No description available.

Sodium borohydride reduces alkyl halides and their related tosylate derivatives in the order primary > secondary > tertiary, while the relative order of leaving-group ability is Ts⁻ ≥ I⁻ > Br⁻ > > Cl⁻. The yields obtained ranged from 90-100% for most simple, primary and secondary iodides, bromides, and tosylates, to 1-2% for the tertiary compounds. As in the case of the more reactive lithium aluminum hydride, the. reduction is believed to occur by an S_N2 displacement on carbon. The reduction of a series of para-substituted benzyl chlorides revealed that the electronic effects of groups ranging from p-methoxy to p-nitro had a rather small effect on the rate of reduction. Aryl halides arc reduced by sodium borohydride in yields dependent upon the particular halogen involved, the presence of other ortho and para electron-withdrawing substituents, and the reaction temperature, among other factors. The same relative order of dehalogenation displayed by the alkyl halides was found. Polyhalomethanes such as carbon tetrachloride react with sodium borohydride to give the monohydro and dihydro compounds as the major products, the former predominating. The exact mechanism of the reduction is as yet undetermined, as water apparently catalyzes the reaction in some unknown manner. / Master of Science

Le travail présenté dans cette thèse porte sur l'anode de la pile à combustible directe aux borohydrures (DBFC, selon l'acronyme anglais). Une première approche pour développer l'anode de la DBFC est d'étudier cette anode à l'intérieur du système global de la DBFC. Dans cette optique, des anodes composées des catalyseurs Pt/C et Pd/C ont été caractérisée en banc de test DBFC. D'autres facteurs ont aussi été étudiés, tels que la morphologie de l'anode et la stabilité des nanoparticules des catalyseurs.Le catalyseur d'anode de la DBFC doit idéalement exhiber une activité catalytique suffisante pour la réaction d'oxydation des borohydrures (BOR), tout en minimisant la production et l'échappement d'hydrogène gazeux durant la BOR. Ces aspects sont relativement difficiles à étudier en raison des nombreuses variables ne dépendant pas de l'anode dans un système DBFC réel. Une solution à ce problème consiste à isoler l'anode de la DBFC et de l'étudier en configuration demi-pile, avec un environnement d'étude mieux contrôlé. Les différentes méthodes pour évaluer un catalyseur d'anode de DBFC en demi-pile sont discutées, et des marqueurs sont proposés pour l'évaluation pertinente d'un catalyseur d'anode de DBFC par rapport aux résultats de la littérature.Une autre stratégie possible pour développer des catalyseurs adéquats d'anode de DBFC est de mieux comprendre le mécanisme de la BOR. Dans cette optique, la BOR est étudiée sur des électrodes modèles à base de platine. Chaque type d'électrode modèle permet de contrôler un paramètre précis de la surface catalytique, menant ainsi à différentes études de la BOR. La sensibilité de la BOR à la structure de surface catalytique est étudiée sur des électrodes massives de platine (polycristallin et monocristallin). L'empoisonnement de la surface active de Pt durant la BOR est étudié sur nanoparticules de Pt déposées sur substrat carbone vitreux plan. Des électrodes à trois dimensions ont également été réalisées : nanoparticules de Pt déposées sur nanofibres de carbone verticalement alignées. Le dépôt de différentes quantité de Pt a permis d'étudier l'influence de la densité en sites actifs de Pt sur la BOR. Les résultats obtenus sur ces électrodes modèles sont discutés avec ceux de la littérature, et un mécanisme pour la BOR sur Pt est proposé. Ce mécanisme est simulé en utilisant une modélisation de micro-cinétiques de type champs moyens. Les courbes simulées reproduisent les caractéristiques majeures des résultats expérimentaux. / The present work focuses on direct borohydride fuel cell (DBFC) anodes. A first approach to develop a suitable anode design for the DBFC consists in the study of the anode within the real DBFC system. In that frame, carbon-supported platinum and palladium nanoparticles are characterized and compared as anode electrocatalyst in DBFC configuration. Other variables such as the morphology of the anode and the stability of the catalyst nanoparticles are considered.The ideal DBFC anode catalyst should show a suitable electrocatalytic activity towards the borohydride oxidation reaction (BOR), without quantitative production/escape of gaseous hydrogen during the reaction. Studying these aspects is not straightforward using a real DBFC system, as the global behavior of the DBFC depends on numerous experimental variables external to the anode. In order to overcome this issue, a prospective anode catalyst can be isolated and specifically studied in half-cell configuration in a more controlled environment. The different methods possible for the evaluation of an electrocatalyst for the anode of the DBFC are discussed in this work, and benchmarks are proposed to compare a given material with the DBFC literature.Another strategy to develop suitable DBFC anode catalysts is to further understand the BOR mechanism. In that frame, the BOR is studied on model platinum-based electrodes with different levels of complexity. Bulk polycrystalline and single-crystals Pt flat electrodes enable to study the structure sensitivity of the BOR. The poisoning of the Pt active surface is investigated using Pt nanoparticles supported on flat glassy carbon substrate. Three-dimensional electrodes are also surveyed: Pt nanoparticles supported on vertically-aligned carbon nanofiber electrodes. The deposition of various amounts of Pt nanoparticles on the VACNF substrate enables to study the influence of the density of Pt active sites towards the BOR. The findings obtained using these model electrodes are gathered with previous results from the literature in order to propose a BOR mechanism on Pt. This mechanism is used in a mean-field microkinetics model. The simulated curves of this mechanism reproduce the main experimental features.

Ammonia borane and ammonium borohydride have been considered extensively as potential hydrogen storage materials. This thesis reports their structure and functional properties, emphasising the key role that dihydrogen bonding plays in both materials. The formation of a 'mobile phase' is considered to be the preliminary step in the decomposition of ammonia borane. The formation of this mobile phase has been studied using neutron diffraction, inelastic neutron spectroscopy and NMR. It has been found that in the mobile phase, 'end-to-end' flipping of the ammonia borane molecule occurs. This is an important precursor to the next step in the decomposition: the formation of the diammoniate of diborane. The dihydrogen bonding networks which occur in both the orthorhombic and the tetragonal phases of ammonia borane, and are the controlling factor in the decomposition process, were investigated using Density Functional Theory Molecular Dynamics (DFT-MD) simulations. It was hence shown that in the high-temperature tetragonal phase of ammonia borane, dihydrogen bonding is still an important stabilising interaction and there is little to distinguish between the three crystallographically distinct dihydrogen bonds. A closely related hydrogen storage material, ammonium borohydride, was also studied using the same techniques. Its low temperature phase progression was examined using variable temperature neutron diffraction. The vibrational modes of ammonium borohydride were assigned by comparing vibrational spectra determined using inelastic neutron spectroscopy with the results of DFT-MD simulations. Quasielastic neutron spectroscopy was used to show that both the ammonium and borohydride groups in ammonium borohydride perform discrete 'hopping' reorientational motions at a wide range of temperatures, and that the ammonium group has a mean residence time approximately 100 times less than that of the borohydride group. Hydrogen atom densities in the ammonium group were determined from DFT-MD simulations, and from refinements of high-resolution neutron diffraction data using cubic harmonic basis functions.

A reação de redução de oxigênio (RRO) e a reação de oxidação do borohidreto (ROB) foram estudadas em eletrólito alcalino em eletrodos formados por diversos tipos de óxidos de manganês dopados com Ni (II) dispersos sobre carbonos Monarch 1000, MM225 e E350. As técnicas de caracterização físico-química foram difração de raios X (DRX), microscopia eletrônica de transmissão de alta resolução (HR-TEM) equipado com espectrômetro de energia dispersiva de raios X (EDX). Já os estudos eletroquímicos compreenderam voltametria cíclica, curvas de polarização de estado quase estacionário além das técnicas de Espectroscopia de massas diferencial on line (DEMS) e Infravermelho com transformada de Fourier in situ (FTIR). Foi observada pequena inserção dos átomos de Ni na estrutura dos MnOx. A fase correspondente a NiMnOx/C está presente na forma de aglomerados nanocristalinos ou em forma de agulhas com tamanhos da ordem de 1,5 a 6,7 nm dependendo do tipo de carbono utilizado como substrato. Manganita (MnOOH) apresentou-se como fase preponderante para óxido de manganês disperso sobre carbono Monarch 1000 enquanto que para materiais dispersos sobre carbono MM225 e E350G a fase MnO2 esta presente em maior quantidade. Estudos eletroquímicos em camada fina utilizando eletrodo disco rotatório revelaram melhores atividade para a RRO e estabilidade para MnOx dopados com níquel. A RRO procede segundo o mecanismo peróxido, seguida pela reação de desproporcionação do íon HO2- formado. A extensão da reação de desproporcionação do íon HO2- aumenta com o aumento da quantidade de Ni. Sobre eletrocatalisadores suportados em carbonos MM225 e E350 a reação de desproporcionação é mais rápida e envolve um total de 4 e- por oxigênio molecular. As curvas de polarização para RRO obtidas na presença do íon BH4- mostraram que todos os materiais são tolerantes à presença do borohidreto. Resultados de DEMS on line e FTIR in situ mostraram que óxidos de manganês dopados com Ni além de serem ativos para RRO são também ativos para a ROB, porém há uma grande influência da composição e da morfologia dos materiais uma vez que, quando fases segregadas de Ni estão presentes nas amostras, a reação compete com a hidrólise heterogênea do BH4- levando a uma diminuição da eficiência faradaica. / The oxygen reduction reaction (ORR) and the borohydride oxidation reaction (BOR) were studied in alkaline medium on Ni (II) doped MnOx catalysts supported on different carbon powder substrates. Characterizations of physico chemical properties were made by X ray diffraction (XRD), high resolution transmition electronic microscopy (HR-TEM) equipped with X ray dispersive energy spectroscopy (EDS). Electrochemical studies involved cyclic voltammetry and oxygen reduction voltammograms. Also it was used Differential Electrochemical Mass Spectrometry on line (DEMS) and Fourier Transform Infra Red Spectrometry (FTIR) in situ. A small insertion of Ni atoms in the MnOx lattice was observed, this consisting of a true doping of the manganese oxide phase. The corresponding NiMnOx phase is present in the form of needles or agglomerates, with crystallite sizes in the order of 1.5-6.7 nm. Layered manganite (MnOOH) phase has been detected for the Monarch1000 supported NiMnOx material, while different species of MnOx phases are present at the E350G and MM225 carbons. Electrochemical studies in thin porous coating active layers in the rotating ring-disk electrode setup revealed that the MnOx catalysts present better ORR kinetics and electrochemical stability upon Ni doping. The ORR follows the so-called peroxide mechanism on MnOx/C catalysts, with the occurrence of minority HO2- disproportionation reaction. The HO2- disproportionation reaction progressively increases with the Ni content in NiMnOx materials. The catalysts supported on the MM225 and E350G carbons promote faster disproportionation reaction, thus leading to an overall four-electron ORR pathway. The results towards ORR in presence of sodium borohydride showed that all materials are tolerant to the presence of BH4- ion into some extent. DEMS on line and FTIR in situ showed that NiMnOx/C are also active toward the BOR, but there is a strong influence of the nature of the electrocatalysts with respect to the morphology, composition, the nature of the carbon substrate and the Ni load. Results indicate that the electrocatalysts containing segregate Ni phases, the bohohydride oxidation occurs together with the heterogeneous hydrolysis of the BH4- ion resulting in a decrease of the faradaic efficiency.

PtBi/C e PdBi/C foram preparados em diferentes razões atômicas (100:0, 90:10, 80:20, 70:30, 60:40 e 50:50) pelo método de redução via borohidreto de sódio (com adição total da solução de borohidreto em uma única etapa) utilizando H2PtCl6.6H2O, Pd(NO3)2, (BiNO3)3.5H2O como fonte de metais, Vulcan® (XC72-Cabot) como suporte de carbono e com uma carga metálica correspondente a 20% em massa. Os eletrocatalisadores obtidos foram caracterizados por difração de raios-X (DRX), microscopia eletrônica de transmissão (MET) e voltametria cíclica (VC). A atividade dos diferentes materiais preparados para a oxidação eletroquímica do ácido fórmico foi realizada em eletrólito ácido e alcalino utilizando-se as técnicas de voltametria cíclica, e cronoamperometria. Para estes estudos foi utilizado a técnica do eletrodo de camada fina porosa. A caracterização eletroquímica permitiu comparar o desempenho eletroquímico da platina e paládio, além de avaliar o benefício da presença do bismuto nas razões atômicas propostas. Os difratogramas de raio-X (DRX) confirmaram para todos os compostos de PtBi/C e PdBi/C a formação da estrutura cúbica de face centrada (cfc) característicos da rede cristalina da platina e do Paládio respectivamente. Outros picos encontrados foram associados a presença de fases de óxido de bismuto em ambos os compostos, PtBi/C e PdBi/C. A microscopia eletrônica de transmissão (MET) indicou que a presença de maiores teores de bismuto não acarretaram em aumento do tamanho médio da partícula. Os resultados eletroquímicos em meio alcalino indicaram que ainda é necessário uma otimização da concentração de ácido fórmico para que possamos observar melhores resultados quanto à adição de bismuto na platina ou paládio, no entanto os estudos em meio ácido mostraram o efeito benéfico da adição de bismuto tanto para platina quanto para o paládio. / PtBi/C and PdBi/C were prepared with different atomic ratios (100:0, 90:10, 80:20, 70:30, 60:40 and 50:50) by sodium borohydride reduction method (with total addition of the borohydride solution in just one step) using H2PtCl6.6H2O, Pd(NO3)2, (BiNO3)3.5H2O as source of metals, Vulcan® (XC72-Cabot) as carbon support and a metallic charge correspondent to 20% mass. The obtained electrocatalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and cyclic voltammetry (CV). The activity of the different materials used for the formic acid electrochemical oxidation was performed in acid and alkaline electrolyte through cyclic voltammetry and chronoamperometry, using the porous thin-film electrode technique. The electrochemical characterization allowed for the comparison between the platinum and palladium electrochemical performance, as well as the evaluation of the benefit of having bismuth in the proposed atomic ratios. The X-ray diffraction (XRD) diffractograms confirmed, for every PtBi/C and PdBi/C compounds, the formation of the face-centered cubic structure (fcc) distinctive to platinum and palladiums crystalline net, respectively. Other peaks were found associated to the presence of bismuth oxide phases in both compounds, PtBi/C and PdBi/C. The transmission electron microscopy (TEM) indicated that a higher bismuth presence did not result in a larger particle size. The electrochemical results in alkaline medium indicated that an optimization on formic acid concentration is still necessary so that better results concerning bismuth addition to platinum or palladium could be observed, although the studies done in acid medium presented the beneficial effect of bismuth addition to both platinum and palladium.

The use of microporous materials with ordered porous structures as the hosts to stabilize metal nanoclusters has attracted particular interest in the catalysis because the pore size restriction could confine the growth of nanoclusters and lead to an increase in the percentage of catalytically active surface atoms. In this dissertation we report the preparation, characterization and the investigation of the catalytic performance of zeolite framework stabilized ruthenium(0) nanoclusters in the hydrolysis of sodium borohydride and the hydrogenation of aromatics. The zeolite framework stabilized ruthenium(0) nanoclusters were prepared by borohydride reduction of ruthenium(III)-exchanged zeolite-Y in aqueous solution at room temperature and isolated as black powders. Their characterization by using ICP-OES, XRD, TEM, ZC-TEM, HR-TEM, TEM-EDX, SEM, XPS, DR-UV-vis, far-IR, mid-IR, Raman spectroscopy, N2 adsorption-desorption technique and (P(C6H11)3)/(PC6H11O3) poisoning experiments reveal the formation of ruthenium(0) nanoclusters within the zeolite cages as well as on the external surface of zeolite without causing alteration in the framework lattice or loss in the crystallinity. The catalytic performance of zeolite framework stabilized ruthenium(0) nanoclusters depending on the various parameters was tested in the hydrolysis of sodium borohydride and the hydrogenation of aromatics. The important results obtained from these experiments can be listed as follows: (i) the zeolite framework stabilized ruthenium(0) nanoclusters provide a record total turnover number (103200 mol H2/mol Ru) and turnover frequency (33000 mol H2/mol Ru&bull / h) in the hydrolysis of sodium borohydride at room temperature, (ii) they also catalyze the same reaction in the basic medium (in 5 wt % NaOH solution) at room temperature with the unprecedented catalytic activity (4000 mol H2/mol Ru&bull / h) and lifetime (27200 mol H2/mol Ru), (iii) the isolated and vacuum dried samples of zeolite framework stabilized ruthenium(0) nanoclusters are active catalysts in the hydrogenation of cyclohexene, benzene, toluene and o-xylene in cyclohexane, they provide TOF values of 6150, 5660, 3200, and 1550 mol H2/mol Ru&bull / h, respectively under mild conditions (at 22.0 &plusmn / 0.1 &deg / C, and 40 &plusmn / 1 psig of initial H2 pressure), (iv) more importantly, the zeolite framework stabilized ruthenium(0) nanoclusters are the lowest temperature, most active, most selective (100 % selectivity with complete conversion) and longest lifetime catalyst hitherto known for the hydrogenation of benzene to cyclohexane in the solvent-free system (TTON of 2420 and TOF of 1040 mol benzene/mol Ru&bull / h) under mild conditions (at 22.0 &plusmn / 0.1 &deg / C, and 40 &plusmn / 1 psig of initial H2 pressure), (v) moreover, the resultant ruthenium(0) nanoclusters exhibit high durability throughout their catalytic use against agglomeration and leaching. This significant property makes them reusable catalyst without appreciable loss of their inherent activity.

Recent study has shown that ruthenium(III) acetylacetonate acts as a homogeneous catalyst in the hydrolysis of sodium borohydride. When two equivalents of trimethylphosphite per ruthenium is added to the reaction solution containing sodium borohydride and ruthenium(III) acetylacetonate in the mixture of water and tetrahydrofuran, the rate of hydrogen generation is practically stopped (or reduced to the level of self hydrolysis). However, the catalytic hydrogen evolution of sodium borohydride restarts at an unexpectedly high rate in a certain period of time (induction time) after addition of trimethylphosphite. Consequently, trimethylphosphite known to be a poison in the hydrolysis, is involved in the formation of a new active catalyst (ruthenium species containing trimethylphosphite ligands) which has much higher catalytic activity in comparison with sole ruthenium(III) acetylacetonate. The same rate enhancement is observed by addition of two equivalents of triphenylphosphite per ruthenium into the medium. Varying the phosphorus compound affects not only the life time of catalyst but also the kinetic and activation parameters of the hydrolysis of sodium borohydride. However, varying the mole ratio of phosphorus compound to ruthenium does not affect the rate of hydrolysis or in other words, the rate of hydrogen generation is independent of phosphite concentration. Trans- and cis-[Ru(acac)2{P(OMe)3}2] complexes do not show significant catalytic activity in hydrogen generation of sodium borohydride. However, catalytic activity of cis-isomer is highly increased in the presence of two equivalents of trimethylphosphite, showing that the active catalyst formed during hydrolysis of sodium borohydride starting with Ru(acac)3 or cis-[Ru(acac)2{P(OMe)3}2], has more than two phosphine ligands. For the first time, a ruthenium(I) complex was isolated from aqueous solution after finishing the catalytic hydrolysis of sodium borohydride starting with ruthenium(III) acetylacetonate and trimethylphosphite. Hydridotetrakis(trimethylphosphite)ruthenium(I), [Ru{P(OMe)3}4H] was isolated and characterized by single crystal X-ray diffraction, Mass, UV-visible, FTIR, 1H, 13C and 31PNMR spectroscopy. Following the catalytic reaction by UV-Visible spectroscopy shows in-situ formation of a Ru(II) species which is mostly converted back to ruthenium(III) acetylacetonate after hydrolysis reaction along with formation of [Ru{P(OMe)3}4H] complex as a minor product. Although Ru(II) species could not be isolated, adding 1 equivalent of 2,2&#039 / -bipyridine yielded [Ru(acac)(bipy){P(OMe)3}H] complex which could be isolated and characterized by Mass, UV-Visible, FTIR, 1H, 13C and 31PNMR spectroscopy. In-situ generated Ru(II) species has much higher catalytic activity in comparison with its stabilized form [Ru(acac)(bipy){P(OMe)3}H] or [Ru{P(OMe)3}4H] complex. Conclusively, the fac-[Ru(acac){P(OMe)3}3H] complex is believed to be the in-situ generated Ru(II) species and the active catalyst in the hydrolysis of sodium borohydride.

Because of the growing concerns over the depletion of fossil fuel supplies, environmental pollution and global warming caused by a steep increase in carbon dioxide and other greenhouse gases in the atmosphere, much attention has been given to the development of renewable energy sources that are the only long-term solution to the energy requirements of the world&rsquo / s population, on the way towards a sustainable energy future. Hydrogen has been considered as a clean and environmentally benign new energy carrier for heating, transportation, mechanical power and electricity generation. However, the lack of effective, safe, and low-cost hydrogen storage materials for mobile, portable, and stationary applications is one of the major hurdles to be overcome for the implementation of hydrogen economy. Among various solid state hydrogen storage materials, chemical hydrogen storage materials such as sodium borohydride (NaBH4) and ammonia borane (H3NBH3) have received much attention as promising candidates for fuel cell applications under ambient conditions due to their high gravimetric and volumetric hydrogen storage capacities. Both sodium borohydride and ammonia borane generate hydrogen upon hydrolysis in the presence of suitable metal catalysts. Transition metal nanoclusters can be used as active catalysts to catalyze the hydrolysis reactions of sodium borohydride and ammonia borane for hydrogen generation since they exhibit unique properties that differ from their bulk counterparts. Although the catalytic activity of metal nanoclusters increases with decreasing particle size, they are unstable with respect to agglomeration into the bulk metal leading to a significant decrease in activity in their catalytic applications. Therefore, the exploitation of microporous and mesoporous materials with ordered porous structures as hosts to encapsulate metal nanoclusters has attracted great interest since the pore size restriction of these host materials could limit the growth of nanoclusters leading to an increase in the percentage of the catalytically active surface atoms. In this dissertation, we report the preparation, characterization and the investigation of the catalytic activities of zeolite confined cobalt(0) nanoclusters in the hydrolysis of sodium borohydride and ammonia borane. The zeolite confined cobalt(0) nanoclusters were prepared by the reduction of cobalt(II)-exchanged zeolite-Y by sodium borohydride in aqueous solution at room temperature with no alteration in the framework lattice or loss in the crystallinity. The characterization of zeolite confined cobalt(0) nanoclusters were done by using inductively coupled plasma optical emission spectroscopy (ICP-OES), X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), diffuse reflectance UV-visible spectroscopy (DR-UV-Vis), infrared spectroscopy (IR), Raman spectroscopy, and N2 adsorption-desorption technique. The catalytic activity of zeolite confined cobalt(0) nanoclusters and the kinetics of hydrogen generation from the hydrolysis of sodium borohydride and ammonia borane were studied depending on catalyst concentration, substrate concentration and temperature. The rate laws and the activation parameters (Arrhenius activation energy, Ea / activation enthalpy, &Delta / H# / and activation entropy, &Delta / S#) for both catalytic hydrolysis reactions were calculated from the obtained kinetic data.

The property transition metal nanoclusters are more active catalysts than their bulk counterparts because of increasing proportion of surface atoms with decreasing paricle size. The development of efficient and economical catalysts to further improve the kinetic properties under moderate conditions is therefore important for the practical application of nanoclusters as catalyst in the hydrogen generation from hydrolysis of ammonia borane this. In this regard, the development of active iron catalysts is a desired goal because it is the most ubiquitous of the transition metals, the fourth most plentiful element in the Earth&rsquo / s crust. In this dissertation, we report the preparation, characterization and investigation of the catalytic activity of the water soluble polymer stabilized iron(0) nanoclusters. They were prepared from the reduction of iron(III) chloride by a mixture of sodium borohydride (NaBH4, SB) and ammonia borane (H3NBH3, AB) mixture in the presence of polyethylene glycol (PEG) as stabilizer and ethylene glycol as solvent at 80 &deg / C under nitrogen atmosphere. PEG stabilized iron(0) nanoclusters were isolated from the reaction solution by centrifugation and characterized by SEM, EDX, TEM, HRTEM, XRD, UV-Vis, ICP-OES and FT-IR techniques. PEG stabilized iron(0) nanoclusters have almost uniform size distribution with an average particle size of 6.3 &plusmn / 1.5 nm. They were redispersible in water and yet highly active catalyst in hydrogen generation from the hydrolysis of AB. They provide a turnover frequency of TOF = 6.5 min-1 for the hydrolysis of AB at 25.0 &plusmn / 0.5 &deg / C. The TOF value is the best ever reported among the Fe catalyst and comparable to other non-noble metal catalyst systems for the catalytic hydrolysis of AB. Kinetics of hydrogen generation from the hydrolysis of AB in the presence of PEG stabilized iron(0) nanoclusters were also studied by varying the catalyst concentration, substrate concentration, and temperature. This is the first kinetic study on the hydrolysis of AB in the presence of an iron catalyst. Moreover, PEG stabilized iron(0) nanoclusters can be separated magnetically from the catalytic reaction solution by using a magnet and show catalytic activity even after tenth run.