Alkaline NaBH4 Research Articles

Enhancing the activity of Ni-B catalyst via Cu doping towards hydrogen evolution from NaBH4 hydrolysis

Developing efficient, economical, and eco-friendly catalysts for hydrogen release from hydrogen storage materials such as sodium borohydride (NaBH4) is recognized as an ideal solution to meet the growing demand for clean energy. In the present study the Ni-Cux-B alloy catalysts with different Cu doping content on the corncob (CC) substrate via a facile electroless plating method for the hydrolysis of NaBH4 were synthesized. The structural and morphological characteristics of the synthesized catalysts were investigated using various analytical techniques. The results showed that an appropriate Cu content has a remarkable excitation effect on the catalytic activity of Ni-B. The Cu doping strategy effectively changes the dispersion of metal species and provides more catalytic active sites on the surface of the catalyst. Moreover, the synergistic effect between metals after Cu doping enhances electron transfer and facilitates the adsorption and activation of BH4 and H2O molecules, thereby promoting hydrogen production activity. The optimized Ni-Cu7.2-B catalyst achieved a hydrogen generation rate (HGR) of 1321.56 mL min−1 g−1 in alkaline NaBH4 solution at 303 K, with an activation energy (Ea) of 46.26 kJ mol⁻1. The Ni-Cu7.2-B catalyst exhibits satisfactory stability, retaining 90.8 % of its initial catalytic activity after five cycles.

Hydrogen generation by hydrolysis of alkaline NaBH4 solution doped with amorphous catalyst Co–Y2O3–B/CNTs

This investigation enhances the catalytic efficiency of Co–B/CNTs for hydrogen production via sodium borohydride hydrolysis by doping with 5%Y2O3. Such doping significantly boosts hydrogen evolution rates, with Co–Y2O3–B/CNTs achieving a production rate of 1083.43 ml g−1·min−1—surpassing Co–B/CNTs by 1.5 times and tripling that of Co–B catalysts. SEM and XRD analyses show Y2O3 doping reduces particle aggregation and maintains the catalyst's amorphous state, thereby increasing the active surface area. Furthermore, XPS analysis demonstrates that introducing yttrium into Co–B/CNTs catalysts improves their surface elemental composition and valence states. This improvement boosts catalyst performance and stability by enhancing electron transfer and particle size optimization. Optimal hydrolysis is achieved at an NaOH concentration of 2.5 mol/L, with higher concentrations diminishing hydrogen production due to increased viscosity from by-product formation. Additionally, Co–Y2O3–B/CNTs catalysts exhibit commendable durability, maintaining more than two-thirds of their initial activity after five reuse cycles, outperforming comparable catalysts to a moderate extent. These findings underscore the beneficial role of Y2O3 in the Co–B/CNTs framework, promoting Y2O3-doped catalysts for their enhanced efficiency, sustainability, and hydrogen production capabilities.

Ni–CoP catalyst for efficient and robust NaBH4 hydrolysis

Hydrogen fuel is a non-toxic and source-abundant energetic system, but for its applications in the industry, several issues related to its storage must be resolved. Compounds like NaBH4 appear as promising hydrogen sources, while can release the latter rapidly under controllable conditions with the use of heterogeneous catalyst systems. In this work, we synthesized a Ni–CoP catalyst by electrodeposition in a three-step process on carbon paper as support. The materials were characterized via SEM-EDS, XRD, and XPS techniques, while the hydrogen evolution reaction (HER) from alkaline NaBH4 solutions was tested as a batch experiment. Ni–CoP catalyst showed a high amount of H2 generated in a short time (∼550 mL in 1 min) and remained at 78 and 54% of its initial performance after respectively 100 and 300 h of a continuous hydrolysis process. Our catalyst revealed exceptional performance and stability at higher temperatures and a long process time, which have been a rare subject of investigation in other reports for NaBH4 hydrolysis in the past. This work paves a new perspective in studying catalysts for hydrogen generation from borohydrides.

Au-Based MOFs as Anodic Electrocatalysts for Direct Borohydride Fuel Cells

Researchers are exploring direct liquid fuel cells (DLFCs) as alternatives to proton-exchange membrane fuel cells because of their higher energy density and ease of storing and transporting the fuel. Direct borohydride fuel cells (DBFCs) are of particular interest as they offer a sustainable energy source with their high-power density output and the use of a highly alkaline NaBH4 medium [1]. Ensuring efficient and cost-effective catalysts for DBFCs is crucial for their commercial viability. Metal-organic frameworks (MOFs) have demonstrated significant potential as anodic electrocatalysts for BOR in DBFCs [2]. However, research should explore various modifications to MOFs, such as the incorporation of alternative metal ions or functional groups, to improve their catalytic efficiency and reduce cost. This study evaluated the performance of newly developed MOF-based electrocatalysts for DBFCs. Specifically, six MOF-based materials were synthesized and analyzed for their ability to facilitate borohydride oxidation (BOR) using cyclic voltammetry and chronoamperometry in alkaline media. MIL-101_Au@NH2 and MOF-808_Au@NH2 were found to be highly effective for BOR. The kinetic parameters for BOR with MOF-based electrocatalysts, including activation energy, reaction order, exchanged electrons, and anodic charge transfer coefficient, were determined. The activation energy for BOR was found to be 13.6 kJ mol−1 and 15.3 kJ mol−1 for MIL-101_Au@NH2 and MOF-808_Au@NH2, respectively. The number of transferred electrons, n, was found to be 7.0 and 3.1 for MIL-101_Au@NH2 and MOF-808_Au@NH2, respectively. This study demonstrates that MOF-based electrocatalysts can enhance DBFCs' performance, while offering insight into the potential usage of MOFs in other fuel cell technologies.[1] B. Šljukić, D.M.F. Santos, "Direct borohydride fuel cells", in: "Direct Liquid Fuel Cells: Fundamentals, Advances, and Future", 1st ed., R.G. Akay, A.B. Yurtcan (eds.), Academic Press, USA, 203-232 (2021)[2] G. Backovic, B. Šljukić, G.S. Kanberoglu, M. Yurderi, A. Bulut, M. Zahmakiran, D.M.F. Santos, Ruthenium (0) nanoparticles stabilized by the metal-organic framework as an efficient electrocatalyst for borohydride oxidation reaction, International Journal of Hydrogen Energy, 45, 27056-27066 (2020).

Bipolar Membranes for Direct Borohydride Fuel Cells-A Review.

Direct liquid fuel cells (DLFCs) operate directly on liquid fuel instead of hydrogen, as in proton-exchange membrane fuel cells. DLFCs have the advantages of higher energy densities and fewer issues with the transportation and storage of their fuels compared with compressed hydrogen and are adapted to mobile applications. Among DLFCs, the direct borohydride-hydrogen peroxide fuel cell (DBPFC) is one of the most promising liquid fuel cell technologies. DBPFCs are fed sodium borohydride (NaBH4) as the fuel and hydrogen peroxide (H2O2) as the oxidant. Introducing H2O2 as the oxidant brings further advantages to DBPFC regarding higher theoretical cell voltage (3.01 V) than typical direct borohydride fuel cells operating on oxygen (1.64 V). The present review examines different membrane types for use in borohydride fuel cells, particularly emphasizing the importance of using bipolar membranes (BPMs). The combination of a cation-exchange membrane (CEM) and anion-exchange membrane (AEM) in the structure of BPMs makes them ideal for DBPFCs. BPMs maintain the required pH gradient between the alkaline NaBH4 anolyte and the acidic H2O2 catholyte, efficiently preventing the crossover of the involved species. This review highlights the vast potential application of BPMs and the need for ongoing research and development in DBPFCs. This will allow for fully realizing the significance of BPMs and their potential application, as there is still not enough published research in the field.

Atomically precise Au nanocluster-embedded carrageenan for single near-infrared light-triggered photothermal and photodynamic antibacterial therapy

In this study, we report atomically precise gold nanoclusters-embedded natural polysaccharide carrageenan as a novel hydrogel platform for single near-infrared light-triggered photothermal (PTT) and photodynamic (PDT) antibacterial therapy. Briefly, atomically precise captopril-capped Au nanoclusters (Au25Capt18) prepared by an alkaline NaBH4 reduction method and then embedded them into the biosafe carrageenan to achieve superior PTT and PDT dual-mode antibacterial effect. In this platform, the embedded Au25Capt18, as simple-component phototherapeutic agents, exhibit superior thermal effects and singlet oxygen generation under a single near-infrared (NIR, 808 nm) light irradiation, which enables rapid elimination of bacteria. Carrageenan endows the hydrogel platform with superior gelation characteristics and wound microenvironmental regulation. The Au25Capt18-embedded hydrogels exhibited good water retention, hemostasis, and breathability, providing a favorable niche environment for promoting wound healing. In vitro experiments confirmed the excellent antibacterial activity of the Au25Capt18 hydrogels against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli. The antibacterial effect and promoting wound healing function were further validated in a S. aureus-infected wound model. Biosafety evaluation showed that the Au25Capt18 hydrogel has excellent biocompatibility. This PTT/PDT dual-mode therapy offers an alternative strategy for battling bacterial infections without antibiotics. More importantly, this hydrogel is facile to prepare which is helpful for expanding applications.

Oxygen-vacancy-rich Ru-clusters decorated Co/Ce oxides modifying ZIF-67 nanocubes as a high-efficient catalyst for NaBH4 hydrolysis

Designing a cost-effective and high-performance catalyst for NaBH4 hydrolysis is a significant step in developing a sustainable hydrogen source. Herein, we prepared a cost-effective Ru-clusters decorated cobalt-cerium oxides coating ZIF-67 (Ru/Co6Ce1@ZIF-67) catalyst via a facile reduction method, displaying high performance and exceptional reusability in alkaline NaBH4 solution. The optimized catalyst exhibits a high hydrogen generation rate (HGR, 5726.1 mL min−1 g−1), turnover frequency (TOF, 413.9 molH2 min−1molRu−1), and low activation energy (Ea, 53.0 kJ mol−1), surpassing most of the recently reported catalysts. Furthermore, the catalytic performance does not change considerably after five cycles, indicating the catalyst's multi-cycle reusability. Studies imply the uniquely synergistic effect of Ru, Co/Ce oxides, abundant oxygen vacancies, as well as the porous nanocube structure, enabling the catalysts to possess high metal dispersion, outstanding catalytic performance and exceptional reusability. This work will open light on using an oxygen vacancies-rich strategy to design a high-activity catalyst for promoting NaBH4 hydrolysis.

3D Structured Pt(Cu-Ni)/Ti Catalysts for the Oxidation of Sodium Borohydride

Currently, one of the renewable energy sources is fuel cells, namely chemical energy is directly converted into electricity. Designing new or enhancing the existing fuel cells, much attention is devoted to the search of new effective catalysts, which would allow increasing the effectiveness of fuel cells and creating the background for designing new technologies for catalysts formation.The aim of the work is to form efficient and inexpensive nanostructured catalysts by electroplating 3D structure metal copper-nickel (Cu-Ni) foams on titanium (Ti) surface and decorating them with low amounts of platinum nanoparticles (PtNP) for the electrooxidation of sodium borohydride (NaBH4). The Cu-Ni foam was prepared by electrochemical deposition (I deposition=1.5 Acm-2, t deposition= 3,6 and 9 min) on Ti surface. The electrolyte contained 0.5 M Ni2+ ions, and the concentrations of Cu2+ ions ranged from 0.01 to 0.02 M.PtNP particles were deposited on Cu-Ni foam (noted (Pt(Cu-Ni)/Ti)) by immersion of Cu-Ni foam into 1 mM H2PtCl6 solution at 25 °C for 1 minute. The morphology and composition of the prepared catalysts were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), and inductively coupled plasma optical emission spectroscopy (ICP-OES). The electrocatalytic activity of the 3D catalysts was evaluated towards the oxidation of borohydride by cyclic voltammetry method in 0.05 M NaBH4 solution in an alkaline media in the potential range from -1.2 to 0.6 V (vs. Ag/AgCl) and with an electrode potential scan rate of 10 mVs-1.The study showed that the prepared 3D Cu-Ni foam and Pt(Cu-Ni)/Ti have good electrochemical stability in alkaline NaBH4 solution. It was also observed that immersion of Cu-Ni foam in a platinum-containing solution for 1 min increased the electrocatalytic activity of the prepared Pt(Cu-Ni)/Ti catalysts for NaBH4 oxidation compared to Cu-Ni foam. Acknowledgment This project has received funding from European Social Fund (project No 09.3.3-LMT-K-712-19-0138) under a grant agreement with the Research Council of Lithuania (LMTLT).

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.

Surface tailored Ru catalyst on magadiite for efficient hydrogen generation

In the present study, a uniformly dispersed, highly durable and efficient ruthenium (Ru) catalyst for hydrogen production was successfully prepared by a facile template method induced by surface-tailored magadiite. The catalyst was systematically characterized and the results revealed that the uniformly dispersed Ru particles with showing an average size of 1.2 nm preferred to anchor on the surface of magadiite, rather than intercalated into the support. Catalytic activity and reutilization of the catalysts were evaluated by evaluating the H2 generation rate (HGR) from an alkaline NaBH4 solution. The maximum HGR at 25 °C reached 59276 ± 500 mL·min−1·g−1 (Ru) with the presence of 3 wt% NaOH and 1 wt% NaBH4. More importantly, the catalytic activity of the reused catalyst still remained 95.7% of the initial HGR after 20 runs. Thus, the catalyst shows high durability and excellent reutilization towards the hydrolysis of alkaline NaBH4 solution. The uniform decoration of Ru particles on magaditte surface is responsible for the high efficiency of the catalyst. This work has revealed that tailoring the distribution of Ru particles on magadiite surface via a simple template method is a promising route for fabricating high-performance hydrogen production catalysts.

Recent Advances in Applications of Co-B Catalysts in NaBH4-Based Portable Hydrogen Generators

This review highlights the opportunities of catalytic hydrolysis of NaBH4 with the use of inexpensive and active Co-B catalysts among the other systems of hydrogen storage and generation based on water reactive materials. This process is important for the creation of H2 generators required for the operation of portable compact power devices based on low-temperature proton exchange membrane fuel cells (LT PEM FC). Special attention is paid to the influence of the reaction medium on the formation of active state of Co-B catalysts and the problem of their deactivation in NaBH4 solution stabilized by alkali. The novelty of this review consists in the discussion of basic designs of hydrogen generators based on NaBH4 hydrolysis using cobalt catalysts and the challenges of their integration with LT PEM FC. The potential of using batch reactors in which there is no need to use aggressive alkaline NaBH4 solutions is discussed. Solid-phase compositions or pellets based on NaBH4 and cobalt-containing catalytic additives are proposed, the hydrogen generation from which starts immediately after the addition of water. The review made it possible to formulate the most acute problems, which require new sci-tech solutions.

Hydrogen Generation from an Alkaline NaBH4 Solution Using Different Cobalt Catalysts

The effective Co, CoB and CoBM, where M = Mo, Zn, and Fe, catalysts have been deposited on the Cu surface by a simple electroless metal deposition method using morpholine borane as a reducing agent and used as catalysts for hydrogen generation from an alkaline NaBH4 solution. The catalytic activity of different cobalt alloys catalysts towards the hydrolysis of NaBH4 has been investigated by measuring the amount of generated hydrogen from an alkaline solution contained 5 wt. % NaBH4 and 0.4 wt. % NaOH. The rate of H2 generation has been measured at solution temperatures in the range from 298 to 318 K in order to determine the activation energy.It has been determined that the synthesized Co/Cu, CoB/Cu and CoBM (M=Mo,Zn,Fe)/Cu catalysts demonstrate the catalytic activity for the hydrolysis reaction of NaBH4. The lowest obtained activation energy of the hydrolysis reaction of NaBH4 has been 27 kJ mol-1 for the CoBMo/Cu catalyst. The hydrogen generation rate has been achieved 15.30 ml min-1 using the CoBMo/Cu catalyst at a temperature of 313 K and it increases ~3.5 times with the increase of temperature to 343 K. Moreover, the CoBMo/Cu catalyst shows a highest catalytic activity for hydrogen generation from the alkaline NaBH4 solution as compared with that for other Co/Cu, CoB/Cu, CoBZn/Cu, and CoBFe/Cu catalysts.

HYDROGEN GENERATION FROM SODIUM BOROHYDRIDE WITH COBALT BORIDE CATALYSTS

NaBH4 is a promising hydrogen storage material, with its high hydrogen storage capacity (10.8 wt%), stability in alkaline solutions, mild reaction temperature, nontoxic by products and controllable hydrogen generation rates. Hydrogen generation of NaBH4 was investigated with Co2B/TiO2 composite catalyst. Co catalysts are very good candidates for NaBH4 hydrolysis from economical viewpoint. Composite catalysts have attracted continuous interest during the past decades and enable to give high selectivity, high activity and good stability. In this study, 1:1, 1:2, 1:3 and 1:4 molar ratio of Co2B/TiO2 composite catalysts were prepared to study hydrogen generation effects. Firstly, Co2B was produced with NaBH4 and CoCl2. Then, Co2B and TiO2 were mixed and grinded in a planetary ball mill. A 250 ml flask (with two openings, placed in a water bath) was used for the experiment. Alkaline NaBH4 solution and prepared catalysts were used and hydrogen generation rate was measured with the adjusted inverted burette which was submerged to the water at room temperature. 1:3 mole ratio composite catalysts gave the highest hydrogen generation rate as 364.58 ml.g-1.min-1 with 0.3 g catalyst amount, 2 wt% NaOH concentration, 9 wt% NaBH4 concentration and at 35 ○C. The effects of catalyst amount, NaOH and NaBH4 compositions, reaction temperature on the hydrogen generation rate were investigated and kinetic rate expression was determined. The calculated activation energy was 36.50 kJ.mol-1 , this value is low when compared to previous studies. These composite catalysts introduced perfect catalytic properties and can undertake the applications in hydrogen generation and hydrogen storage.

A study on hydrogen generation from NaBH4 solution using Co-loaded resin catalysts

Hydrogen production via chemical processes has gained great attention in recent years. In this study, Co-based complex catalyst obtained by adsorption of Co metal to Amberlite IRC-748 resin and Diaion CR11 were tested for hydrogen production from alkaline NaBH4 via hydrolysis process. Their catalytic activity and microstructure were investigated. Process parameters affecting the catalytic activity, such as NaOH concentration, Co percentage and catalyst amount, as well as NaBH4 concentration and temperature were investigated. Furthermore, characteristics of these catalysts were carried out via SEM, XRD and FT-IR analysis. Hydrogen production rates equal to 211 and 221 ml min−1 gcat−1 could be obtained with Amberlite IRC-748 resin and Diaion CR11 Co based complex catalysts, respectively. The activation energies of the catalytic hydrolysis reaction of NaBH4 were calculated as 46.9 and 59.42 kJ mol−1 for Amberlite IRC-748 resin and Diaion CR11 based catalysts respectively kJ mol−1 from the system consisting of 3% Co, 10 wt% NaBH4 and 7 wt% NaOH as well as 50 mg catalyst dosage. It can be concluded that Co-based resins as catalysts for hydrogen production is an effective alternative to other catalysts having higher rate.

Oxygen vacancies engineered self-supported B doped Co3O4 nanowires as an efficient multifunctional catalyst for electrochemical water splitting and hydrolysis of sodium borohydride

Developing earth abundant electrocatalyst is imperative to large-scale hydrogen production for transforming current fossil fuel-based economy into future renewable energy economy. In this paper, we report the synthesis of self-supported VOB-Co3O4/NF nanowire arrays directly grown on Ni foam, which can serve as a trifunctional catalyst for producing hydrogen and oxygen by electrolyzing water in alkaline media or producing hydrogen via hydrolyzing alkaline NaBH4 solution. The engineered boron and oxygen defects in Co3O4 nanowires prove to effectively modulate their electronic structure leading to the increased electrical conductivity and create a large quantity of electroactive sites. The resulting self-supported VOB-Co3O4/NF electrode delivers a current density of 50 mA cm−2 at overpotentials of 184 mV for hydrogen evolution reaction (HER) and 315 mV for oxygen evolution reaction (OER) in 1.0 M KOH with excellent stability and durability. The VOB-Co3O4/NF as both cathode and anode requires 1.67 V to achieve a current density of 10 mA cm−2 for overall water splitting reaction. Besides, VOB-Co3O4/NF presents much higher hydrogen generation rate (HGR) of 7055 mL min−1 gcatalyst−1 with activation energy (Ea) of ca. 29.7 kJ mol−1. for hydrolytic dehydrogenation of alkaline NaBH4 solution, outperforming most of the reported non-noble metal-based catalysts and even precious metal catalysts.

Hydrogen Generation from Hydrolysis of Sodium Borohydride Using Nanosized NiB Amorphous Alloy Catalysts

Generation of hydrogen by sodium borohydride solution had attracted lots of attention. A serial of nanosized NiB catalysts were prepared using the chemical reduction method through introducing AlCl3 into the preparation. Catalytic performance of NiB catalysts were investigated in the hydrolysis of alkaline NaBH4 solution. The catalysts were characterized by X-ray diffraction (XRD), N2 adsorption, Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The results showed that NiB catalysts possessed amorphous alloy structure, and the particle size could be adjusted by the AlCl3 amount. Catalytic performance showed that NiB catalyst with smaller particle size had much higher activity. The NiB catalyst also displayed high stability, the catalytic activity could retain about 84% of its initial value after four cycles.

Influence of Water Transport Across Microscale Bipolar Interfaces on the Performance of Direct Borohydride Fuel Cells

Direct borohydride fuel cells (DBFCs) can operate at double the voltage of proton exchange membrane fuel cells (PEMFCs) by employing an alkaline NaBH4 fuel feed and an acidic H2O2 oxidant feed. The pH-gradient-enabled microscale bipolar interface (PMBI) facilitates the creation and maintenance of an alkaline environment at the anode and an acidic environment at the cathode for the borohydride oxidation and peroxide reduction reactions. However, given the need to dissociate water at the interface to ensure ionic conduction, PMBI can be efficient only when anion exchange ionomer (AEI) moieties enable fast water transport for autoprotolysis. Herein, a series of polynorbornene-based AEIs with a range of water uptake values are examined to unravel the optimum water uptake required to enable high performance DBFCs. The DBFC with PMBI configuration containing the optimal AEI composition delivers a current density of 302 mA cm–2 at 1.5 V and a peak power density of 580 mW cm–2 at 1 V. This AEI composition exhibits high hydroxide ionic conductivity of 90.7 mS cm–1 at 80 °C with an IEC of 2.01 mequiv g–1 and demonstrates impressive chemical stability by retaining 98.75% of its initial ionic conductivity after immersion into anolyte (3 M KOH and 1.5 M NaBH4) at 70 °C for 536 h.

Cobalt–copper–boron nanoparticles as catalysts for the efficient hydrolysis of alkaline sodium borohydride solution

Developing non-precious metal catalysts with high activity is crucial for the extensive applications of the proton exchange membrane fuel cell (PEMFC). Herein, we have prepared cobalt–copper–boron (Co–Cu–B) nanoparticles by a modified chemical reduction route where Ni foam was used as an initiation medium for the efficient hydrolysis of alkaline sodium borohydride (NaBH4) solution. The influence of the synthetic condition (such as Cu2+ concentration, pH value and the concentration of reducing agent) on the catalytic activities has been explored. The catalytic hydrolytic tests reveal that the as-obtained Co–Cu–B nanoparticles with hollow spherical structure shows highly efficient catalytic activity, affording a hydrogen generation rate (HGR) of 3554.2 mLH2·gcatal.−1·min−1 under room temperature, and a lower activation energy of 52.0 kJ· mol−1, which overtakes the activities of previous reported most non-precious metal catalysts, even some precious catalysts. The kinetics results show that the catalytic hydrolysis process of alkaline NaBH4 solution is a zero-order reaction in view of the amount of Co–Cu–B catalyst, meaning that the reaction rate is independent of the catalyst amount. This study offers us a promising non-precious metal catalyst toward dehydrogenation from the hydrolysis of NaBH4 to further speed up the application steps.

Hydrogen production through the cooperation of a catalyst synthesized in ethanol medium and the effect of the plasma

ABSTRACT In the present study, nanostructured Ni-B catalysts were successfully prepared in ethanol medium using the chemical reduction method for hydrogen production from the catalytic hydrolysis of sodium borohydride (NaBH4). Ni-B nanostructures were characterized by several analysis methods including XRD, SEM/EDS, FT-IR and BET. The effects of factors such as solution temperature, NaBH4 loadings, catalyst amount and NaOH concentration on the performance of these catalysts in the production of hydrogen from alkaline NaBH4 solutions were investigated in detail. In addition, the Ni-B catalyst prepared in ethanol medium and subjected to plasma for the hydrogen production from the catalytic hydrolysis of NaBH4 was investigated. The Ni-B catalyst prepared in ethanol medium showed maximum hydrogen production rate (1000 mL min−1gcatalyst−1) which was approximately 2 times higher than the rate obtained from the Ni-B catalyst prepared in water (400 mL min−1gcatalyst−1) and acethone (550 mL min−1gcatalyst−1). The Ni-B nanoparticles showed the best catalytic activity at 333 K with a maximum hydrogen production rate of 7134 mL min−1gcatalyst−1 and activation energy of 46.83 kJmol−1 for the NaBH4 hydrolysis reaction in the Ni-B catalysts prepared in ethanol and subjected to plasma. As the Ni-B catalyst is inexpensive and easy to prepare, it is feasible to use this catalyst in the construction of practical fuel cells for portable and in situ applications.

Pitaya pulp structural cobalt–carbon composite for efficient hydrogen generation from borohydride hydrolysis

The design and synthesis of high efficiency catalysts for hydrogen generation and storage are the key factors for large-scale hydrogen use. Herein, a Pitaya pulp structural cobalt-based carbon nanocatalyst is synthesized. The 5–10 nm Co/CoOx particles are uniformly distributed in the 500-nm spherical carbon matrix and enable efficient catalytic performance during hydrogen generation from the alkaline NaBH4 and NH3BH3 solutions at 3998 mL min−1·gCo−1 for NaBH4 and 4677 mL min−1·gCo−1 for NH3BH3. The catalyst nanoparticles were prepared by a facile one-pot solution reaction, pyrolysis at high temperature, and oxidation in air. The coexistence of various valence states of Co in the composite material is observed by utilizing various characterization methods. Co nanoparticles fixed in the carbon matrix effectively prevent particles from aggregation and loss. This unique structure's similarity with Pitaya pulp, its synergistic effects, and its self-stirring mode enable its effective catalytic performance and good stability. The results provide a reference direction for the design and synthesis of unique structure catalysts for efficient hydrogen production.