect of Heterostructured NiO/Ni on Pt Nanocatalysts toward Catalytic Hydrolysis of Ammonia Borane.

We report that heterostructured NiO/Ni nanoparticles remarkably promote the catalytic H2 production of platinum (Pt) nanoclusters toward the hydrolysis of ammonia borane (AB). A hybrid nanocatalyst composed ultrasmall Pt nanoclusters, heterostructured NiO/Ni nanoparticles, and a carbon nanotube support (defined as Pt@NiO/Ni-CNT) is fabricated. The resultant Pt@NiO/Ni-CNT is highly efficient for room-temperature H2 production toward catalytic hydrolysis of AB, better than the Pt@NiO-CNT and Pt@Ni-CNT with NiO or Ni alone, and the Pt@NiO/Ni without CNT support. Optimal Pt@NiO/Ni-CNT catalyst exhibits a good catalytic activity with a high TOF of 2665 molH2 molPt-1 min-1 under ambient conditions, overtaking the activities of previously reported catalysts for AB hydrolysis. Catalytic kinetic studies indicate that compositional and structural features of the Pt@NiO/Ni-CNT synergistically accelerate the oxidative clearage of the H-OH bond from attacked H2O (the rate-determining step), thus boosting catalytic hydrolysis of AB kinetically.

Ni0.5Cu0.5Co2O4 Nanocomposites, Morphology, Controlled Synthesis, and Catalytic Performance in the Hydrolysis of Ammonia Borane for Hydrogen Production.

The catalytic hydrolysis of ammonia borane (AB) is a promising route to produce hydrogen for mobile hydrogen‒oxygen fuel cells. In this study, we have successfully synthesized a variety of Ni0.5Cu0.5Co2O4 nanocomposites with different morphology, including nanoplatelets, nanoparticles, and urchin-like microspheres. The catalytic performance of those Ni0.5Cu0.5Co2O4 composites in AB hydrolysis is investigated. The Ni0.5Cu0.5Co2O4 nanoplatelets show the best catalytic performance despite having the smallest specific surface area, with a turnover frequency (TOF) of 80.2 molhydrogen·min−1·mol−1cat. The results reveal that, in contrast to the Ni0.5Cu0.5Co2O4 nanoparticles and microspheres, the Ni0.5Cu0.5Co2O4 nanoplatelets are more readily reduced, leading to the fast formation of active species for AB hydrolysis. These findings provide some insight into the design of high-performance oxide-based catalysts for AB hydrolysis. Considering their low cost and high catalytic activity, Ni0.5Cu0.5Co2O4 nanoplatelets are a strong candidate catalyst for the production of hydrogen through AB hydrolysis in practical applications.

NiCu Bimetallic Nanoparticles on Silica Support for Catalytic Hydrolysis of Ammonia Borane: Composition-Dependent Activity and Support Size Effect

NiCu bimetallic nanoparticles (NPs) with different Ni/Cu compositions are controllably synthesized by tuning the ratio of Ni and Cu acetylacetonate precursors in the presence of oleylamine and trioctylphosphine. The similar particle size, monodispersity, and homogeneous alloying of the obtained NPs are confirmed by spectroscopic and microscopic analyses. When the bimetallic NPs together with the monometallic counterparts are used as catalysts for the hydrolysis of ammonia borane (AB), their catalytic activities are found to be composition-dependent. The best-performing Ni0.75Cu0.25 NPs show an activation energy of 34.2 kJ mol–1, which is among the lowest in reported non-noble-metal catalysts. This volcano-type activity trend is attributed to the alloying effect of NiCu that endows a favorable electronic structure toward the hydrolysis of AB. To investigate the catalytic effect of support particle size, a critical yet largely unexplored factor, we further deposit the Ni0.75Cu0.25 NPs onto six differently sized silica spheres in the size range 47–485 nm. It is found that the activity of NiCu/SiO2 catalysts increases progressively with decreasing SiO2 particle size, which is attributed to the less agglomeration and better stabilization of NiCu NPs enabled by SiO2 spheres with higher curvature and longer interparticle distance. Notably, the NiCu NPs supported on the smallest SiO2 exhibit a much higher turnover frequency of 1516 molH2 molmetal–1 h–1 compared to the unsupported NPs as well as an excellent reusability in the consecutive hydrolysis of AB, signifying the strong metal–support interactions. The results underline the importance of engineering alloy composition and support particle size for efficient catalytic hydrolysis of AB.

Low-cost CuFeCo@MIL-101 as an efficient catalyst for catalytic hydrolysis of ammonia borane

Trimetallic nanoparticles of non-noble Cu–Fe–Co with different molar ratios were successfully immobilized in the metal-organic frameworks (MIL-101) via an easy impregnation–reduction process. XRD, TEM, XPS, ICP-MS and BET methods were used to characterize the catalyst. Comparing to their bimetallic counterparts, Cu6Fe0.8Co3.2@MIL-101 demonstrates the best catalytic performance for dehydrogenation of ammonia borane by hydrolysis at 298 K Cu6Fe0.8Co3.2@MIL-101 shows a total turnover frequency (TOF) value of 23.2 molH2 molcatalyst−1 min−1 and an activation energy value of 37.1 kJ mol−1. The enhancement of catalytic activity was attributed to a synergistic effect among copper, cobalt and iron nanoparticles supported on MIL-101. In addition, the catalyst still exhibits good stability and magnetic recyclability after seven cycles. The low-cost catalyst has good prospect for application in the field of hydrogen storage.

In Situ Synthesis of NiCoP Nanoparticles Supported on Reduced Graphene Oxide for the Catalytic Hydrolysis of Ammonia Borane.

Developing highly efficient and stable noble-metal-free catalysts toward catalytic hydrolysis of ammonia borane (AB) for hydrogen storage is highly desirable, but still remains challenging. We report a simple and in situ co-reduction approach to synthesize bimetallic NiCoP nanoparticles (NPs) supported on reduced graphene oxide (rGO). Thanks to the strong electronic interaction between Ni, Co, and P, the as-synthesized Co89.8 Ni10.2 P11.7 /rGO catalyst exhibits superior catalytic performance towards hydrolysis of AB, with the turnover frequency value (TOF) of 18.6 min-1 , which is about 2.5 times higher than that of NiCo/rGO.

Novel activated carbon supported trimetallic PdCoAg nanoparticles as efficient catalysts for the hydrolytic dehydrogenation of ammonia borane

Activated carbon (AC) supported palladium, cobalt and silver nanoparticle (PdCoAg/AC) catalysts were prepared by in situ reduction of sodium borohydride (NaBH4) and characterized by various techniques such as X-ray diffraction (XRD), scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDX), Transmission electron microscopy (TEM) and X-ray Photoelectron Spectroscopy (XPS). The PdCoAg/AC catalyst is active in the hydrolysis of ammonia-borane (AB) even at low temperatures. Compared with mono- (Pd) and bi-metallic (PdCo) nanoparticles, this trimetallic (PdCoAg) structure showed greatly increased catalytic activity for AB hydrolysis. Their hydrolysis completion time was 50 s. This study also included full experimental details of kinetic data to determine the activation parameters (Ea, ΔH and ΔS) for the rate law and the catalytic hydrolysis of AB. In addition, the PdCoAg/AC catalysts had favorable catalytic activity also after seven runs. Hydrogen generation rate (HG), Ea, ΔH and ΔS were obtained at 25 °C as 4666.66 mL min−1g−1 (2 mmol AB and 50 mg PdCoAg/AC), 26.836 kJ mol-1, 29.416 kJ mol−1and –108.42 J mol−1K−1, respectively. In addition, the study showed that Pd0.6Co0.2CAg0.2/AC (Pd:Co:Ag atomic ratio = 6:2:2) showed the total turnover frequency (TOF) value of 6624 h−1. These results demonstrate that the PdCoAg/AC catalyst is a promising alternative in search of the practical application of AB as a hydrogen storage material for fuel cell applications.

Hexagonal CuCo₂O₄ Nanoplatelets, a Highly Active Catalyst for the Hydrolysis of Ammonia Borane for Hydrogen Production.

Catalytic hydrolysis of ammonia borane (AB) has been considered as an effective and safe method to generate hydrogen. Development of highly active and low-cost catalysts is one of the key tasks for this technology. In this work, hexagonal CuCo2O4 nanoplatelets with a thickness of approximately 55 nm were prepared. In AB hydrolysis, those nanoplatelets exhibited ultrahigh catalytic activity with turnover frequency (TOF) of 73.4 molhydrogen min−1 molcat−1. As far as we know, this is one of the highest TOF values ever reported for non-noble metal catalysts. In addition, the effects of viscosity and different alkalis on the hydrolysis were also investigated. It is revealed that high viscosity of the reaction medium will retard the hydrolysis reaction. The presence of NaOH, KOH, and Na2CO3 in the reaction solution is favorable for hydrolytic process. In contrast, NH3·H2O will slow down the hydrolysis rate of ammonia borane. This work can provide some novel insight into the design of catalysts with both high performance and low cost. Besides, some findings in the present study can also offer us some information about how to improve the hydrolysis rates by optimizing the hydrolysis condition.

Ru nanoclusters confined in porous organic cages for catalytic hydrolysis of ammonia borane and tandem hydrogenation reaction.

The fabrication of narrow-sized metal nanoclusters for heterogeneous catalysis has attracted widespread research attention. Nevertheless, it is still a significant challenge to fabricate highly dispersed metal-nanocluster-based catalysts with high activity and stability. In this study, 1,3,5-benzenetricarboxylate and 1,2-diaminocyclohexane were used as precursors to fabricate porous organic cages (POCs), CC3-R. CC3-R exhibited a high specific surface area and a microporous-mesoporous structure. In addition, ultrafine Ru nanoclusters were successfully encapsulated in CC3-R with high dispersion via impregnation and subsequent reduction, affording Ru nanoclusters with a precisely controlled size of ∼0.65 nm. As-obtained Ru(1.45%)@CC3-R exhibited significantly enhanced catalytic activities toward the hydrolysis of ammonia borane (AB) and exhibited high conversion and selectivity for the tandem hydrogenation of nitroarenes and hydrogenation of quinoline in water under mild conditions. In addition, the Ru(1.45%)@CC3-R catalyst exhibited high stability and good recyclability. This study should provide a novel strategy for fabricating highly dispersed ultrafine nanocluster-based catalysts for various catalysis applications.