Anion Exchange Research Articles

Heterophase Intermetallic Compounds for Electrocatalytic Hydrogen Production at Industrial-Scale Current Densities.

Heterophase nanomaterials have sparked significant research interest in catalysis due to their distinctive properties arising from synergistic effects of different components and the formed phase boundary. However, challenges persist in the controlled synthesis of heterophase intermetallic compounds (IMCs), primarily due to the lattice mismatch of distinct crystal phases and the difficulty in achieving precise control of the phase transitions. Herein, orthorhombic/cubic Ru2Ge3/RuGe IMCs with engineered boundary architecture are synthesized and anchored on the reduced graphene oxide. The Ru2Ge3/RuGe IMCs exhibit excellent hydrogen evolution reaction (HER) performance with a high current density of 1000 mA cm-2 at a low overpotential of 135 mV. The presence of phase boundaries enhances charge transfer and improves the kinetics of water dissociation while optimizing the processes of hydrogen adsorption/desorption, thus boosting the HER performance. Moreover, an anion exchange membrane electrolyzer is constructed using Ru2Ge3/RuGe as the cathode electrocatalyst, which achieves a current density of 1000 mA cm-2 at a low voltage of 1.73 V, and the activity remains virtually undiminished over 500 h.

Thermal Shock Synthesis for Loading Sub-2nm Ru nanoclusters on Titanium Nitride as a Remarkable Electrocatalyst towards Hydrogen Evolution Reaction.

Heterogeneous catalysts embracing metal entities on suitable supports are profound in catalyzing various chemical reactions, and substantial synthetic endeavors in metal-support interaction modulation have been made to enhance catalytic performance. Here, it is reported the loading of sub-2nm Ru nanocrystals (NCs) on titanium nitride support (HTS-Ru-NCs/TiN) via a special Ru-Ti interaction using high temperature shock (HTS) method. Direct dechlorination of the adsorbed RuCl3, ultrafast nucleation process and short coalescence duration at ultrahigh temperatures contribute to the immobilization of Ru NCs on TiN support via producing the Ru-Ti interfacial perimeter. HTS-Ru-NCs/TiN shows remarkable activity towards hydrogen evolution reaction (HER) in alkaline solution, yielding ultralow overpotentials of 16.3 and 86.6mV to achieve 10 and 100mAcm-2, respectively. The alkaline and anion exchange membrane water electrolyzers assembled using HTS-Ru-NCs/TiN yield 1.0Acm-2 at 1.65 and 1.67V, respectively, which validate its applicability in hydrogen production industry. Theoretical simulations reveal the favorable formation of Ru-O and Ti-H bond at the interfacial perimeters between Ru NCs and TiN, which accelerates the prerequisite water dissociation kinetics for the enhanced HER activity. This exemplified work motivates the design of specific interfacial perimeters via the HTS strategy to improve the performance of diverse catalysis. This article is protected by copyright. All rights reserved.

Efficient and durable seawater electrolysis with a V2O3-protected catalyst.

The ocean, a vast hydrogen reservoir, holds potential for sustainable energy and water development. Developing high-performance electrocatalysts for hydrogen production under harsh seawater conditions is challenging. Here, we propose incorporating a protective V2O3 layer to modulate the microcatalytic environment and create in situ dual-active sites consisting of low-loaded Pt and Ni3N. This catalyst demonstrates an ultralow overpotential of 80 mV at 500 mA cm-2, a mass activity 30.86 times higher than Pt-C and maintains at least 500 hours in seawater. Moreover, the assembled anion exchange membrane water electrolyzers (AEMWE) demonstrate superior activity and durability even under demanding industrial conditions. In situ localized pH analysis elucidates the microcatalytic environmental regulation mechanism of the V2O3 layer. Its role as a Lewis acid layer enables the sequestration of excess OH- ions, mitigate Cl- corrosion, and alkaline earth salt precipitation. Our catalyst protection strategy by using V2O3 presents a promising and cost-effective approach for large-scale sustainable green hydrogen production.

Isolation of short RNAs with homogenous 3’-ends using quaternary-amine anion exchange chromatography

Isolation of short RNAs with homogenous 3’-ends using quaternary-amine anion exchange chromatography

Balancing the Binding of Intermediates Enhances Alkaline Hydrogen Oxidation on D-Band Center Modulated Pd Sites.

Exploring efficient alkaline hydrogen oxidation reaction (HOR) electrocatalysts is of great concern for constructing anion exchange membrane fuel cells (AEMFCs). Herein, d-band center modulated PdCo alloys with ultralow Pd content anchored onto the defective carbon support (abbreviated as PdCo/NC hereafter) are proposed as highly efficient HOR catalyst. The as-prepared catalyst exhibits exceptional HOR performance compared to the Pt/C catalyst, achieving thermodynamically spontaneous and kinetically preferential reactions. Specifically, the resultant PdCo/NC demonstrates a marked enhancement in alkaline HOR performance, with the highest mass and specific activities of 1919.6 mA mgPd-1 and 1.9 mA cm-2, 51.1 and 4.2 times higher than those of benchmark of Pt/C, along with an excellent stability in a chronoamperometry test. In the analysis of in situ Raman spectra, it was discovered that tetrahedrally coordinated H-bonded water molecules were formed during the HOR process. This indicates that the promotion of interfacial water molecule formation and enhancement of HOR activities in PdCo/NC are facilitated by defect engineering and the turning of d-band center in PdCo alloy. The essential knowledge obtained in this study could open up a new direction for modifying the electronic structure of cost-effective HOR catalysts through electronic structure engineering.

A New 2-Aminospiropyrazolylammonium Cation with Possible Uses in the Topical Areas of Ionic Liquids

Based on the fact that 2-aminospiropyrazolinium compounds and structurally related azoniaspiro compounds belong, in a broad sense, to the class of ionic liquids, we have reviewed them and studied their practical applications. To search for possible uses of a new 2-aminospiropyrazolinium compounds, it is necessary to undertake a comparison with the related class of azoniaspiro compounds based on available information. The structures of the well-studied class of azoniaspiro compounds and the related but little-studied class of 2-aminospiropyrazolinium have rigid frameworks, limited conformational freedom, and a salt nature. These properties give them the ability to organize the nearby molecular space and enable the structure-forming ability of azoniaspiro compounds in the synthesis of zeolites, as well as the ability to act as phase-transfer catalysts and have selective biological effects. Additionally, these characteristics enable their ability to act as electrolytes and serve as materials for anion exchange membranes in fuel cells and water electrolyzers. Thus, the well-studied properties of azoniaspiro compounds as phase-transfer catalysts, structure-directing agents, electrolytes, and materials for membranes in power sources would encourage the study of the similar properties of 2-aminospiropyrazolinium compounds, which we have studied in relation to in vitro antitubercular, antidiabetic, and antimicrobial activities.

Completely Methylene-Free Side Chain Enables Significant Microphase Separation at Medium IECs for Fuel-Cell Anion Exchange Membranes.

The introduction of hydrophobic side chain structures in anion exchange membranes (AEMs) to facilitate ion transport has been widely studied; however, low or moderate hydrophobic hydrocarbon and semifluorinated side chains are insufficient to induce a high degree of microphase separation. Herein, we design and prepare poly(aryl piperidinium) AEMs with completely methylene-free perfluorinated side chains, which can maximize the thermodynamic incompatibility between main- and side chains, thus enhancing microphase separation at medium ion exchange capacities (IECs). According to the molecular dynamics study, the methylene-free perfluorinated side chain leads to better hydration of cations. The hydroxide conductivity of the methylene-free perfluorinated side chain-grafted PAP-pF-1 membrane reaches 124.9 mS cm-1 at 80 °C, and the PAP-sF-1 with semifluorinated side chains and PAP-CH-1 with hydrocarbon side chains show lower conductivity (116.8 and 104.0 mS cm-1). The H2/O2 fuel cell using the PAP-pF-1 membrane demonstrates a remarkable peak power density (1651 mW cm-2 at 80 °C) and durability (greater than 300 h). This work provides a novel insight into enhancing microphase separation in AEMs; it opens up new possibilities for developing high-performance AEMs.

Instantaneous Thermal Energy for Swift Synthesis of Single-Atom Catalysts for Unparalleled Performance in Metal-Air Batteries and Fuel Cells.

Based on experimental and computational evidence, phthalocyanine (Pc) compounds in the form of quaternary bound metal-nitrogen (N) atoms are the most effective catalysts for oxygen reduction reaction (ORR). However, the heat treatment process used in their synthesis may compromise the ideal structure, causing the agglomeration of transition metals. To overcome this issue, we developed a novel method for synthesizing iron (Fe) single-atom catalysts with ideal structures supported by thermally exfoliated graphene oxide (GO). This was achieved through a short heat-treatment of only 2.5min involving FePc and N,N-dimethylformamide in the presence of GO. According to the synthesis mechanism revealed by this study, carbon monoxide acts as a strong linker between the single Fe atoms and graphene. It facilitates the formation of a structure containing oxygen species between FeN4 and graphene, which provides high activity and stability for the ORR. These catalysts possess an enormous number of active sites and exhibit enhanced activity towards the alkaline ORR. They have demonstrated excellent performance when applied to real electrochemical devices, such as zinc-air batteries and anion exchange membrane fuel cells. We expect that the instantaneous heat treatment method developed in our study will aid in the development of high-performing single-atom catalysts. This article is protected by copyright. All rights reserved.

Performance Evaluation and Durability Analysis of NiFeCoOx Catalysts for Alkaline Water Electrolysis in Anion Exchange Membrane Electrolyzers

Performance Evaluation and Durability Analysis of NiFeCoOx Catalysts for Alkaline Water Electrolysis in Anion Exchange Membrane Electrolyzers

Enhancing the physicochemical properties of nickel cobaltite catalyst for oxygen evolution reaction in anion exchange membrane water electrolyzers

Enhancing the physicochemical properties of nickel cobaltite catalyst for oxygen evolution reaction in anion exchange membrane water electrolyzers

Sorption Characteristics and Chromatographic Separation of 90Y3+ from 90Sr2+ from Aqueous Media by Chelex-100 (Anion Ion Exchange) Packed Column

There is growing demand for separation of 90Y carrier free from 90Sr coexisting to produce high purity 90Y essential for radiopharmaceutical uses. Thus, in this context the sorption profiles of Y3+ and Sr2+ from aqueous solutions containing diethylenetriaminepenta acetic acid (DTPA), ethylenediaminetetra-acetic acid (EDTA), acetic acid, citric acid, or NaCl onto Chelex-100 (anion ion exchange) solid sorbent were critically studied for developing an efficient and low-cost methodology for selective separation of Y3+ from Sr2+ ions (1.0 × 10−5 M). Batch experiments displayed relative chemical extraction percentage (98 ± 5.4%) of Y3+ from aqueous acetic acid solution onto Chelex-100 (anion ion exchanger), whereas Sr2+ species showed no sorption. Hence, a selective separation of Y3+ from its parent 90Sr2+ has been established based upon percolation of the aqueous solution of Y3+ and Sr2+ ions containing acetic acid at pH 1-2 through Chelex-100 sorbent packed column at a 2 mL min−1 flow rate. Y3+ species were retained quantitatively while Sr2+ ions were not sorbed and passed through the sorbent packed column without extraction. The sorbed Y3+ species were then recovered from the sorbent packed column with HNO3 (1.0 M) at a 1.0 mL min−1 flow rate. A dual extraction mechanism comprising absorption associated to “weak-base anion exchanger” and “solvent extraction” of Y3+ as (YCl6)3− and an extra part for “surface adsorption” of Y3+ by the sorbent is proposed. The established method was validated by measuring the radiochemical (99.2 ± 2 1%), radionuclide purity and retardation factor (Rf = 10.0 ± 0.1 cm) of 90Y3+ recovered in the eluate. Ultimately, the sorbent packed column also presented high stability for reusing 2-3 cycles without drop in its efficiency (±5%) towards Y3+ uptake and relative chemical recovery. A proposed flow sheet describing the analytical procedures for the separation of 90Y3+ from 90Sr2+ using chelating Chelex 100 (anion exchange) packed column is also included.

Molecular Insights into the Effect of Cholesterol on the Binding of Bicarbonate Ions in Band 3 Protein.

Band 3, or anion exchanger 1 (AE1), is one of the indispensable transmembrane proteins involved in the effective respiratory process of the human body and is primarily responsible for the exchange of bicarbonate and chloride anions across the plasma membrane of erythrocyte. However, the molecular mechanism of ion transport of Band 3 is not completely understood, yet. In this work, we systematically investigate the key binding sites of bicarbonate ions in Band 3 and the impact of cholesterol (CHOL) in lipid bilayers on bicarbonate ion binding using all-atom molecular dynamics (MD) simulations. We examine the dynamics of interactions of bicarbonate ions with Band 3 in the microsecond time scale and calculate the binding free energy of the anion in Band 3. The results indicate that the residue R730 of Band 3 is the most probable binding site for bicarbonate ions. CHOL enhances the bicarbonate ion binding by influencing the conformational stability of Band 3 and compressing the volume of the Band 3 cavity. These findings provide some insights into the bicarbonate ion binding in Band 3 and are helpful for understanding the anion exchange of Band 3.

PVDF-HFP-Based Pioneering Anion Exchange Membranes for Advanced Sulfuric Acid Enrichment with Reduced Water Mobility

PVDF-HFP-Based Pioneering Anion Exchange Membranes for Advanced Sulfuric Acid Enrichment with Reduced Water Mobility

Aliquat 336 in Solvent Extraction Chemistry of Metallic ReO4− Anions

A study of the liquid–liquid extraction of ReO4− anions from hydrochloric acid solutions using the ionic liquid Aliquat 336 (QCl: trialkyl(C8–C10)methylammonium chloride) via the well-known method of slope analysis along with the determination of the process parameters is presented. This study employs CCl4, CHCl3 and C6H12 as diluents. This study was carried out at room temperature (22 ± 2) °C and an aqueous/organic volumetric ratio of unity. The ligand effect on the complexation properties of ReO4− is quantitatively assessed in different organic media. The organic extract in chloroform media is examined through 1H, 13C and 15N NMR analysis as well as the HRMS technique and UV-Vis spectroscopy in order to view the anion exchange and ligand coordination in the organic phase solution. Final conclusions are given highlighting the role of the molecular diluent in complexation processes and selectivity involving ionic liquid ligands and various metal s-, p-, d- and f-cations. ReO4− ions have shown one of the best solvent extraction behaviors compared to other ions. For instance, the Aliquat 336 derivative bearing Cl− functions shows strongly enhanced extraction as well as pronounced separation abilities towards ReO4−.

Deciphering the function of the fifth class of Gα proteins: regulation of ionic homeostasis as unifying hypothesis

Trimeric G proteins transduce signals from a superfamily of receptors and each G protein controls a wide range of cellular and systemic functions. Their highly conserved alpha subunits fall in five classes, four of which have been well investigated (Gs, Gi, G12, Gq). In contrast, the function of the fifth class, Gv is completely unknown, despite its broad occurrence and evolutionary ancient origin (older than metazoans). Here we show a dynamic presence of Gv mRNA in several organs during early development of zebrafish, including the hatching gland, the pronephros and several cartilage anlagen, employing in situ hybridisation. Next, we generated a Gv frameshift mutation in zebrafish and observed distinct phenotypes such as reduced oviposition, premature hatching and craniofacial abnormalities in bone and cartilage of larval zebrafish. These phenotypes could suggest a disturbance in ionic homeostasis as a common denominator. Indeed, we find reduced levels of calcium, magnesium and potassium in the larvae and changes in expression levels of the sodium potassium pump atp1a1a.5 and the sodium/calcium exchanger ncx1b in larvae and in the adult kidney, a major osmoregulatory organ. Additionally, expression of sodium chloride cotransporter slc12a3 and the anion exchanger slc26a4 is altered in complementary ways in adult kidney. It appears that Gv may modulate ionic homeostasis in zebrafish during development and in adults. Our results constitute the first insight into the function of the fifth class of G alpha proteins.

Relationship between dietary fiber content and prebiotic potential of polysaccharides from the seaweeds of the North west coast of India

The macroalgae are a sustainable bioresource that can be harnessed for their functional food and nutraceutical applications. This study characterized the biochemical composition and bioactive potential of natural biological macromolecules, such as macroalgal polysaccharides extracted using a green, aqueous extraction process. The in-vitro antioxidant and antiglycemic activity of these polysaccharides were evaluated using model, free radical and antiglycemic compounds. The prebiotic potential of macroalgal polysaccharides were analysed based on their ability to promote the growth of two potential probiotic bacteria Lactobacillus acidophilus and L. bulgaricus and suppress the growth of enteric bacteria, Escherichia coli. Among the polysaccharides studied, the brown algal polysaccharide MPS8 MPS9 and MPS10 exhibited good antioxidant, antiglycemic and prebiotic activity. Based on infrared spectroscopy, the functional groups sulfation and carboxylation were identified in potential polysaccharides. The monosaccharide composition in the bioactive polysaccharides was determined using High Performance Anion Exchange Chromatography Pulse Amperometric detector (HPAEC-PAD). These bioactive polysaccharides were fractionated using ion exchange chromatography to purify it and further characterized using gel permeation chromatography and NMR spectroscopy. The results these polysaccharides are mainly composed of fucose and glucose which is due to the fucoidan and laminarin, respectively. Such macromolecules with high dietary fiber content and bioactivity are in global demand as functional food, nutraceutical and pharmaceutical formulations.

Long-range order enabled stability in quantum dot light-emitting diodes.

Light-emitting diodes (LEDs) based on perovskite quantum dots (QDs) have produced external quantum efficiencies (EQEs) of more than 25% with narrowband emission1,2, but these LEDs have limited operating lifetimes. We posit that poor long-range ordering in perovskite QD films-variations in dot size, surface ligand density and dot-to-dot stacking-inhibits carrier injection, resulting in inferior operating stability because of the large bias required to produce emission in these LEDs. Here we report a chemical treatment to improve the long-range order of perovskite QD films: the diffraction intensity from the repeating QD units increases three-fold compared with that of controls. We achieve this using a synergistic dual-ligand approach: an iodide-rich agent (aniline hydroiodide) for anion exchange and a chemically reactive agent (bromotrimethylsilane) that produces a strong acid that in situ dissolves smaller QDs to regulate size and more effectively removes less conductive ligands to enable compact, uniform and defect-free films. These films exhibit high conductivity (4 × 10-4 S m-1), which is 2.5-fold higher than that of the control, and represents the highest conductivity recorded so far among perovskite QDs. The high conductivity ensures efficient charge transportation, enabling red perovskite QD-LEDs that generate a luminance of 1,000 cd m-2 at a record-low voltage of 2.8 V. The EQE at this luminance is more than 20%. Furthermore, the stability of the operating device is 100 times better than previous red perovskite LEDs at EQEs of more than 20%.

Automated synthesis of [89Zr]ZrCl4, [89Zr]ZrDFOSquaramide-bisPh(PSMA) and [89Zr]ZrDFOSquaramide-TATE

BackgroundAutomated [89Zr]Zr-radiolabeling processes have the potential to streamline the production of [89Zr]Zr-labelled PET imaging agents. Most radiolabeling protocols use [89Zr][Zr(ox)4]4− as the starting material and oxalate is removed after radiolabeling. In some instances, radiolabeling with [89Zr]ZrCl4 as starting material gives better radiochemical yields at lower reaction temperatures. In this work, a fully-automated process for production of [89Zr]ZrCl4 is reported and its use for the synthesis of [89Zr]ZrDFOSq-bisPhPSMA and [89Zr]ZrDFOSq-TATE.ResultsA simple automated process for the isolation of [89Zr]ZrCl4 by trapping [89Zr][Zr(ox)4]4− on a bicarbonate-activated strong anion exchange cartridge followed by elution with 0.1 M HCl in 1 M NaCl was developed. [89Zr]ZrCl4 was routinely recovered from [89Zr][Zr(ox)4]4− in > 95% yield in mildly acidic solution of 0.1 M HCl in 1 M NaCl using a fully-automated process. The [89Zr]ZrCl4 was neutralized with sodium acetate buffer (0.25 M) removing the requirement for cumbersome manual neutralization with strong base. The mixture of [89Zr]ZrCl4 was used for direct automated radiolabeling reactions to produce [89Zr]Zr-DFOSquaramide-bisPhPSMA and [89Zr]ZrDFOSquaramide-TATE in 80–90% over all RCY in > 95% RCP.ConclusionsThis method for the production of [89Zr]ZrCl4 does not require removal of HCl by evaporation making this process relatively fast and efficient. The fully automated procedures for the production of [89Zr]ZrCl4 and its use in radiolabeling are well suited to support the centralized and standardized manufacture of multiple dose preparations of zirconium-89 based radiopharmaceuticals.

Non-precious high entropy alloys and highly alkali-resistant composite membranes based high performance anion exchange membrane water electrolyzers

Cost-effective highly efficient and stable catalysts and alkali-resistant anion exchange membranes (AEMs) are critical for practical applications of anion exchange membrane water electrolyzers (AEMWEs). Here, bifunctional non-precious FeCoNiCuMo high entropy alloys (HEAs), electrochemically deposited on nickel mesh as an anode (FeCoNiCuMo/NM) and on carbon paper as a cathode (FeCoNiCuMo/CP), together with a NiFe layered double hydroxide (LDH) loaded AEM (AEM/LDH), were developed for high performance AEMWEs. The AEMWE thus fabricated delivered an ultrahigh current density of 1777 mA cm−2 at 2 V and exhibited remarkable stability with a less than 0.1% cell voltage increase after a 100-hour operation at 100 mA cm−2 at 50 °C, largely outperforming those of the precious metal based AEMWE, composed of IrO2/NM as the anode and Pt/C/CP as the cathode, 1231 mA cm−2@2 V and 4.57% increase in cell voltages. Composition of the alkali-resistant, hydrophilic, and water electrolysis active NiFe LDH into the AEM improved not only the electrolyte uptake and operational stability, but also the efficiency of the AEMWE, with a 10% boost in current density achieved at 2 V and a reduction in cell voltage increases from 2.94% to 0.0951%. The present development demonstrates the practicality of AEMWEs toward green hydrogen production.

Hot-Injection Synthesis of Cesium Lead Halide Perovskite Nanowires with Tunable Optical Properties

Metal halide perovskite semiconductors have emerged as promising materials for various optoelectronic applications due to their unique crystal structure and outstanding properties. Among different forms, perovskite nanowires (NWs) offer distinct advantages, including a high aspect ratio, superior crystallinity, excellent light absorption, and carrier transport properties, as well as unique anisotropic luminescence properties. Understanding the formation mechanism and structure–property relationship of perovskite NWs is crucial for exploring their potential in optoelectronic devices. In this study, we successfully synthesized all-inorganic halide perovskite NWs with high aspect ratios and an orthorhombic crystal phase using the hot-injection method with controlled reaction conditions and surface ligands. These NWs exhibit excellent optical and electrical properties. Moreover, precise control over the halogen composition through a simple anion exchange process enables the tuning of the bandgap, leading to fluorescence emission, covering a wide range of colors across the visible spectrum. Consequently, these perovskite NWs hold great potential for efficient energy conversion and catalytic applications in photoelectrocatalysis.