Hydrolysis Of Sodium Borohydride Research Articles

Graphene-Modified Co-B-P Catalysts for Hydrogen Generation from Sodium Borohydride Hydrolysis.

Sodium borohydride (NaBH4) is considered a good candidate for hydrogen generation from hydrolysis because of its high hydrogen storage capacity (10.8 wt%) and environmentally friendly hydrolysis products. However, due to its sluggish hydrogen generation (HG) rate in the water, it usually needs an efficient catalyst to enhance the HG rate. In this work, graphene oxide (GO)-modified Co-B-P catalysts were obtained using a chemical in situ reduction method. The structure and composition of the as-prepared catalysts were characterized, and the catalytic performance for NaBH4 hydrolysis was measured as well. The results show that the as-prepared catalyst with a GO content of 75 mg (Co-B-P/75rGO) exhibited an optimal catalytic efficiency with an HG rate of 12087.8 mL min−1 g−1 at 25 °C, far better than majority of the findings that have been reported. The catalyst had a good stability with 88.9% of the initial catalytic efficiency following 10 cycles. In addition, Co-, B-, and P-modified graphene showed a synergistic effect improving the kinetics and thermodynamics of NaBH4 hydrolysis with a lower activation energy of 28.64 kJ mol−1. These results reveal that the GO-modified Co-B-P catalyst has good potential for borohydride hydrolysis applications.

Modulating valence band to enhance the catalytic activity of Co-Cr-B/NG for hydrolysis of sodium borohydride

In this work, amorphous Co-Cr-B/NG catalysts were prepared by the chemical reduction method. A descriptor of "valence band center" was introduced to the NaBH4 hydrolysis reaction to investigate the relationship between the valence band and the catalytic activity of amorphous Co-Cr-B/NG catalysts. The outcomes show that the valence band center of the Co-Cr-B/NG hybrids has been significantly changed after the Cr content is regulated by the preparation process, which can facilitate the modulation of the electronic structure of the catalysts. The hydrogen release rate shows a shape of a volcano with the valence band center. The hydrolysis performance test results of the optimum catalyst demonstrated that the hydrogen release rate of NaBH4 water at 25 °C was 2231.7 mL·min−1·g−1 with an activation energy of 38.41 KJ·mol−1, according to the volcano curve.

Investigation of Hydrogen Production from Sodium Borohydride in the Presence of Ni/Al2O3

With the increasing trend towards the use of renewable energy and the encouragement of international agreements due to environmental effects, the world tends to provide the energy it needs from renewable sources. Hydrogen is an environmentally friendly energy carrier that is produced from various energy sources and can be a sustainable solution to energy needs. Catalyst evaluation studies are carried out in studies that release high purity hydrogen by hydrolysis of metal hydrides such as sodium borohydride (NaBH4), and potassium borohydride (KBH4). In this study, Al2O3 supported Ni catalysts were synthesized by the impregnation method and the catalysts were characterized by applying X-Ray Diffractometry (XRD), X-Ray Fluorescence (XRF), Scanning Electron Microscopy (SEM), and Brunauer-Emmett-Teller (BET) methods. The performance of the catalysts was evaluated in the production of hydrogen by the hydrolysis of sodium borohydride. The influences of reaction temperature (20, 40, and 60 °C) and Ni content of the catalyst (20, 30, and 40 %) on the hydrolysis reaction was investigated under experimental conditions of 100 mg NaBH4, 100 mg catalyst, 5 mL 0.25 M NaOH. The highest hydrogen yield (100%) and hydrogen production rate (364.3 mL/gcat.min) was obtained with 40% Ni/Al2O3 catalyst at 60 °C reaction temperature.

A novel Dy3+ modified Zn2Ti3O8 nanoparticles for efficient hydrogen production photocatalysis

Novel Dy 3+ :Zn 2 Ti 3 O 8 (Dy 3+ :ZTO) nano-photocatalysts with different Dy 3+ concentrations were applied to enhance the photocatalytic hydrogen generation activity from sodium borohydride hydrolysis reaction. XRD and Raman measurements confirm the formation of cubic Zn 2 Ti 3 O 8 phase as a major phase in addition to minor TiO 2 phase. The analysis of XPS spectra shows the existence of lattice oxygen (LO) and non-lattice oxygen (NLO) where 0.07 mol Dy 3+ :ZTO has the highest percentage of NLO compared to the undoped photocatalyst. The energy gap value decreases with increasing doping concentrations (3.137 eV for 0.07 mol Dy 3+ :ZTO). The degree of disorder, represented by Urbach energy, has an optimum high value (0.169 eV) for 0.07 mol Dy 3+: ZTO. The photoluminescence studies revealed that Dy 3+ dopant can effectively separate the photogenerated electron/hole pairs in the ZTO. These photocatalysts have strong photocatalytic hydrogen generation. The most active nano-photocatalyst towards hydrogen generation was 0.07 mol Dy 3+ : ZTO (5.6 mmol/g). The highest photocatalytic activity for 0.07 mol Dy 3+ : ZTO are attributed to the lower recombination rate associated with the higher disorder and oxygen vacancies relative to the undoped photocatalyst. The stability and reusability of the most active photocatalyst were investigated. The results confirm that the developed photocatalyst has good durability in hydrogen generation reaction. The results, moreover, revealed that Dy 3+ : ZTO nano-photocatalyst is a promising nanomaterial in the field of energy production. Graphical illustration for the hydrogen generation. • Novel Dy 3+ :Zn 2 Ti 3 O 8 (Dy 3+ :ZTO) nano-photocatalysts were prepared. • Dy 3+ dopant can effectively separate the photogenerated carriers in the ZTO. • Dy 3+ :ZTO enhances the photocatalytic activity of hydrogen generation. • Catalyst reusability and stability of 0.07 mol Dy 3+ :ZTO was tested.

Hydrogen production via sodium borohydride hydrolysis catalyzed by cobalt ferrite anchored nitrogen-and sulfur co-doped graphene hybrid nanocatalyst: Artificial neural network modeling approach

The sluggish kinetics of the Sodium borohydride (NaBH4) hydrolysis process particularly in alkaline conditions requires the design of high-performance low-cost catalysts. Herein, it was aimed to tailor cobalt ferrite anchored nitrogen-and sulfur-doped graphene architecture (CoFe2O4 @N,S-G) via a facile production pathway, to explore its potential application as a catalyst in alkaline NaBH4 hydrolysis reaction for hydrogen production, and to develop an optimal artificial neural network (ANN) architecture to predict hydrogen production rate. In this regard, the influence of several variables such as reaction temperature, NaBH4 concentration, and catalyst loading was explored to determine the optimal operational conditions for effective hydrogen generation. Furthermore, the performance metrics of ANN topologies were investigated to establish the best ANN model for predicting hydrogen generation rate under different operational conditions. The experimental results offered the outstanding catalytic activity of CoFe2O4 @N,S-G towards NaBH4 hydrolysis with the volumetric hydrogen production rate of 8.5 L.min−1.gcat−1 at 25 ℃, and catalyst loading of 0.02 g, and 1.0 M NaBH4 concentration. The CoFe2O4 @N,S-G nanocatalyst was found to retain 94.9% of its initial catalytic activity after 5 consecutive uses, according to the reusability tests. The optimum performance metrics that were determined by the mean squared error (MSE) of 0.00052 and the coefficient of determination (R2) of 0.9989 were achieved for the ANN model with the configuration of 3–10–5–1 trained by Levenberg-Marquardt backpropagation algorithm. The activation function of tansig and purelin functions at hidden and output layers, respectively. The findings revealed that the experimental data were in harmony with the ANN-predicted one, thereby inferring the optimized ANN model could be employed in the forecasting of hydrogen production rate at various operational conditions.

A novel and active ruthenium based supported multiwalled carbon nanotube tungsten nanoalloy catalyst for sodium borohydride hydrolysis

At present, a novel and active catalyst, RuW/MWCNT catalyst, was successfully synthesized to complete the hydrolysis reaction of sodium borohydride (NaBH4). The activity of Ru catalyst was increased by adding tungsten (W) to ruthenium (Ru) on multi-walled carbon nanotube (MWCNT) support. Surface characterization of the catalyst was performed with scanning electron microscope (SEM-EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmissing electron microscope (TEM) analysis methods. SEM-EDX revealed that RuW (95:5) catalyst metal ratio was obtained at desired nominal ratio. XRD characterization revealed that W addittion to the Ru structure increased its activity by forming an alloy. W addition Ru altered the electronic structure of the Ru. Parameters affecting the hydrolysis performance of RuW/MWCNT catalyst such as temperature, amount of catalyst, NaBH4 concentration and sodium hydroxide (NaOH) concentration were investigated. Adding NaOH to the reaction vessel reduced the activity of the RuW/MWCNT catalyst. From the hydrolysis measurements, the activation energy of RuW(95–5)/MWCNT catalyst was found to be 16.327 kjmol−1, the reaction order as 0.61 and the initial rate as 95,841,4 mL H2gcatmin−1. The stability of the RuW/MWCNT catalyst was tested using 5 times and it was observed that this novel RuW/MWCNT catalyst could complete the hydrolysis reaction despite repeated use.

Protection and confinement effect of carbon on Co/CoxOy nano-catalyst for efficient NaBH4 hydrolysis

The hydrolysis of sodium borohydride (NaBH4) over catalysts is a promising method to produce hydrogen. Although Co-based catalysts exhibit high activity for NaBH4 hydrolysis, they are still far from satisfying practical applications, especially their poor durability in alkaline media. Herein, a carbon shell structure was designed and synthesized to improve the stability of the mixture of Co0 and CoxOy nanofilms (Co/CoxOy@C) during NaBH4 hydrolysis via a facile polymerization-pyrolysis strategy with Co/CoxOy nanofilms as the precursor. As a result, the Co/CoxOy@C catalyst can achieve a remarkable H2 generation rate of 4348.6 mL min−1 gCo−1 with a low activation energy of 43.6 kJ mol−1, which is superior to most previously reported catalysts. Moreover, the catalyst shows high stability with an H2 generation-specific rate of 79% after five cycles. The excellent performance of carbon substrate can well prevent the agglomeration of Co-based nanoparticle and improve the corrosion resistance of the active Co to BO2− and OH−. This work would widen the road for the preparation of nanoconfined catalysts, which has prospective application potentials for H2 production from NaBH4 hydrolysis.

REGULARITIES OF HYDROGEN GENERATION BY HYDROLYSIS OF SODIUM BOROHYDRIDE ON IMMOBILIZED PLATINUM CATALYSTS

Sodium borohydride hydrolysisis one of the most productive hydrogengeneration methods, which can be used, inparticular, to power fuel cells with a hydrogenanode. In alkaline solutions, the interaction of NaBH4 with water practically does not occur, which makes it possible to store such solutions for a longtime. However, in the presence of catalysts, the borohydride hydrolysis reaction actively proceeds at room temperature with the formation of hydrogenand sodium metaborate. More than 300 homogeneous and heterogeneous catalysts for the hydrolysis of sodium borohydride are known, among which the most active metal catalysts are nanodispersed rhodium, ruthenium, and platinum immobilized on various substrates. The activity of such catalysts depends on the conditions of the reduction and immobilization of metals, the nature of used precursors, the amount of active phase of the catalyst, and the type of substrate. In this work, platinum catalysts immobilized on several substrates are developed, and the regularities of hydrolysis of sodium borohydride in alkaline solution when using such catalysts in flowing flat and cylindrical reactors are investigated. Using various methods, platinum was deposited on carbon black and carbon cloth, onactivated granular carbon, on titanium crumb, and on synthetic cordierite of honey combstructure with surface, previously modified by alumina. It is shown that nanodisperse platinum catalysts immobilized on carbon black and carbon cloth and especially on synthetic cordierite of cellular structure with surface previously modified by Al2O3 layer are active and reliable. The average rate of hydrogen evolution during hydrolysis of NaBH4 on such catalysts increases with increasing flow rate of its solution through the reactor, but the degree of conversion of sodium borohydride decreases due to the reduced duration of contact of the solution with the catalyst. Nanodisperse platinum catalysts on surface-modified cordierite provide a highandstable rate of hydrogengeneration with moderate heating of NaBH4 solution (60±5°C). The use of hydrogen generators with such catalysts in combination with fuel cell batteries is promising for the creation of autonomous powers ources.

Composite NiFe2O4 Catalyst for Sodium Borohydride Hydrolysis

Nickel ferrites composite catalysts with the spinel structure were synthesized by the coprecipitation method. Nickel ferrites were deposed on the surface of industrial active carbon. The temperature of final calcination in inert media was 400, 500, and 600°C. The trevorite phase was determined by XR-diffraction; the ratio of Ni to Fe was checked by luminescent analysis, it consisted ~0.61. Crystallites sizes varied in the range from 218 to 252 nm and decreased with an increase in the calcination temperature. It was found that the rate of hydrogen evolution in the reaction of sodium borohydride hydrolysis increases with the reaction temperature increasing; catalysts obtained at lower calcination temperatures showed higher catalytic activity. The maximum Hydrogen Generation Rate (2181 ml×min-1×g-1) was observed for nickel ferrite deposited on the active carbon and calcined at a temperature 400oC; the activation energy of the reaction in the presence of this composite ferrite consisted ~50 kJ×mol-1.

Magnetically Recovered Co and Co@Pt Catalysts Prepared by Galvanic Replacement on Aluminum Powder for Hydrolysis of Sodium Borohydride.

Magnetically recovered Co and Co@Pt catalysts for H2 generation during NaBH4 hydrolysis were successfully synthesized by optimizing the conditions of galvanic replacement method. Commercial aluminum particles with an average size of 80 µm were used as a template for the synthesis of hollow shells of metallic cobalt. Prepared Co0 was also subjected to galvanic replacement reaction to deposit a Pt layer. X-ray diffraction analysis, X-ray photoelectron spectroscopy, scanning electron microscopy, and elemental analysis were used to investigate catalysts at each stage of their synthesis and after catalytic tests. It was established that Co0 hollow microshells show a high hydrogen-generation rate of 1560 mL·min−1·gcat−1 at 40 °C, comparable to that of many magnetic cobalt nanocatalysts. The modification of their surface by platinum (up to 19 at% Pt) linearly increases the catalytic activity up to 5.2 times. The catalysts prepared by the galvanic replacement method are highly stable during cycling. Thus, after recycling and washing off the resulting borate layer, the Co@Pt catalyst with a minimum Pt loading (0.2 at%) exhibits an increase in activity of 34% compared to the initial value. The study shows the activation of the catalyst in the reaction medium with the formation of cobalt–boron-containing active phases.

Exergy and energy analysis of hydrogen production by the degradation of sodium borohydride in the presence of novel Ru based catalyst

Chemically possible hydrogen storage material of the most important and widely used metal hydride compound is sodium borohydride. A current research issue is the development of systems that allow regulated hydrogen generation employing appropriate catalysts for the creation of hydrogen gas from the hydrolysis of sodium borohydride (NaBH4). In this study, controlled hydrogen production from alkali solution of NaBH4 was aimed. On hydrogen generation rate (HGR), the effects of NaBH4 and alkaline solution concentrations, catalyst quantity, and temperature were examined. Considering the energy and exergy analysis, which have gained importance in the international arena in recent years, in this study, the exergy energy analysis of the environment in which the sodium borohydride solution is located was performed. The best one of the Ru-based catalysts synthesized in different atomic ratios was determined as 90:10 RuCr. The surface characterization of the obtained catalyst was carried out using scanning electron microscope (SEM-EDX) and X-ray diffractometer (XRD). In the kinetic calculations, the activation energy was calculated as 35,024 kj/mol and the reaction ordered n was found to be 0,65. By applying exergy and energy analysis to the hydrogen production step, the energy and exergy efficiency of the system were found to be 24% and 7%, respectively.

Three-dimensional graphene network supported nickel-cobalt bimetallic alloy nanocatalyst for hydrogen production by hydrolysis of sodium borohydride and developing of an artificial neural network modeling to forecast hydrogen production rate

Sodium borohydride (NaBH4) is regarded as the most viable chemical for hydrogen production via hydrolysis thanks to its high theoretical hydrogen content, possible hydrogen evolution even at a low operation temperature, and producing environmentally-friendly products. However, the engineering of a high-performance catalyst is still needed to boost the kinetics of hydrolysis. Herein, nickel and cobalt decorated three-dimensional graphene (Ni-Co@3DG) nanostructure was fabricated via facile production pathway and successfully employed as the catalyst in the NaBH4 hydrolysis reaction for the first time. The influence of the different parameters, including reaction temperature, NaBH4 concentration, and catalyst loading, were examined to determine the optimum operating conditions for efficient hydrogen production. Additionally, this work differed from other works since the performance of the different artificial neural network (ANN) models were evaluated to find out the optimal ANN architecture to forecast the H2 production rate. The physicochemical characterizations offered the fabricated nanocatalyst had a large specific surface area (885 m2.g−1), and uniformly distributed Ni-Co bimetallic alloys, thereby enhancing the electrochemically active surface area for hydrolysis of NaBH4. The findings proved the superior catalytic activity of Ni-Co@ 3DG towards NaBH4 hydrolysis (initial concentration of 0.5 M) with the hydrogen production rate of 82.65 mmol.min−1.gcat at 25 ℃, and catalyst loading of 0.05 g. The reusability evaluations revealed that the Ni-Co@ 3DG catalyst could retain 95.96% of its initial activity after five successive utilizations. The computational results demonstrated that the best performance metrics were obtained for the single-layer ANN model consisting of 15 neurons in the hidden layer trained using the Bayesian Regulation backpropagation algorithm with the tansig-purelin transfer function combination in the hidden and output layers, respectively. The results demonstrated the ANN forecasted data and experimental results were in accordance, implying the optimized ANN architecture could be utilized for the prediction of the H2 production rate of the catalyst.

Hydrogen Storage in Complex Metal Hydrides NaBH4: Hydrolysis Reaction and Experimental Strategies

Worldwide, hydrogen is gaining ground since it is a promising alternative energy source to conventional fuels, which include fossil fuel. Thus, numerous techniques to generate hydrogen have been suggested. This literature review describes the challenges and obstacles identified through a series of the publications that target the hydrolysis of sodium borohydride. This review present several catalysts and reactor systems for the generation of hydrogen gas using the hydrolysis of sodium borohydride, selecting articles in the literature that show a promising future for this technology, although some challenges lie ahead. Sodium borohydride has been widely considered as a low-cost hydrogen storage material with high gravimetric hydrogen capacity of about 10 wt.%. However, its thermodynamic stability seriously hinders the application of sodium borohydride to obtain hydrogen. The performances of the reviewed systems of sodium borohydride hydrolysis include analysis from both the thermodynamic and kinetic points of view. The feasibility of an efficient hydrogen generation system, where a mixture of sodium borohydride and catalysts is hydrolyzed, is considered. This review aims to provide a useful resource to aid researchers starting work on the generation of hydrogen gas using the hydrolysis of sodium borohydride, so they can select the catalysts and reactor systems that best suit them. Thus far, no single catalyst and reactor system can simultaneously meet all of the required standards for efficient practical applications.

Polishing of zirconia ceramics by chemically-induced micro-nano bubbles

This study introduces micro-nano bubbles (MNBs) in the process of polishing zirconia ceramics through sodium borohydride hydrolysis to assist in polishing yttria-stabilized zirconia (YSZ). Compared with conventional silica sol, the material removal rate using this MNB-assisted technology is increased by 261.4%, and a lower surface roughness of 1.28 nm can be obtained. Raman, X-ray diffraction, and X-ray photoelectron spectroscopy are used to study the structural changes and phase stability of the YSZ during different polishing periods. The results show that MNBs are the key factor promoting the transformation from the tetragonal phase to the monoclinic phase on the surface of the YSZ during polishing. The H2O molecules (or OH− ions) on the surface of the YSZ are driven by the thermal kinetic energy of the micro-jets formed by the collapse of micro-bubbles, and they permeate to occupy more oxygen vacancies in the crystal lattice. Atomic force microscopy and nano-indentation tests show that the micro-protrusions on the surface of the YSZ preferentially undergo phase transformation, and their hardness decreases. This promotes abrasives to preferentially remove rough spots on the surface and achieve more efficient polishing. We believe this work adds valuable insights regarding low-temperature degradation and ultra-precise machining of YSZ ceramic materials.

Co complex modified on Eupergit C as a highly active catalyst for enhanced hydrogen production

In present paper, the preparation and catalytic activity of Eupergit C polymer (EC) modified Co complex was reported. Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD), Brunauer-Emmett-Teller Surface Area Analysis (BET), Fourier Transform Infrared Spectroscopy (FT-IR), Transmission Electron Microscopy (TEM) coupled with energy dispersive X-ray (EDX) and X-ray photoelectron spectroscopy (XPS) were used to characterization of catalyst. EC modified-Co complex was the first time examined as a catalyst in NaBH 4 hydrolysis to H 2 evolution. The kinetic calculations were determined by using two different kinetic methods. The low activation energy barriers were achieved as 21.673 kJ mol −1 for nth order model and as 21.061kJmol −1 for Langmuir-Hinshelwood (L-H) model at low temperatures. EC modified-Co complex catalyst exhibited high performance with H 2 evolution rates of 3914 mL H 2 g cat −1 min −1 and 9183 mLH 2 g cat −1 min −1 at 30 °C–50 °C. Additionally, Langmuir–Hinshelwood mechanism was explained for EC modified Co complex catalyzed sodium borohydride hydrolysis reaction. The reusability experiments showed that EC modified-Co complex catalyst maintained excellent stability with 100% conversion and without significant lost after the 6th run. • Preparation of Eupergit C polymer (EC) modified Co complex catalyst. • The first time examination of EC modified Co complex catalyst in NaBH 4 hydrolysis. • Attainment to high H 2 evolution rate of 9183mL H 2 . g cat −1 min −1 at low temperature. • Achievement of low activation energy barriers of 21.673 and 21.061;kJmol −1 . • Excellent stability without significant lost after the 6th run in NaBH 4 hydrolysis.

Facile bio-fabrication of Pd-Ag bimetallic nanoparticles and its performance in catalytic and pharmaceutical applications: Hydrogen production and in-vitro antibacterial, anticancer activities, and model development

The production of nanoparticles by the biosynthesis method attracts great attention due to their environmentally friendly structure and biocompatibility. In this study, a green method for the synthesis of Palladium-Silver nanoparticles (Pd-Ag NPs) using the extract of Nigella sativa seeds is reported. Pd-Ag NPs obtained by the green synthesis method were characterized by transmission electron microscopy (TEM), atomic force microscopy (AFM), UV–vis spectrometry, and X-Ray diffraction patterns (XRD). Pd-Ag NPs were seen to have a spherical structure in the TEM analysis image and the average particle size was found to be 6.80 nm. In addition, the anticancer and antibacterial activities of Pd-Ag NPs synthesized by the green synthesis method were investigated. Pd-Ag NPs had lethality of 69.26%, 52.28%, 76.90%, and 57.49% respectively, against Staphylococcus aureus, Methicillin-resistant Staphylococcus aureus, Bacillus subtilis, and Escherichia coli bacteria at 200 μg/mL. Besides, the antibacterial activity of Pd-Ag NPs against B. subtilis, S. aureus, and MRSA bacteria was developed by the Neuro-fuzzy (ANFIS) model. The minimum inhibitory concentration (IC50) values ​​of Pd-Ag NPs against human breast cancer cells, human endometrial carcinoma cells, and human cervical cancer cell lines were determined as 12.4384 ± 0.39 μg/mL, 13.5043 ± 0.539 μg/mL, 17.7172 ± 0.782 μg/mL, respectively. The catalytic activity of Pd-Ag NPs was investigated by sodium borohydride (NaBH4) hydrolysis. Enthalpy, entropy, turner of frequency (TOF), and activation energy values ​​were calculated as 24.51 kJ/mol, −183.15 J/mol.K, 1387.29 h−1, 27.01 kJ/mol, respectively. In the light of the obtained results, it promises that Pd-Ag NPs may play a therapeutic role in complications related to cancer and bacterial infections. The use of Pd-Ag NPs as catalysts will contribute to the development and application of new nano-catalysts to reduce environmental pollution.

Polypyrrole supported Co–W–B nanoparticles as an efficient catalyst for improved hydrogen generation from hydrolysis of sodium borohydride

Effective and reusable catalysts with high performance are essentially necessary for NaBH 4 based on-demand hydrogen generators to the widespread use for energy conversion in fuel cell power systems. Herein, we report a facile synthesis of surfactant-directed polypyrrole-supported Co–W–B nanoparticles as a robust catalyst for efficient hydrolysis of NaBH 4 reaction. This non-noble metal catalyst provides much higher catalytic activity than a conventional cobalt boride catalyst. By incorporating tungsten to catalyst composition and tuning molar ratio of W/(Co + W), about a four-fold higher hydrogen generation rate was attained compared to bare Co–B. Among the all catalysts tested, Co–W–B/PPy with 7.5% W possessed the remarkable catalytic performance of 9.92 L min −1 g −1 and high stability over five cycles with the apparent activation energy of 49.18 kJ mol −1 . • Polypyrrole supported Co–W–B catalyst was prepared by reduction - precipitation route. • Hydrogen generation rate was highly improved by adding tungsten to the catalyst composition. • The catalyst with optimized composition showed the hydrogen generation rate of 9.92 L min −1 g −1 . • The catalyst was retained durability after five cycles.

Efficient Hydrolytic Hydrogen Evolution from Sodium Borohydride Catalyzed by Polymer Immobilized Ionic Liquid‐Stabilized Platinum Nanoparticles

AbstractPlatinum nanoparticles stabilized by imidazolium‐based phosphine‐decorated Polymer Immobilized Ionic Liquids (PPh2‐PIIL) catalyze the hydrolytic evolution of hydrogen from sodium borohydride with remarkable efficiency, under mild conditions. The composition of the polymer influences efficiency with the catalyst based on a polyethylene glycol modified imidazolium monomer (PtNP@PPh2‐PEGPIILS) more active than its N‐alkylated counterpart (PtNP@PPh2‐N‐decylPIILS). The maximum initial TOF of 169 moleH2.molcat−1.min−1 obtained at 30 °C with a catalyst loading of 0.08 mol% is among the highest to be reported for the aqueous phase hydrolysis of sodium borohydride catalyzed by a PtNP‐based system. Kinetic studies revealed that the apparent activation energy (Ea) of 23.9 kJ mol−1 for the hydrolysis of NaBH4 catalyzed by PtNP@PPh2‐PEGPIILS is significantly lower than that of 35.6 kJ mol−1 for PtNP@PPh2‐N‐decylPIILS. Primary kinetic isotope effects kH/kD of 1.8 and 2.1 obtained with PtNP@PPh2‐PEGPIILS and PtNP@PPh2‐N‐decylPIILS, respectively, for the hydrolysis with D2O support a mechanism involving rate determining oxidative addition or σ‐bond metathesis of the O−H bond. Catalyst stability and reuse studies showed that PtNP@PPh2‐PEGPIILS retained 70 % of its activity across five runs; the gradual drop in conversion appears to be due to poisoning of the catalyst by the accumulated metaborate product as well as the increased viscosity of the reaction mixture.

Highly active PdPt bimetallic nanoparticles synthesized by one-step bioreduction method: Characterizations, anticancer, antibacterial activities and evaluation of their catalytic effect for hydrogen generation

Metallic nanoparticles (MNPs) have important applications in medicine and technology. Bimetallic NPs, which are among the metallic nanoparticles, are of great interest due to their properties. An innovative method by green synthesis has been developed to obtain bimetallic NPs. Aromatic plants are used in this synthesis method. One of the plants used for green synthesis is Nigella sativa and it has a unique place among plants for use as medicine. In this study, the synthesis of Palladium–Platinum bimetallic nanoparticles (PdPt NPs) and the catalytic, antibacterial, and anticancer activity of synthesized PdPt NPs by green synthesis method using Nigella sativa seed extract are reported. The synthesized PdPt NPs were characterized by Fourier Transform Infrared Spectrophotometer (FTIR), Transmission Electron Microscopy (TEM), X-ray diffraction (XRD), and UV–Vis spectrometry techniques. The catalytic activity of PdPt NPs was determined by performing sodium borohydride (NaBH4) hydrolysis experiments. According to the results obtained, Turnover Frequency (TOF), activation energy, entropy, and enthalpy values were found to be 1664.76 h−1, 13.93 kJ/mol, −119.02 J/mol.K, and 11.43 kJ/mol, respectively. It was determined that PdPt NPs are highly effective catalysts for hydrogen production. PdPt NPs (200 μg/mL) were determined to have antibacterial activity of 57.58%, 64.42%, 48.68%, and 58.77% against Escherichia coli, Staphylococcus aureus, Methicillin-resistant Staphylococcus aureus, and Bacillus subtilis bacteria, respectively. In addition, the cytotoxic effects of PdPt NPs, MTT against human breast cancer cell line (MDA-MB-231), human endometrial carcinoma cell line (Ishikawa, ISH), human cervical cancer cell line (HeLa), L929-Murine fibroblast cell line test, and IC50 values were calculated. The IC50 values of PdPt NPs applied against MDA-MB-231, ISH, and HeLa cancer cell lines were calculated as 9.1744 ± 1.566 μg/mL, 12.2431 ± 1.132 μg/mL, 18.1963 ± 1.730 μg/mL, respectively. No significant cytotoxic effect was observed in healthy L929-murine fibroblasts. Green synthesis of PdPt NPs was determined to have significant advantages over chemical approaches. The biogenic PdPt NPs synthesized in this study suggest the design of bio-based bimetallic catalysts with high catalytic performance to prevent environmental pollution.

Magnetically recyclable Co2P nanosheets as highly efficient catalysts for hydrogen generation from hydrolysis of sodium borohydride

A facile strategy was developed for the preparation of magnetically recyclable Co2P nanosheets with efficient catalytic activity for NaBH4 hydrolysis.