Tetra-n-butylammonium Hydroxide Research Articles

Self‐Assembling Delaminated V4C3Tx MXene into Highly Stable Pseudocapacitive Flexible Film Electrode for Supercapacitors

AbstractThe compactly stacked layers and the use of binders are detrimental to the rate performance and long cycle stability for V4C3Tx MXene. To solve this problem and add a new member to flexible electrodes, the multi‐layered V4C3Tx MXene is delaminated into nanoflakes (d‐V4C3Tx) with tetra‐n‐butylammonium hydroxide (TBAOH) and self‐assembled into the flexible film without binder. The d‐V4C3Tx film as a negative electrode delivers a high specific capacitance of 292.0 F g‐1 (622.4 F cm‐3) at 2 mV s‐1, remarkable rate performance (86.0% at 200 mV s‐1, 78.4% at 500 mV s‐1), and the splendid cycle stability (93.1% for 40 000 cycles, 82.9% for 60 000 cycles at 10 A g‐1). The excellent electrochemical performance for the d‐V4C3Tx film is attributed to the outstanding electrical conductivity (16 465.3 S m‐1), and the large interlayer spacing (2.1 nm), as well as the surface capacitive control mechanism. The asymmetric supercapacitor composed of d‐V4C3Tx film and activated carbon (AC) also shows high energy and power densities of 22.2 Wh L‐1 at 285.3 W L‐1. This work provides a novel flexible and more stable film (d‐V4C3Tx) electrode with long cycle life for supercapacitors, and further promotes the development for flexible supercapacitors.

Efficient photocatalytic degradation of commercial pharmaceutical contaminants of carbamazepine using BiOBr nanosheets under visible-light irradiation

Removing pharmaceutical contaminants is the growing concerns for the public people. Herein, commercial pharmaceutical drug of carbamazepine (CBZ) was degraded by photocatalysis. Highly efficient visible-light-driven BiOBr nanosheets were fabricated using water mediated hydrolysis route with the assistment of tetra (n-butyl) ammonium hydroxide (TBAOH). In particular, BiOBr nanosheets prepared with 0.1 mmol TBAOH (0.1 mmol TBAOH + KBr) performed the optimum photocatalytic degradation activity, enabling 88.7% removals of CBZ after 20 min irradiation under visible-light. Furthermore, 0.1 mmol TBAOH + KBr BiOBr nanosheets displayed fast degradation kinetics, with a degradation rate constant of 6.2 times than BiOBr prepared without TBAOH (0 mmol TBAOH + KBr). The enhanced photocatalytic activity was originated from the improvement of adsorption performance, photo absorption, and separation rate of photoinduced electron-hole pair. The major active species participated in CBZ degradation were proved to be h+, •O2-, and •OH using quenching experiments. The present results can throw light on the development of visible-light-driven photocatalyst with considerable catalytic activity for removing pharmaceutical contaminants.

Exfoliation of Nanosized α-Zirconium Phosphate in Methanol

The exfoliation of microcrystalline α-zirconium phosphate (α-ZrP) in an organic solvent is very difficult to achieve. Surprisingly, the addition of tetra(n-butyl)ammonium hydroxide (TBAOH) into a methanol dispersion of a nanosized α-ZrP brings about the complete exfoliation of nanosheets. To understand the mechanism, we examined the stepwise intercalation/exfoliation of the nanosized α-ZrP using TBAOH in four different solvents (water, methanol, ethanol, and butanol). Propionate groups on the edge of the nanosized α-ZrP prevent TBA cations from entering the galleries. Due to the formation of unstable solvent-intercalated α-ZrP with an increased interlayer distance in methanol and ethanol, TBA cations can overcome the steric hindrance and move into nanosheet layers to exchange with solvent molecules. However, the movability of the cations into the center of the galleries is preferred at a certain interlayer distance range, which leads to exfoliation of α-ZrP in methanol but intercalation only in ethanol. In water, in the beginning, neither intercalation nor exfoliation by TBA cations occurs. An additional amount of TBAOH causes the deformation of propionate groups and removes the barriers on the edges, followed by late intercalation and then exfoliation. On the other hand, butanol, as the solvent, is bulky and effectively limits the intercalation behavior of TBA cations. The weaker polarity of ethanol and butanol, compared with water and methanol, lowers the ion interactions in the solvent, which is another reason why they do not lead to exfoliation.

Reactions of [60]Fullerene with Acetone under Basic Condition: Nucleophilic Ring Opening of the [5,6]-Cyclopropane in C60 and Formation of the Substituted Methano[60]Fulleroids.

The reactions of C60 with acetone were carried out under basic condition in the presence of 1.0 M TBAOH (tetra-n-butylammonium hydroxide) methanol solution and ArCH2Br (Ar = Ph or o-BrPh), where methano[60]fulleroids with a novel 1,1,4,9,9,25-configuration were obtained and structurally characterized by single crystal diffraction. The product was formed via the ring-opening reaction of the [5,6]-cyclopropane by the nucleophilic addition of MeO-, which is different from the reactions of other ketones reported previously.

Ionic (Co)Organocatalyst with (Thio)Urea Anion and Tetra‑n‑butyl Ammonium Cation for the Polymerization of γ‐Butyrolactone

AbstractAn effective ionic organocatalyst system is developed for the challenging ring‐opening polymerization (ROP) of γ‐butyrolactone (GBL) at low temperature. The catalysts are prepared by dehydration reaction between tetra‐n‐butyl ammonium hydroxide (TBAOH) and (thio)ureas at ambient temperature, and utilized with or without extra benzyl alcohol (BnOH) initiator. The solid‐state structure of TUA‐3 comprising thiourea anion is characterized by X‐ray diffraction analysis. Typically, a mixture of cyclic and linear poly(GBL) with low molecular weights (5000–1600 g mol−1) and slightly narrow molecular distribution Ð (1.2–1.4) is obtained by single base with/without combination with (thio)ureas. Interestingly, solely linear high‐molecular‐weight poly(GBL) (10 400 g mol−1) can be achieved by a synergistic effect of TBAOH/N,N′‐isopropylthiourea in the presence of BnOH. The obtained poly(GBL) is characterized with NMR spectroscopy and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectroscopy (MALDI‐TOF MS). Mechanistic studies reveal different polymerization initiation steps in this reported catalyst system, which leads to poly(GBL) with divergent end groups.

One-step electrochemical deposition of thin film titanium suboxide in basic titanyl sulfate solution at room temperature

This study reports direct electrodeposition of TiOx thin films on ITO substrate from an acetonitrile solution containing titanyl sulfate and tetra n-butyl ammonium hydroxide. The electrochemical behavior of titanyl sulfate in a basic medium is investigated using cyclic voltammetry. In this medium, different phases and/or compositions containing Ti3O5 (βTi3O5, λTi3O5, and ɣTi3O5) and Ti4O7 are obtained depending on electrolysis potential values (− 1.2 V, − 1.5 V, − 1.7 V, and − 2.0 V). The electrochemical properties of the TiOx coatings obtained from various cathodic potentials are investigated using electrochemical impedance spectroscopy (EIS). Depending on the increase of electrolysis potential values applied, thicker films with lower resistance are formed. The EIS analysis results are compatible with the results of XRD and SEM, which confirms the change of phase content and/or composition in the films obtained at different electrolysis potential values. The estimated band gaps of brownish thin films are obtained between 1.32 and 1.41 eV using UV–vis spectra. Herein the electrochemical deposition of crystalline TiOx films on ITO electrode is carried out at room temperature by a cost-effective and one-step method in basic acetonitrile solution.

A luminescent cellulose ether with a regenerated crystal form obtained in tetra(n-butyl)ammonium hydroxide/dimethyl sulfoxide

Cellulose-based luminescent materials are usually formed via either covalent attachment or combination with luminogens. In this work, three luminescent cellulose ethers without conventional luminophores have been homogeneously synthesized in a mixed solvent of tetra(n-butyl)ammonium hydroxide (TBAH)/dimethyl sulfoxide (DMSO). The one obtained by etherifying microcrystalline cellulose (MCC) with 4-bromomethylbenzoic acid (BBA), i.e., MCC-BBA, exhibits a regenerated crystal form of IVII, whereas the other two are amorphous. The large difference of crystalline properties might be due to the formation of a new hydrogen bond network in MCC-BBA derived from the intermolecular interactions of COOH and their adjacent C2/C3OH groups. Such structural deviations might result in luminescence variations. Indeed, MCC-BBA can give brighter luminescence, which might be derived from crystallization-induced luminescence as well as photo-induced charge transfer effect. The presented work provides new insights into the rational synthesis of cellulose ethers, paving the way toward the design of non-conventional cellulose-based luminescent materials.

Elucidation of the Relationship between Intrinsic Viscosity and Molecular Weight of Cellulose Dissolved in Tetra-N-Butyl Ammonium Hydroxide/Dimethyl Sulfoxide.

The determination of molecular weight of natural cellulose remains a challenge nowadays, due to the difficulty in dissolving cellulose. In this work, tetra-n-butylammonium hydroxide (TBAH) and dimethyl sulfoxide (DMSO) aqueous solution (THDS) were used to dissolve cellulose in a few minutes under room temperature into true molecular solutions. That is to say, the cellulose was dissolved in the solution in molecular level, and the viscosity of the solution is linearly dependent on the concentration of cellulose. The relationship between the molecular weight of cellulose and the intrinsic viscosity tested in such dilute solutions has been established in the form of the Mark–Houwink equation, . The value of 1.21 indicates that the cellulose molecules dissolve in THDS quite well. The cellulose dispersion in the THDS was proved to be in molecular level by atomic force microscope (AFM) and dynamic light scattering (DLS). The reliability of the established Mark–Houwink equation was cross-checked by the gel permeation chromatography (GPC) and traditional copper (II) ethylenediamine (CED) method. No considerate degradation was observed by comparing the intrinsic viscosity and the degree of polymerization (DP) values of the original with and the regenerated cellulose samples. The natural cellulose can be molecularly dispersed in the multiple-component solvent (THDS), and kept stable for a certain period. A time efficient and reliable method has been supplied for determination of the degree of polymerization and the molecular weight of cellulose.

Selective separation of yttrium from rare earth elements by ion interaction chromatography. Analytical and larger scale applications

ABSTRACTNew ion interaction chromatographic (IIC) method employing Kromasil 100 C18 column and tetra-n-butylammonium hydroxide (TBAOH) as an ion interaction reagent (IIR) is able to separate yttrium from Rare Earth Elements (REE) as anionic complexes with nitrilotriacetic acid (NTA). New method for the chromatographic determination of Y in REE mixture was devised and validated by the analysis of the certified reference material (CRM). Potential possibilities of the new chromatographic system for larger scale applications including macro-micro events were demonstrated.

Ion interaction chromatography of anions in alkaline solutions: effect of temperature and the kind of stationary phase

ABSTRACTEffect of temperature (5°–65°C) on the separation of 11 inorganic anions by ion interaction chromatography (IIC) was studied employing RP C18 and C PhenylHexyl columns and aqueous mobile phase: 2.8 mM NaHCO3 + 0.7 mM TBAOH (tetra-n-butylammonium hydroxide). The apparent enthalpy changes, ΔH for hydrophobic ions like I−, SCN−, and ClO4 − largely exceeded 3 kcal/mole suggesting that added to ion exchange they are retained by hydrophobic adsorption. Unlike conventional strongly basic anion exchangers, our system can be used at elevated temperatures with alkaline eluents without irreversible damaging the column.

Functional Engineering of Perovskite Nanosheets: Impact of Lead Substitution on Exfoliation in the Solid Solution RbCa2–xPbxNb3O10

Tuning the chemical composition and structure for targeted functionality in two‐dimensional (2D) nanosheets has become a major objective in the rapidly growing area of 2D materials. In the context of photocatalysis, both miniaturization and extending the light absorption of UV active photocatalysts are major assets. Here, we investigate the solid solution between two photocatalytic systems known from literature to evolve H2 from water/methanol under UV – RbCa2Nb3O10 (Eg = 3.7 eV) – and visible light irradiation – RbPb2Nb3O10 (Eg = 3.0 eV) – by synthesizing hypothetical RbCa2–xPbxNb3O10. While the calcium niobate can easily be exfoliated into individual nanosheets via cation–proton exchange and subsequent treatment with tetra‐n‐butylammonium hydroxide (TBAOH), the lead niobate barely yields nanosheets. Spectroscopic and microscopic analysis suggest that this is caused by volatilization of Pb during synthesis, leading to a local 3D linkage of RbPb2Nb3O10 perovskite units with Pb deficient units. On the one hand, this linkage progressively prevents exfoliation along with an increasing Pb content. On the other hand, introducing Pb into the perovskite blocks successively leads to bandgap narrowing, thus gradually enhancing the light harvesting capability of the solid solution. Finding a compromise between this narrowing of the bandgap and the possibility of exfoliation, visible light sensitized nanosheets can be engineered in good yield for an initial molar ratio of Ca:Pb ≥ 1:1.

Solution-processed cellulose/melanin films and fibers

Melanins constitute a class of biomacromolecules that are abundant in nature. Although they exhibit a unique range of physical and chemical properties, their intractable nature has precluded their dissolution in common solvents and facile processing into functional materials. The authors found that commercially available 40 wt% tetra-n-butylammonium hydroxide (TBAH) solution could yield stable solutions of synthetic and natural melanins at ambient conditions and the dissolution rate could be accelerated by microwave radiation. Transmission electron microscopy images clearly show the disruption of the aggregated structure of melanins in TBAH. Scanning electron microscopy images of melanin/TBAH solutions precipitated in acetone revealed that melanins are dissolved and regenerated and not merely dispersed. To the best of the authors’ knowledge, this is the first report demonstrating a facile approach to solution processing of melanins with other biopolymers, which allows leverage of many unique properties of melanins. As an illustrative example, the authors demonstrate here the successful fabrication of cellulose/melanin composite films and fibers and their significant dye absorption capacity (62% reduction) with methylene blue.

Nanotubes Formed by Exfoliation of HTaWO6

A new tubular-structured nanomaterial was formed by exfoliating HTaWO6 with tetra-n-butylammonium hydroxide (TBAOH) at ambient temperature. The final product was characterized by AFM, SEM, and TEM....

Band Gap Extraction from Individual Two-Dimensional Perovskite Nanosheets Using Valence Electron Energy Loss Spectroscopy

Rapid progress in the synthesis of nanostructures with tailor-made morphologies necessitates adequate analytical tools to unravel their physical properties. In our study, we investigate, on the nanometer scale, the band gap of individual [TBAxH1–x]+[Ca2Nb3O10]− nanosheets obtained through intercalation–exfoliation of the layered bulk phase KCa2Nb3O10 with tetra-n-butylammonium hydroxide (TBAOH) using valence electron energy loss spectroscopy (VEELS) in the scanning transmission electron microscope (STEM). The nanosheets consist of an anionically charged perovskite layer with cationic organic ligands surrounding it. Because of the hybrid nature, a careful acquisition and analysis protocol is required since the nanosheets disintegrate easily under electron beam irradiation. The VEELS data reveal a fundamental band gap of an individual freely suspended perovskite nanosheet to be 2.9 ± 0.2 eV and optically allowed transitions above 3.8 ± 0.2 eV (optical band gap). The spatial resolution of the measurements is...

New reversed phase-high performance liquid chromatographic method for selective separation of yttrium from all rare earth elements employing nitrilotriacetate complexes in anion exchange mode

Separation of Y from other rare earth elements (REE) is difficult because of similarity of its ionic radius to ionic radii of Tb, Dy and Ho. In the new RP-HPLC system with C18 column, tetra-n-butyl ammonium hydroxide (TBAOH) as an ion interaction reagent (IIR), nitrilotriacetic acid (NTA) as a complexing agent at pH=2.8–3.5, and post column derivatization with Arsenazo III, yttrium is eluted in the region of light REE, between Nd and Sm and is base line separated from Nd and Sm and even from promethium. Simple model employing literature data on complex formation of REE with NTA and based on anion exchange mechanism was developed to foresee the order of elution of individual REE. The model correctly predicted that lanthanides up to Tb will be eluted in the order of increasing Atomic Number (At.No.) but all heavier REE will show smaller retention factors than Tb. Concurrent UV/VIS detection at 658nm and the use of radioactive tracers together with γ-ray spectrometric measurements made possible to establish an unique elution order of elution of REE: La, Ce, Pr, Nd, Pm, Y, Sm, Er, Ho, Tm, Yb, Eu, Lu, Dy+Gd, Tb, Sc. The real place of Y however, in this elution series differs from that predicted by the model (Y between Sm and Eu). The method described in this work enables selective separation of Y from La, Ce, Pr, Nd, Pm, Sm and all heavier REE treated as a group.

Deprotonation Reactions and Electrochemistry of Substituted Open-Chain Pentapyrroles and Sapphyrins in Basic Nonaqueous Media

Electrochemical and spectroelectrochemical properties of three open-chain pentapyrroles and the corresponding sapphyrins were examined in pyridine containing 0.1 M tetra-n-butylammonium perchlorate and dichloromethane (CH2Cl2) or benzonitrile (PhCN) containing tetra-n-butylammonium hydroxide (TBAOH). The investigated compounds are represented as (Ar)4PPyH3 and (Ar)4SH3, where Ar is a F(-) or Cl(-) substituted phenyl group, PPy is a trianion of the open-chain pentapyrrole, and S is a trianion of the sapphyrin. The pentapyrroles, (Ar)4PPyH3, undergo two reversible one-electron reductions in pyridine, while the structurally related sapphyrins exhibit four reductions in this solvent, the first two of which are irreversible due to coupled chemical reactions following the electron transfers. Both series of neutral compounds could be deprotonated in CH2Cl2 or PhCN by addition of TBAOH to solution, and the progress of these reactions was monitored as a function of the base concentration by cyclic voltammetry and UV-vis spectroscopy. The neutral pentapyrroles were spectroscopically shown to undergo a loss of two protons in a single step to generate the [(Ar)4PPyH](2-) dianion while the sapphyrins could only be monodeprotonated, leading to formation of the [(Ar)4SH2](-) monoanion under the same solution conditions. The deprotonation constants were measured for each series of compounds in benzonitrile, and oxidation-reduction mechanisms are examined as a function of the solution 'basicity'.

Tetranuclear Lanthanide (III) Complexes Containing Dimeric Subunits: Single-Molecule Magnet Behavior for the Dy4 Analogue

The reaction of the lanthanide(III) salts [Dy(III), Tb(III), and Gd (III)] with a hetero donor chelating ligand N'-(2-hydroxy-3-methoxybenzylidene)-6-(hydroxymethyl) picolinohydrazide (LH3) and pivalic acid (PivH) in the presence of tetra-n-butylammonium hydroxide (TBAH) afforded the tetranuclear Ln(III) coordination compounds, [Ln4(LH)2(LH2)2(μ2-η(1)η(1)Piv)2(η(1)Piv)4]·2CHCl3 [Ln = Dy(1), Tb(2), and Gd(3)]. The molecular structure of these complexes reveals that the tetranuclear derivatives are composed of two dinuclear subunits which are interconnected through the coordination action of the picolinoyl hydrazine ligand. Within each subunit two different types of Ln(III) ions are present. One of these is eight-coordinate in a distorted triangular dodecahedral geometry while the other is nine-coordinate in a distorted spherical capped square antiprism geometry. Alternating current (ac) susceptibility measurements of complex 1 reveal a frequency- and temperature-dependent two step out-of-phase signals under 1kOe DC field which is characteristic of a single-molecule magnet (SMM) behavior. Analysis of the magnetic data afforded the anisotropic barriers and relaxation times: Δ/kB = 62.6 K, τ0 = 8.7 × 10(-7) s; Δ/kB = 26.3 K, τ0 = 1.26 × 10(-6) s for the slow and fast relaxations respectively.

Wheat straw cellulose dissolution and isolation by tetra-n-butylammonium hydroxide

In this article, a novel and high efficient solvent, tetra-n-Butylammonium Hydroxide (TBAH), was used for dissolution and isolation of straw cellulose from wheat straw. The composition analysis with gas chromatography (GC) and the spectroscopic characterization analysis conducted by X-Ray diffraction (XRD)/Fourier transform infrared spectroscopy (FTIR) indicated that straw cellulose can be directly dissolved and isolated by TBAH without derivatization. The investigation on the properties of straw cellulose isolation was based on the results of single factor experiments and orthogonal experiments, with optimum conditions for straw cellulose isolation being obtained as follow: reaction temperature 60°C, reaction time 40min, concentration of TBAH 50% and ratio of TBAH to straw 10:1 (m/m). In addition, as a solvent for cellulose, TBAH could be recycled several times with high activity being retained.

Production of high purity solution of tetraalkylammonium hydroxide using ion-exchange process

The possibility of obtaining high-purity solutions of tetramethylammonium hydroxide and tetra-nbutylammonium hydroxide was examined by passing of appropriate tetraalkylammonium halide solution through a column of an anion exchanger in the base form. Optimizing a ratio of an amount of used resin to degree of conversion determined by the residual concentration of halogen ion was demonstrated.

Electroreduction and Acid–Base Properties of Dipyrrolylquinoxalines

The electroreduction and acid-base properties of dipyrrolylquinoxalines of the form H(2)DPQ, H(2)DPQ(NO(2)), and H(2)DPQ(NO(2))(2) were investigated in benzonitrile (PhCN) containing 0.1 M tetra-n-butylammonium perchlorate (TBAP). This study focuses on elucidating the complete electrochemistry, spectroelectrochemistry, and acid-base properties of H(2)DPQ(NO(2))(n) (n = 0, 1, or 2) in PhCN before and after the addition of trifluoroacetic acid (TFA), tetra-n-butylammonium hydroxide (TBAOH), tetra-n-butylammonium fluoride (TBAF), or tetra-n-butylammonium acetate (TBAOAc) to solution. Electrochemical and spectroelectrochemical data provide support for the formation of a monodeprotonated anion after disproportionation of a dipyrrolylquinoxaline radical anion produced initially. The generated monoanion is then further reduced in two reversible one-electron-transfer steps at more negative potentials in the case of H(2)DPQ(NO(2)) and H(2)DPQ(NO(2))(2). Electrochemically monitored titrations of H(2)DPQ(NO(2))(n) with OH(-), F(-), or OAc(-) (in the form of TBA(+)X(-) salts) give rise to the same monodeprotonated H(2)DPQ(NO(2))(n) produced during electroreduction in PhCN. This latter anion can then be reduced in two additional one-electron-transfer steps in the case of H(2)DPQ(NO(2)) and H(2)DPQ(NO(2))(2). Spectroscopically monitored titrations of H(2)DPQ(NO(2))(n) with X(-) show a 1:2 stoichiometry and provide evidence for the production of both [H(2)DPQ(NO(2))(n)](-) and XHX(-). The spectroscopically measured equilibrium constants range from log β(2) = 5.3 for the reaction of H(2)DPQ with TBAOAc to log β(2) = 8.8 for the reaction of H(2)DPQ(NO(2))(2) with TBAOH. These results are consistent with a combined deprotonation and anion binding process. Equilibrium constants for the addition of one H(+) to each quinoxaline nitrogen of H(2)DPQ, H(2)DPQ(NO(2)), and H(2)DPQ(NO(2))(2) in PhCN containing 0.1 M TBAP were also determined via electrochemical and spectroscopic means; this gave rise to log β(2) values ranging from 0.7 to 4.6, depending upon the number of nitro substituents present on the H(2)DPQ core. The redox behavior of the H(2)DPQ(NO(2))(n) compounds of the present study were further analyzed through comparisons with simple quinoxalines that lack the two linked pyrrole groups, i.e., Q(NO(2))(n) where n = 0, 1, or 2. It is concluded that the pyrrolic substituents play a critical role in regulating the electrochemical and spectroscopic features of DPQs.