Sodium Borohydride In Aqueous Solution Research Articles

Nanotitania supported ruthenium(0) nanoparticles as active catalyst for releasing hydrogen from dimethylamine borane

We reports the ex situ preparation of nanotitania supported ruthenium(0) nanoparticles (NPs) and their catalytic testing in dehydrogenation of dimethylamine borane (DMAB) in toluene solvent. Ru0/TiO2 NPs are prepared following a 2-step process: Ru3+ ions are first impregnated from the aqueous solution on titania nanopowder and then, reduced by aqueous solution of sodium borohydride. The prepared Ru0/TiO2 NPs are dried, bottled under inert N2 gas atmosphere, and used for characterization by XRD (X-ray powder diffraction), TEM (transmission electron microscopy), ICP-OES (inductively coupled plasma optical emission spectroscopy) and XPS (X-ray photoelectron spectroscopy). Ru0/TiO2 NPs with various Ru loadings are tested as catalysts in hydrogen generation from DMAB and the Ru0/TiO2 (0.48% wt. Ru) with an average diameter of 6.7 ± 1.3 nm is found to have the highest initial turnover frequency value of 1700 h−1 for the release of 1.0 mol H2 per mole of DMAB at 60 °C. Results of the recyclability test indicate quite high durability of Ru0/TiO2 NPs in dehydrogenation of DMAB.

Bifunctional Polymer Brush Reactor for In Situ Synthesis of Hollow Silica-Supported Gold Nanocatalysts.

Gold nanoparticles (AuNPs) on carriers have received wide attention as catalysts as a result of their excellent stability and catalytic performance. Herein, we report the design and synthesis of hollow silica-supported gold nanocatalysts (SNPs@AuNPs) composed of highly dispersed AuNPs with approximately 4.30 nm using an in situ colloidal polyelectrolyte template strategy. The monodisperse polystyrene nanospheres accompanied by poly[(2-methacryloyloxyethyl)trimethylammonium chloride] brushes were first synthesized. Subsequently, the facile polymer-brush-engaged strategy for the synthesis of hollow SNPs@AuNPs involves in situ reduction of AuNPs, hydrolytic condensation of silica, and a chemical etching process. In combination with dynamic light scattering, transmission electron microscopy, small-angle X-ray scattering, X-ray powder diffraction, and Fourier transform infrared spectroscopy, the as-obtained polymer brushes were proven as effective versatile nanoreactors for the synthesis of AuNPs and silica nanoparticles without any catalysts. Benefiting from the structural advantages, the resultant hollow SNPs@AuNPs manifested superior catalytic activity and reusability for the reduction of p-nitrophenol by sodium borohydride in aqueous solution. With a delicate design, we believe that this synthetic strategy can be extended to fabricate multifunctional nanomaterials with diverse compositions, which would be of great interest in catalysis, energy, and many other important domains.

A new two-dimensional luminescent Ag12 cluster-assembled material and its catalytic activity for reduction of hexacyanoferrate(III).

Silver cluster-assembled materials (SCAMs) have garnered significant interest as promising platforms for different functional explorations. Their atomically precise structures, intriguing chemical/physical properties, and remarkable luminescent capabilities make them highly appealing. However, the properties of these materials are primarily determined by their structural architecture, which is heavily influenced by the linker molecules used in their assembly. The choice of linker molecules plays a pivotal role in shaping the structural characteristics and ultimately determining the unique properties of SCAMs. To this end, the first SCAM with an intriguing (3,6)-connected kgd topology, [Ag12(StBu)6(CF3COO)6(TPBTC)6]n (termed TUS 3), TPBTC = benzene-1,3,5-tricarboxylic acid tris-pyridin-4-ylamide, has been synthesized by reticulating C6-symmetric Ag12 cluster cores with C3-symmetric tripodal pyridine linkers. Due to the structutural architecture of the linker molecule, TUS 3 posseses a luminescent porous framework structure where each two-dimensional (2D) layers are non-covalently linked with each other to form a three dimensional (3D) framework and ultimately offers uniaxial open channels. The compact mesoporous structural architecture not only gives the excellent surface area but also offers impressive stability of this material even in water medium. Taking advantage of these properties, TUS 3 shows brilliant catalytic activity in the reduction of hexacyanoferrate(III) using sodium borohydride in aqueous solutions.

Xanthan gum mediated monowave synthesis of silver nanoparticles: Characterization, anticancer, antimicrobial, antioxidant and catalytic studies

Using a monowave approach, stabilized silver nanoparticles (AgNPs) were synthesized by xanthan gum as a reducing agent. The combination of XG and AgNPs is a cost-effective and environmentally friendly method of synthesis. The effects of various parameters, such as time and concentrations of silver nitrate and xanthan gum, on the formation of AgNPs were also studied. The synthesized AgNPs were analyzed using UV–Vis spectrophotometry, FTIR, X-ray diffractometry, and TEM measurements, revealing the characteristic SPR band for Ag at 420 nm. TEM images indicated that over 70% of the AgNPs were below 10 nm in size. Green-synthesized AgNPs exhibited significant anticancer activity against MCF-7 cells, outperforming Doxorubicin. Antibacterial studies showed that AgNPs possess inhibitory properties against both gram-positive and gram-negative bacteria. The antioxidant activity of AgNPs was evaluated using DPPH assay, and IC50 values of 40.2 µg/mL and 43.4 µg/mL were obtained, indicating significant free radical scavenging activity. Finally, the catalytic activity of AgNPs was studied with respect to the reduction of hexacyanoferrate (III) by sodium borohydride in aqueous solution. These AgNPs exhibited good catalytic activity, and the kinetics of the reaction were found to be pseudo first order with respect to the hexacyanoferrate (III).

A facile one-stone-two-birds strategy for fabricating multifunctional 3D nanofibrous scaffolds.

Local bacterial infections lead to delayed wound healing and in extreme cases, such as diabetic foot ulcers, to non-healing due to the impaired cellular function in such wounds. Thus, many scientists have focused on developing advanced therapeutic platforms to treat infections and promote cellular proliferation and angiogenesis. This study presents a facile approach for designing nanofibrous scaffolds in three dimensions (3D) with enhanced antibacterial activity to meet the need of treating chronic diabetic wounds. Being a cationic surfactant as well as an antimicrobial agent, octenidine (OCT) makes a 2D membrane hydrophilic, enabling it to be modified into a 3D scaffold in a "one stone, two birds" manner. Aqueous sodium borohydride (NaBH4) solution plays a dual role in the fabrication process, functioning as both a reducing agent for the in situ synthesis of silver nanoparticles (Ag NPs) anchored on the nanofiber surface and a hydrogen gas producer for expanding the 2D membranes into fully formed 3D nanofiber scaffolds, as demonstrated by morphological analyses. Various techniques were used to characterize the developed scaffold (e.g., SEM, XRD, DSC, FTIR, and surface wettability), demonstrating a multilayered porous structure and superhydrophilic properties besides showing sustained and prolonged release of OCT (61% ± 1.97 in 144 h). Thanks to the synergistic effect of OCT and Ag NPs, the antibacterial performance of the 3D scaffold was significantly higher than that of the 2D membrane. Moreover, cell viability was studied in vitro on mouse fibroblasts L929, and the noncytotoxic character of the 3D scaffold was confirmed. Overall, it is shown that the obtained multifunctional 3D scaffold is an excellent candidate for diabetic wound healing and skin repair.

Effect of reduction through the Spin Coating growing Silver thin Films Nanostructure

Silver thin-film nanoparticles are prepared on the glass surface through a dependable method called spin coating. Silver nitrate (AgNO3) was utilized as precursors, proceeded by the thermal reduction in the H2 atmosphere, and some of the chemical reductions such as sodium borohydride (NaBH4) solution, and hydrazine hydrate solution (N2H4). The effects of several reductants have been discussed. The structure, morphology, and absorbance spectra of the deposited silver thin films were characterized and measured by using the following techniques X-ray diffraction (XRD), Scanning electron microscope (SEM), as well as UV-visible- NIR absorption spectroscopy respectively, to study more about how the reduction procedure affects the formation of silver nanoparticles. As a result, thermal reduction in the H2 atmosphere is more effective than the chemical reduction in aqueous sodium borohydride and hydrazine hydrate solution for growing consistently sized dispersed silver nanoparticles.

A boron-11 NMR study of the stability of the alkaline aqueous solution of sodium borohydride that is both an indirect fuel and a direct fuel for low-temperature fuel cells

Alkaline aqueous solution of sodium borohydride NaBH4 (denoted SB-fuel) is an indirect fuel when it is used to generate H2 by hydrolysis, with the as-generated H2 feeding a fuel cell, and it is a direct fuel when it is an anodic fuel of a direct fuel cell. However, SB-fuel suffers from a major drawback: NaBH4 spontaneously hydrolyzes. Our study falls within this context. We studied the instability, at the NMR scale and over 12 weeks, of a series of SB-fuels (initial NaBH4 concentration from 3.65 to 31.22 wt%, NaOH concentration from 1 to 16 M, and temperature between −15 and 60 °C) to find the conditions at which SB-fuel can be stored for weeks in relative safety. We found that SB-fuel with a NaOH concentration of ≥8 M is relatively stable under cold conditions (−15 and 4 °C). In these conditions, NaBH4 is not prevented from hydrolyzing, but the reaction is significantly mitigated. Otherwise, our study highlights the gaps in our understanding of the SB-fuel, emphasizes SB-fuel is a new concept of fuel (it should not be seen as any current fuel), and points out the challenges for attaining higher technology readiness levels.

Establishment of Integrated Analysis Method for Probing and Reconstructing Hydrogenation Mechanism of a Model Reaction

The hydrogenation of 4-nitrophenol (4-NP) has attracted much attention, since it is typically used as a model reaction for evaluating newly developed catalysts, but its mechanism is still debated. Herein, Co(OH)2-modified CuO catalyst (Co(OH)2/CuO) was used for the reduction of 4-NP to 4-aminophenol (4-AP) in an aqueous sodium borohydride (NaBH4) solution. The reaction mechanism was investigated by UV-Vis spectroscopy (UV-Vis), high-performance liquid chromatography (HPLC), HPLC-Q-orbitrap high-resolution mass spectrometry (LC-MS/MS), and 1HNMR spectroscopy (1HNMR) as an integrated technology at different concentrations of NaBH4. Samples were taken at specified time intervals and monitored using UV-Vis, HPLC, LC-MS/MS, and 1HNMR. With the help of comprehensive analysis, eight intermediates, including azo and azoxy compounds, were effectively captured, and the variation tendency of each intermediate was determined, revealing that the hydrogenation of 4-NP proceeds via a coexistence of the direct and condensation routes. The integrated analysis methods were powerful technical supports for the study of the catalysis mechanism.

Synthesis of Gold Nanoparticles Using Tannin-Rich Extract and Coating onto Cotton Textiles for Catalytic Degradation of Congo Red

Gold nanoparticles (AuNPs) were synthesized under ambient conditions from chloroauric acid in aqueous solution at pH 4. Tannin-rich extract from Xylocarpus granatum bark was used as both reducing and capping agent, rapidly converting Au (I) salt to AuNPs. Transmission electron microscopy showed the as-prepared AuNPs to be predominantly spherical, with an average diameter of 17 nm. The AuNPs were tested for catalytic reduction of Congo red (CR), a carcinogenic azo dye, in aqueous sodium borohydride solution. Cotton samples were coated with the AuNPs, taking on a reddish-purple color. The samples showed significantly reduced tearing strength after coating, though tensile strength was unaffected. UV-visible spectroscopy was used to determine the dye concentration in the water. CR degradation was observed only when AuNPs were present, and the efficiency of degradation was strongly linked to the AuNP loading. The AuNP-coated fabrics left only a 4.7% CR concentration in the solution after 24 h and therefore promise as a heterogeneous catalyst for degradation of CR in aqueous solution.

Electrosynthesis of Ni-Co/Hydroxyapatite as a Catalyst for Hydrogen Generation via the Hydrolysis of Aqueous Sodium Borohydride (NaBH4) Solutions

To generate hydrogen from its storage as NaBH4, a catalyst was synthesized via an electrochemical method. The catalyst, Ni-Co, had hydroxyapatite as a support catalyst. The electrochemical cell consisted of a DC power supply, a carbon anode and cathode, and a bipolar membrane to separate the cell into two chambers. The current density was adjusted to 61, 91, and 132 mA/cm2. The electrolysis time was 30, 60, and 90 min. The particles produced were analyzed by XRD and SEM/EDX and tested in the hydrolysis of NaBH4 for hydrogen generation. The Ni-Co/HA catalyst test concluded that the period of time used for electrolysis during catalyst formation was positively correlated with the rate of NaBH4 hydrolysis in the production of hydrogen. The highest rate of hydrogen production was obtained using the synthesized catalyst with a current density of 92 mA/cm2. The NaBH4 hydrolysis reaction followed a first-order reaction with the rate constant of (2.220–14.117)•10-3 l/(g•min). The Arrhenius equation for hydrolysis reactions within the temperature range of 300–323 K is k = 6.5•10-6exp(-6000/T).

A green nanocomposite based modified cellulose/TiO2/Cinnamon bark for the reduction of toxic organic compounds using spectrophotometric technique

The current study, reported the fabrication of bio-nanocomposite catalyst based on sulfated carboxymethyl cellulose (S-CMC) and TiO2 nanoparticles composited with cinnamon bark (CIN) (CIN/S-CMC/TiO2). The prepared CIN/S-CMC/TiO2 bio-nanocomposite was produced as supporting material for the preparation of highly active zero valent metal nanoparticles (MNPs) The CIN/S-CMC/TiO2 loaded with mono Co, Cu and bimetallic Cu-Co metal ions were then reacted with aqueous solution of sodium borohydride in order to reduce the metal ions into their respective zero-valent MNPs (M0). The CIN/S-CMC/TiO2 bio-nanocomposite loaded with mono and bimetallic M0 were analyzed by FTIR, XRD, EDX and FE-SEM, which confirms the successful fabrication of M0 on the surface of CIN/S-CMC/TiO2 bio-nanocomposite. The M0/CIN/S-CMC/TiO2 bio-nanocomposites were utilized as an effective catalyst for the successful reduction of 4-nitrophenol (4NP) and azo dyes such as Congo Red (CR), Methyl Orange (MO) And Acid Red (AR). Among all the fabricated catalysts, Co-Cu/CIN/S-CMC/TiO2 displayed better catalytic activity for the reduction of 4-NP and toxic azo dyes in the existence of sodium borohydride, with apparent constants of 0.99 min−1, 0.747 min−1, 0.621 min−1 and 0.342 min−1 respectively. Despite of having enhanced catalytic capability, the proposed bio-nanocomposite catalyst could be easily recoverable from the reaction solution after complete reduction process and can be used several times for the reduction of new samples.

Rhodium(0), Ruthenium(0) and Palladium(0) nanoparticles supported on carbon-coated iron: Magnetically isolable and reusable catalysts for hydrolytic dehydrogenation of ammonia borane

We report the synthesis of magnetically isolable ruthenium(0), rhodium(0), and palladium(0) nanoparticles, supported on carbon-coated magnetic iron particles, and their employment as catalysts in hydrolysis of ammonia borane. Carbon-coated iron (C–Fe) particles are obtained by co-processing of iron powders with methane in a radio frequency thermal plasma reactor. The impregnation of ruthenium(III), rhodium(III) and palladium(II) ions on the carbon-coated iron particles followed by aqueous solution of sodium borohydride leads to the formation of respective metal(0) nanoparticles supported on carbon-coated iron, M0/C–Fe NP (M = Ru, Rh, and Pd) at room temperature. M0/C–Fe NPs are characterized using the ICP-OES, XPS, TEM, and EDX techniques and tested as catalysts for hydrolysis of ammonia borane at 298 K. The results reveal that Rh0/C–Fe, Ru0/C–Fe, Pd0/C–Fe catalysts provide turnover frequency of 83, 93, and 29 min−1, respectively, in this industrially important reaction. More importantly, these magnetically separable metal(0) nanoparticles show very high reusability with no noticeable activity loss in subsequent runs of hydrolysis evolving 3.0 equivalent H2 per mole of ammonia borane.

Electrocatalysis of Pd–Er bimetallic catalysts for methanol oxidation in alkaline media

The Pd–Er/C catalysts with different Pd/Er ratios were synthesized through a simple simultaneous reduction reaction with sodium borohydride in aqueous solution. The structural and morphological features were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. The electrocatalytic performance of those catalysts for methanol oxidation in alkaline media was tested using cyclic voltammetry (CV) and linear sweep voltammetry (LSV). It is found that the Pd-4Er/C catalyst has a higher catalytic activity than the Pd/C catalyst. CO stripping experiments show its good resistance to CO poisoning, which can be explained by a bifunctional mechanism. According to the results from the X-ray photoelectron spectroscopy (XPS), the higher content of metallic Pd caused by the doping of metal Er also accounts for the improvement of catalytic performance. This work provides a highly efficient catalyst for methanol electrooxidation in alkaline media.

Effect of the Conditions the Reaction on the Formation of Iron Nanoparticles during the Reduction of Iron(III) Ions with Sodium Borohydride

Abstract—Iron nanoparticles are obtained by reducing iron(III) chloride with sodium borohydride in aqueous solutions at room temperature without using stabilizing agents. The obtained samples are characterized by X-ray diffraction analysis, low-temperature adsorption of argon, and transmission electron microscopy. The effect of the concentration of reagent solutions, the molar ratio of reagents, and exposure to ultrasound and inert atmosphere (Ar) on the size and composition of the resulting particles is found. Depending on the conditions of borohydride reduction of iron salts in an aqueous solution, both agglomerates of iron nanoparticles (5–50 nm) of 200 nm or larger and individual iron nanoparticles of 1 to 20 nm in size can be obtained. The presence and concentration of wustite and magnetite in the composition of the obtained particles mainly depend on the concentration of the reducing agent.

Retreatment of a Print Damaged by Excessive Sodium Borohydride Bleaching

Abstract An etching that was visibly damaged as a result of previous bleaching with a 5.6 % aqueous sodium borohydride solution underwent retreatment involving washing to stabilize the embrittled paper and to remove potentially present bleaching residues. During a final immersion in a dilute calcium hydrogen carbonate solution administered for deacidification, an unexpected and severe blistering occurred that is explained as a recurrence of previous bleaching-related blistering. The blisters were laid down. The treatment concluded with a consolidation of the bleach-damaged paper surface using a 0.5 % gelatine solution applied by misting.

Mechanistic Study of Catalytic Hydride Reduction of −NO2 to −NH2 Using Isotopic Solvent and Reducer: The Real Hydrogen Source

The catalytic reduction of 4-nitrophenol to 4-aminophenol by using aqueous sodium borohydride (NaBH4) solution is the most widely used model reaction to evaluate the catalytic activity of nanoparti...

Synthesis, characterization and antimicrobial activity of colloidal copper nanoparticles stabilized by cationic thiol polyurethane surfactants

Metal nanoparticles have attracted considerable interest particularly because of the size dependence of physical and chemical properties and its enormous technological potential. Among different metal nanoparticles, copper nanoparticles have attracted great attention because copper is one of the most key metals in new technology. Chemical methods are used to synthesize copper nanoparticles. Chemical reduction is the most frequently applied method for the preparation of stable, colloidal dispersions in organic solvents. In this paper, the new cationic thiol polyurethane surfactants with different alkyl chain length were synthesized (PQ10, PQ14 and PQ18). The chemical structure of the synthesized surfactants was confirmed using infra-red spectroscopy (IR) and proton nuclear magnetic resonance spectroscopy (1HNMR). Copper nanoparticles colloidal solution of 40–80 nm diameters was prepared using sodium borohydride in aqueous solution at room temperature as reducing agent. The synthesized surfactants decrease the aggreegation of copper nanoparticles. The nanostructure of the synthesized surfactant with copper nanoparticles with diameters ranging from 31.5 to 10.3 nm was prepared and characterized using ultra violet spectrophotometer (UV), infra-red spectroscopy (IR) and transmission electron microscope (TEM). The results declare formation and stabilization of copper nanoparticle using synthesized cationic surfactants. Antimicrobial activity of the synthesized cationic surfactants and their nanostructure with copper nanoparticles were evaluated against pathogenic bacteria and fungi.

Three-dimensional nanoporous polyacrylonitrile-based carbon scaffold for effective separation of oil from oil/water emulsion

The hydrophobic nature of the substances has served as important tools for governing the spatial behaviors of various fibrous substances depending on their affinities to oils or organic liquids. Herein, electrospun two-dimensional (2D) polyacrylonitrile (PAN) fiber mat was converted into three-dimensional (3D) mesh by hydrogen gas foaming technique using aqueous sodium borohydride (NaBH4) solution, which on heating at high temperature under a nitrogen atmosphere produced ultra-light, low density, hydrophobic 3D carbon scaffold with distinct affinities to oil phases. The fibrous materials were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FT-IR) spectra. Specific surface area and porosity of the fiber were analyzed by the Brunauer-Emmett-Teller (BET) technique. The carbon scaffold exhibit dominance as absorbents for selectively separating oils such as diesel, canola oil, xylene, and n-hexane with absorption capacity from 68.71 g g−1 to 131.33 g g−1. More interestingly, the absorbed oils were readily collected by simple mechanical squeezing and the recovered 3D carbon scaffold could be reused for the successive absorptions. This carbon scaffold could be a versatile platform to offer a kind of efficient and selective absorbent material for absorption of oils or organic liquids from the water.

Hydrogen Generation from Sodium Borohydride Solution Catalyzed By Cobalt-Boron-Manganese Coated on Ni Foam Substrate

In this study the cobalt-boron-manganese (CoBMn) films were deposited on the nickel foam (Nifoam) substrate and used as catalysts for hydrogen generation from an alkaline sodium borohydride solution. Thin CoBMn films were deposited on the Ni foam using morpholine borane as a reducing agent. The morphology and composition of the prepared catalysts were examined using Field Emission Scanning Electron Microscopy and Inductively Coupled Plasma Optical Emission Spectroscopy. Catalytic activity of the CoBMn/Ni foam catalyst was determined by measuring the amount of hydrogen generated directly from aqueous alkaline solutions of sodium borohydride (NaBH4) at different solution temperatures from 40 to 70 °C and compared with that of CoB/Ni foam. It was found that the rate of catalytic hydrolysis of NaBH4 in an alkaline solution catalyzed by the CoB/Ni foam and CoBMn/Ni foam increases exponentially with increase in reaction temperature. The activation energy was determined from the kinetic data. Significantly greater hydrogen generation rate is obtained at the CoBMn/Ni foam as compared with that at CoB/Ni foam. Acknowledgment This research was funded by a grant (No. M-ERA.NET-1/2016) from the Research Council of Lithuania.

Ceria supported manganese(0) nanoparticle catalysts for hydrogen generation from the hydrolysis of sodium borohydride

Herein we report for the first time the preparation and catalytic use of the ceria supported manganese(0) nanoparticles in hydrogen generation from the hydrolysis of sodium borohydride. They are in situ formed from the reduction of manganese(II) ions on the surface of ceria nanopowders during the catalytic hydrolysis of sodium borohydride in aqueous solution at room temperature. Manganese(0) nanoparticles are isolated from the reaction solution by centrifugation and characterized by a combination of analytical techniques. Nanoceria supported manganese(0) nanoparticles are highly active and long-lived catalysts providing a turnover frequency of 417 h−1 and 45,000 turnovers in hydrogen generation from the hydrolysis of sodium borohydride at 25.0 ± 0.1 °C. They also have high durability as they retain 55% of their initial catalytic activity after the fifth cycle of hydrolysis providing a release of 4 equivalent H2 gas per mol of sodium borohydride. The noticeable activity loss in successive runs of hydrolysis is attributed to the deactivation due to agglomeration. High activity and stability of ceria supported manganese(0) nanoparticles are ascribed to the unique nature of reducible cerium oxide. The formation of cerium(III) defects under catalytic conditions provides strong binding for the manganese(0) nanoparticles to oxide surface which makes the catalytic activity and stability favorable. Our report also includes the results of kinetic study of catalytic hydrolysis of sodium borohydride depending on the temperature, catalyst and substrate concentration.