Efficient Catalysts For Hydrogen Generation Research Articles

Salts Induced Formation of Hierarchical Porous ZIF‐8 and Their Applications for CO2 Sorption and Hydrogen Generation via NaBH4 Hydrolysis

AbstractDespite the great potential of two different pore regimes (hierarchical porous (HP) structure), HP‐zeolitic imidazolate frameworks‐8 (HPZIF‐8) can be efficient catalysts for hydrogen generation via hydride hydrolysis, and as adsorbents for CO2 gas adsorption. Herein, HPZIF‐8, and leaf‐like ZIF (ZIF‐L) are synthesized via a simple and environmentally friendly procedure using layered hydroxide nitrate of zinc (Z5HN) as a metal source and simple inorganic salt as a modulator. Z5HN nanosheets undergo topotactic transformation to simonkolleite (Zn5(OH)8Cl2·H2O) that can be converted to the pure phase of HPZIF‐8. The concentration of the salts tunes the textural properties of the final product. Applications of HPZIF‐8 and ZIF‐L for CO2 sorption exhibit excellent adsorption properties with increases of 25% due to the presence of cations in the frameworks. ZIF‐8 shows exceptional high catalytic activity for hydrogen generation via the hydrolysis of sodium borohydride. The simple synthesis of ZIF‐8 as well as their good performance as adsorbent and catalyst ensure the potential for industrial and commercial uses.

Ru Nanoparticles Embedded in Cubic Mesoporous Silica SBA-1 as Highly Efficient Catalysts for Hydrogen Generation from Ammonia Borane

Cubic mesoporous silica SBA-1 functionalized with carboxylic acid (-COOH), namely S1B-C10, is used as a support to fabricate and confine Ru nanoparticles (NPs). The uniformly dispersed organic functional groups in SBA-1 are beneficial in attracting Ru cations, and as a result, homogenously distributed small sized Ru NPs are formed within the mesopores. The prepared Ru@S1B-C10 is utilized as a catalyst for H2 generation from the hydrolysis of ammonia borane (AB). The Ru@S1B-C10 catalyst demonstrates high catalytic activity for H2 generation (202 mol H2 molRu min−1) and lower activation energy (24.13 kJ mol−1) due to the small sized Ru NPs with high dispersion and the support’s interconnected mesoporous structure. The nanosized Ru particles provide abundant active sites for the catalytic reaction to take place, while the interconnected porous support facilitates homogenous transference and easy dispersal of AB molecules to the active sites. The catalyst demonstrates good recycle ability since the accumulation and leaking of NPs throughout catalysis can be effectively prevented by the support.

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.

Ru–Fe nanoalloys supported on N-doped carbon as efficient catalysts for hydrogen generation from ammonia borane

RuFe/N–C alloy catalysts generate a synergistic effect on the enhancement of intrinsic activity toward hydrolysis of ammonia borane.

PVP-Protected Pt-Ru Nanoparticles as Highly Efficient Catalysts for Hydrogen Generation from Hydrolysis of Sodium Borohydride

PVP-Protected Pt-Ru Nanoparticles as Highly Efficient Catalysts for Hydrogen Generation from Hydrolysis of Sodium Borohydride

Cotton stalk activated carbon-supported Co–Ce–B nanoparticles as efficient catalysts for hydrogen generation through hydrolysis of sodium borohydride

Porous cotton stalk activated carbons (CSAC) were prepared by phosphoric acid activation of cotton stalks in a fluidized bed. The CSAC-supported Co–B and Co–Ce–B catalysts were prepared by the impregnation-chemical reduction method. The samples were characterized by the nitrogen adsorption, XRD, FTIR and TEM measurements. The effects of the sodium borohydride (NaBH4) and sodium hydroxide (NaOH) concentrations, reaction temperature and recyclability on the rate of NaBH4 hydrolysis over the CSAC-supported Co–Ce–B catalysts were systematically investigated. The results showed that the agglomeration of the Co–Ce–B nanoclusters on the CSAC support surface was significantly reduced with the introduction of cerium. The CSAC-supported Co–Ce–B catalyst exhibited superior catalytic activity and the average hydrogen generation rate was 16.42 L min−1 g−1Co at 25 °C, which is higher than the most reported cobalt-based catalysts. The catalytic hydrolysis of NaBH4 was zero order with respect to the NaBH4 concentration, and the hydrogen generation rate decreased with the increase in the NaOH concentration. The activation energy of the hydrogen generation reaction on the prepared catalyst was estimated to be 48.22 kJ mol−1. A kinetic rate equation was also proposed.

Palladium Supported on Porous Chitosan-Graphene Oxide Aerogels as Highly Efficient Catalysts for Hydrogen Generation from Formate.

Adsorption of Pd(NH3)42+ in preformed chitosan–graphene oxide (CS-GO) beads and their subsequent reduction with NaBH4 afford well-dispersed, high dispersion (~21%) of uniformly sized Pd nanoparticles (~1.7 nm). The resulting Pd/CS-GO exhibits interesting catalytic activity for hydrogen generation by ammonium formate decomposition. The optimal GO proportion of 7 wt% allows reaching, at 60 °C, a turnover frequency above 2200 h−1—being outstanding among the highest values reported for this process to date. Interestingly, no formation of CO or CH4 was detected. The catalyst did not leach, although it underwent gradual deactivation, probably caused by the increase in the Pd average size that became over 3 nm after three uses. Our results are relevant in the context of efficient on-board hydrogen generation from liquid organic hydrogen carriers in transportation.

Effect of Pore Confinement of NaNH2 and KNH2 on Hydrogen Generation from Ammonia.

The development of efficient catalysts for hydrogen generation via ammonia decomposition is crucial for the use of ammonia as an energy carrier. Here, we report the effect of pore confinement of NaNH2 and KNH2 on ammonia decomposition catalysis. For the first time, Ni- or Ru-doped NaNH2 and KNH2 were confined in carbon nanopores using a combination method of solution impregnation and melt infiltration. Structure characterization indicates the nanoscale intimacy between transition metals and alkali metal amides inside the pores of the carbon support. As a result, 8 wt % Ni-doped NaNH2 and KNH2 nanocomposites give NH3 conversions of 79 and 60%, respectively at 425 °C, close to the performance of a 5 wt % Ru/C reference catalyst. 0.8 wt % Ru-doped nanocomposites exhibit even better catalytic performance, with about 95% NH3 conversion at a moderate temperature of 375 °C. The hydrogen production rates of these Ni- and Ru-doped nanocomposites in a pure NH3 flow are about 3–4 times higher than for the recently reported novel catalysts such as Ni–Li2NH and Ru–Li2NH/MgO. Interestingly, the apparent activation energies of the Ru- or Ni-based catalysts decrease 20–30 kJ mol–1 by co-confinement with alkali metal amides. The strategy of nanoconfinement of alkali metal amides in porous hosts may open a new avenue for effectively generating H2 from NH3 at low temperatures.

Electrospun Bimetallic NiCr Nanoparticles@Carbon Nanofibers as an Efficient Catalyst for Hydrogen Generation from Ammonia Borane.

In this study, we report on the fabrication and utilization of NiCr alloy nanoparticles (NPs)-decorated carbon nanofibers (CNFs) as efficient and competent non-precious catalysts for the hydrolytic dehydrogenation of ammonia borane (AB) at 25 ± 2 °C. The introduced NFs have been fabricated in one step using a high-temperature thermal decomposition of the prepared electrospun nanofiber mats (nickel acetate tetrahydrate, chromium acetate dimer, and polyvinyl alcohol) in an inert atmosphere. The chemical composition of the NFs with different proportions of Ni1−xCrx (x = 0.0, 0.1, 0.15, 0.2, 0.25, 0.3) was established via standard characterization techniques. These techniques proved the formation of disorder Cr2Ni3 alloy and carbon for all the formulations. The as-synthesized composite NFs exhibited a higher catalytic performance for AB dehydrogenation than that of Cr-free Ni–CNFs. Among all the formulations, the sample composed of 15% Cr shows the best catalytic performance, as more H2 was released in less time. Furthermore, it shows good stability, as it is recyclable with little decline in the catalytic activity after six cycles. It also demonstrates the activation energy, entropy (ΔS), and enthalpy (ΔH) with 37.6 kJ/mole, 0.094 kJ/mole, and 35.03 kJ/mole, respectively. Accordingly, the introduced catalyst has a lower price with higher performance encouraging a practical sustainable H2 energy application from the chemical hydrogen storage materials.

Template-free synthesis of porous Mo3P/MoP nanobelts as efficient catalysts for hydrogen generation

Hydrogen has attracted extensive attention as a potential alternative energy and many achievements have been made in the research of transition metal phosphide catalysts, but further improvements are still strongly demanded. In this report, we propose a novel strategy for the template-free synthesis of Mo3P/MoP porous nanobelts as efficient catalysts for hydrogen generation. The porous structures can give more active sites, and the presence of Mo3P can further improve the internal electron transfer ability through the strong bond. Thus, the porous Mo3P/MoP hybrid catalyst exhibits an outstanding hydrogen evolution activity and a good stability. This study may provide a facile and effective strategy for the improvement of transition metal phosphide catalysts by controlling the structures and compositions.

CuCo binary metal nanoparticles supported on boron nitride nanofibers as highly efficient catalysts for hydrogen generation from hydrolysis of ammonia borane

The application of hexagonal boron nitride materials in the field of catalysis has gradually attracted increasing attention. Herein we demonstrate the application of porous boron nitride nanofibers as a promising carrier for developing highly efficient catalysts for the catalytic hydrogenation of ammonia borane. Porous boron nitride nanofibers with high specific areas are utilized as a novel carrier to support and immobilize CuCo binary metal nanoparticles with average diameters below 10 nm. The prepared composite catalyst exhibits excellent catalytic activity on hydrogen production by ammonia borane hydrolysis. The hydrogen generation rate of Cu0.4Co0.6/boron nitride catalyst (with a particle loading weight of 15.6 wt%) is 3387.1 mL min−1·g−1, with a total turnover frequency value of 8.42 mol H2·(mol cat)−1·min−1 and a activation energy of 21.8 kJ mol−1. Theory study indicates that the synergistic effect of CuCo binary metals, as well as the strong interaction between boron nitride carrier and CuCo metal, leading to the enhanced catalytic activities of the catalyst. This study demonstrates that porous boron nitride has prospective application potentials in the field of catalytic hydrogen production of ammonia borane.

Molybdenum disulfide decorated palm oil waste activated carbon as an efficient catalyst for hydrogen generation by sodium borohydride hydrolysis

Development of cost-effective catalyst material with enhanced activity for hydrogen generation is highly desirable for hydrogen powered portable applications. In this work, molybdenum disulfide (MoS2) incorporated on palm oil waste activated carbon (POAC) was used as a novel catalyst for enhanced hydrogen production by sodium borohydride (NaBH4) hydrolysis. Hydrothermally synthesized MoS2/POAC catalyst composite was characterized by SEM, EDX, XRD, FTIR, Raman, TGA and Surface area analysis. Characterization studies revealed the uniform and complete synthesis of MoS2 nanoparticles on the POAC surface with crystallite size of 18.2 nm. The catalyst composite showed enhancement in thermal stability and reduction in specific surface area as compared with POAC. Hydrogen generation investigations showed ideal weight ratio of composite catalyst as 10:1 (w/w of POAC: MoS2) and optimal catalyst to feed weight ratio as 0.07. MoS2/POAC catalyst with 10 wt% of POAC loading recorded the maximum catalytic activity of 1170.66 mL/g min with lower activation energy of 39.1 kJ/mol. The catalyst composite exhibited virtuous reusability with a 28% loss in activity for nine cycle regeneration run. Thus, MoS2/POAC catalyst system is highly attractive for commercial applicability and is a potential candidate for enhanced hydrogen production through NaBH4 hydrolysis.

Monodisperse Ru[sbnd]Rh bimetallic nanocatalyst as highly efficient catalysts for hydrogen generation from hydrolytic dehydrogenation of methylamine-borane

In this study, the polyvinylpyrrolidone (PVP) stabilized Ru and Rh (Ru-Rh@PVP) nanocatalyst was prepared using the precursor materials of Ru, Rh and also PVP as a polymeric material, characterized and its catalytic activity was investigated by using in the hydrolytic dehydrogenation of methylamine-borane (MeAB) at room temperature. The structural and morphological properties of the Ru-Rh@PVP nanocatalyst was examined by using analytical techniques such as TEM/EELS, HRTEM, XPS, P-XRD and UV–Vis spectra. These analytical techniques revealed that RuRh based nanoparticles were well distributed on the PVP with a particle size of 3.42 ± 0.33 nm. The preparation of catalyst was done according to alcohol reduction technique and then prepared Ru-Rh@PVP nanocatalyst was tested in the hydrolytic dehydrogenation of methylamine-borane at various MeAB-Ru-Rh@PVP concentrations, temperatures and reusability performance at room temperature. The one of the best TOF (initial turnover frequency) and Ea (activation energy) values were found to be 206.2 min−1 and 43.5 kJ/mol, respectively.

Co[sbnd]Mo[sbnd]B nanoparticles supported on foam Ni as efficient catalysts for hydrogen generation from hydrolysis of ammonia borane solution

We report on CoMoB nanoparticles supported on foam Ni as catalysts for hydrogen generation from hydrolysis of ammonia borane (NH3BH3) solution. The CoMoB/foam Ni catalysts with different molar ratios of Co2+and MoO42− were synthesized via the electroless-deposition technique at ambient temperature. In order to analyze the phase composition, chemical composition, microstructure, and electron bonding structure of the as-prepared samples, powder X–ray diffraction (XRD), inductively coupled plasma-mass spectroscopy (ICP-MS), scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) were used. The results showed that CoMoB nanoparticles were variously dispersed on the surface of the foam Ni and the catalytic activity correlated with the molar ratio of Co2+ and MoO42−. The highest hydrogen generation rate was 5331.0 mL min−1 gcat−1 at 298 K, and the activation energy was calculated to be 45.5 kJ mol−1 toward the hydrolysis of NH3BH3 solution. The better catalytic activity was largely attributed to the smaller particle size, higher surface roughness and the novel three-dimensional cone-like architectures of the obtained samples. The kinetic results show that the hydrolysis of NH3BH3 is a first-order reaction in catalyst concentration. In addition, the reusability experiment exhibited that the catalytic activity was reduced after 5 cycles and the reason of the decay was also investigated.

Co-Mo nanoparticles loaded on three–dimensional graphene oxide as efficient catalysts for hydrogen generation from catalytic hydrolysis of sodium borohydride

Co-Mo particles were loaded on three dimensional graphene oxide (3DGO) carrier via a chemical reduction method to get a composite catalyst, Co-Mo/3DGO, for hydrogen generation from NaBH4 hydrolysis. Hydrolysis measurement shows that the ratio Co:Mo = 0.7:0.3 realizes a much higher hydrogen generation rate (HGR) of 7023.3mLH2⋅min−1⋅gM−1 , about 1.6 times of that for the Mo element undoped Co/3DGO (4394 mLH2.min−1.gM−1) catalyst. And the reaction activation energy is as low as 35.6 kJ mol−1. The as prepared Co0.7Mo0.3/3DGO catalyst disperses on 3DGO surface as smaller particles than Co/3DGO, and presents a waxberry like structure with more active sites for catalysis reaction, which enables the catalyst a superior catalytic activity. Besides abundant active sites, MoO3 supported active blend of Co and CoO is another reason for the higher activity.

Phosphane‐decorated Platinum Nanoparticles as Efficient Catalysts for H2 Generation from Ammonia Borane and Methanol

AbstractA series of narrowly dispersed Pt nanoparticles of 1.5–2.2 nm in size stabilized by bulky terphenylphosphane ligands has been synthesized by the organometallic method using [Pt(dba)2] as platinum source. These nanoparticles are highly efficient catalysts for hydrogen generation by methanolysis of ammonia borane (H3N ⋅ BH3), providing notable TOF values of up to 284 min−1 at 30 °C and low catalyst loadings (0.14–0.19 mol %). Furthermore, catalyst separation (after distillation of the H2‐depleted ammonium tetramethoxyborate (NH4B(OMe)4) and methanol) and recycling were proven to be feasible, although an erosion of the catalytic activity was observed after three catalytic runs. These Pt nanoparticles have also been used as catalysts for tandem dehydrogenation of ammonia borane and hydrogenation of N‐heterocycles, providing the reduction products of quinoline, phenanthridine, 2‐methylquinoxaline and acridine in >90 % yields under mild reaction conditions.

Novel NiPt alloy nanoparticle decorated 2D layered g-C3N4 nanosheets: a highly efficient catalyst for hydrogen generation from hydrous hydrazine

By virtue of the synergistic electronic effect among nickel, platinum, and g-C3N4 nanosheets (NSs), the prepared Ni0.6Pt0.4/g-C3N4 NSs exhibit improved dehydrogenation of hydrous hydrazine with a turnover frequency (TOF) value as high as 2194 h−1 at 323 K.

Bimetallic NiIr nanoparticles supported on lanthanum oxy-carbonate as highly efficient catalysts for hydrogen evolution from hydrazine borane and hydrazine

La2O2CO3-supported NiIr nanoparticles (NPs) have been facilely synthesized via a sodium–hydroxide-assisted reduction approach and used as highly efficient catalysts for hydrogen generation from hydrazine borane and hydrous hydrazine.

Cobalt nanoparticles supported on magnetic core-shell structured carbon as a highly efficient catalyst for hydrogen generation from NaBH4 hydrolysis

A novel recyclable cobalt nanocatalyst, supported on magnetic carbon with core-shell structure, was successfully synthesized by using wetness impregnation-chemical reduction method for hydrogen generation from hydrolysis of NaBH4. The resultant nanocomposite was characterized to determine the structural and physical-chemical properties by a series of analytical techniques such as FT-IR (Fourier transform infrared spectroscopy), XRD (X-ray diffraction), SEM (scanning electron microscope), EDX (energy-dispersive X-ray spectroscopy), TEM (transmission electron microscopy), etc. The results demonstrated that amorphous cobalt nanoparticles were homogeneously surrounded on the surface of the support due to having abundant hydrophilic groups (such as aldehyde and hydroxyl groups) on the surface of carbon layer for the effective immobilization of metal ions. The supported catalyst showed superior catalytic performance towards the hydrolysis reaction of NaBH4 at room temperature. The total rate of hydrogen generation and activation energy were calculated to be 1403 ml H2 gcat−1 min−1 and 49.2 kJ mol−1, respectively, which were comparable to the values of most cobalt-based catalyst reported for hydrogen production from hydrolysis of NaBH4. Additionally, reusability test revealed that the hydrogen in NaBH4 substrate could be completely released within 25 min with a minimum hydrogen generation rate of 832 ml H2 gcat−1 min−1 even after five runs of hydrolytic reaction, implying the as-prepared Co/Fe3O4@C composite could be considered as a promising candidate catalyst for portable hydrogen fuel system such as PEMFC (proton exchange membrane fuel cells).

Three-dimensional nitrogen-doped graphene hydrogel supported Co-CeOx nanoclusters as efficient catalysts for hydrogen generation from hydrolysis of ammonia borane

The development of highly active noble-metal-free catalysts for catalytic hydrolysis of ammonia borane is mandatory for its application in hydrogen storage. Herein, Co-CeOx nanoclusters have been successfully anchored on a three-dimensional nitrogen-doped graphene hydrogel (NGH) by a simple co-reduction method and further used as efficient catalysts to catalytic hydrolysis of ammonia borane at room temperature. Thanks to the strong synergistic electronic effect between Co and CeOx, as well as the strong metal-support interaction between Co-CeOx and 3D NGH, the as-synthesized Co-(CeOx)0.91/NGH catalyst exhibits superior catalytic activity toward hydrolysis of ammonia borane, with the turnover frequency (TOF) value of 79.5min−1, which is almost 13 times higher than that of Co/NGH, and higher than most of the reported noble-metal-free catalysts.