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Due to the presence of heavy metals in wastewater treatment and manufacturing water purification processes in industries, investigations into potential methods have been widely conducted. In this paper, we report the incorporation of cation-exchange for removing heavy metals from aqueous solutions. We further investigated the properties cation-exchange using potential step method on PPy/PVS film at titanium electrode. Satisfactory results have been obtained with the small scale of experimental. It was found that the PPy/PVS film is able to remove heavy metal ions such as copper, nickel, and cobalt at very low concentrations, less than or equal to 10 mg/L, reducing them to approximately 1 mg/L. The Leica Q500MC Image Processing and Analysis system displayed the uneven deposition of heavy metal ions on the surface of PPy/PVS. Furthermore, Electron Spectroscopy for Chemical Analysis (ESCA) demonstrated the deposition of heavy metals on the PPy/PVS film.

Efficient and durable electrocatalysts toward alkaline hydrogen evolution reaction (HER) are of great significance for the widespread application of anion‐exchange membrane water electrolyzer (AEMWE). Numerous single‐phase catalysts, such as Ru2P, have been explored as efficient HER catalysts; however, many have failed to overcome the inherent sluggish kinetics of the two separate steps involved in the alkaline HER: water dissociation and hydrogen production. In this study, density functional theory calculations are conducted to identify promising combinations of Ir2P and Ru2P materials that promote fast cascade water dissociation and H2 production via kinetically favorable hydrogen spillover from the Ru2P surface to the adjacent Ir2P. An unprecedented construction of Ir2P cluster‐decorated Ru2P hollow nanotubes (c‐RP/IP HNTs), which feature a cooperative heterostructural synergy are developed. This configuration shows greater performance than commercial Pt/C, achieving an overpotential of 23.2 mV at 10 mA cm−2 and maintaining long‐term stability for 55 h in half‐cell tests. Furthermore, the practical AEMWE test, incorporating c‐RP/IP HNTs, demonstrated a remarkable single‐cell performance of 12.23 A cm−2 at 2.0 V and operated stably under 1.0 A cm−2 for over 250 h. This surpasses that of the state‐of‐the‐art proton‐exchange membrane WE. [ABSTRACT FROM AUTHOR]

Nanostructured ionic compounds have driven major technological advancements in displays, photovoltaics, and catalysis. Current research focuses on refining the chemical composition of such compounds. In this study, a strategy for creating stoichiometrically well‐defined nanoscale multiple‐cation systems, where the atomically precise structure maximizes the synergistic cooperation between cations at the atomic scale is reported. The unprecedented construction of Heusler‐type PtRuP2 double‐walled nanotubes through sequential anion/cation exchange reactions is demonstrated. The PtRuP2 catalyst exhibits record‐high catalytic performance and durability for the hydrogen evolution reaction (HER) in alkaline electrolytes and anion‐exchange membrane water electrolyzers. The investigations highlight the crucial role of Pt/Ru dual centers, providing multiple active sites that accelerate the HER kinetics within a single phosphide material, in the sequential operation of H2O activation/dissociation at Ru and H2 production at adjacent Pt sites. These findings open new avenues for optimizing ionic compound‐based HER electrocatalysts, offering platinum‐metal alternatives in acidic and alkaline media. [ABSTRACT FROM AUTHOR]

Synthesis of a Mn4+‐activated fluoride red‐emitting phosphor combining high efficiency, excellent thermal stability, and outstanding moisture resistance still remains a challenge. Herein, this work synthesizes a red‐emitting phosphor Cs2NbF6: Mn4+ (CNF: Mn4+) based on the cation‐exchange method. Interestingly, as a result of the redox reaction between Mn3+ (Mn2+) and Nb5+ ions during the exchange reaction, the real Mn4+ concentration is remarkably increased, while Nb5+ ions are reduced to Nb4+. The obtained optimum CNF: Mn4+ phosphor shows high internal and external photoluminescence (PL) quantum yield (QY) of 92% and 58%, respectively. Moreover, the CNF: Mn4+ exhibits excellent thermal stability (I@150 = 105%) and moisture resistance. A white light‐emitting diode (LED) packaged by combining blue diode chips, Y3Al5O12:Ce3+ yellow phosphor, and CNF: Mn4+ red phosphor demonstrates a low correlated color temperature (CCT) of 3872 K, high color rendering index (CRI) of Ra = 88, and a luminous efficacy of 105 lm W−1. The high‐performance of the white LED suggests the great potential of the CNF: Mn4+ narrowband red phosphor in display and lighting fields. [ABSTRACT FROM AUTHOR]

Photocatalytic hydrogen evolution (PHE) is an attractive green way to produce clean energy. Zeolite-supported titanium dioxide (TiO 2) offers a cost-efficient pathway to prepare an efficient and recyclable photocatalyst for PHE. As known, zeolite has an excellent cation exchange capacity, and the exchangeable cations show considerable influence on its properties. However, the effect of exchangeable cations within zeolite-supported TiO 2 photocatalysts on their PHE activity remains unclear. Here, we prepared a series of zeolite LTA-supported TiO 2 photocatalysts (TXA, X = Na, K, Ca) with various cations (Na+, K+, Ca2+) inside the zeolite and investigated the effect of cations on their PHE activity. The results demonstrated that all TXA photocatalysts exhibit significantly enhanced PHE activity, and TCaA shows the highest hydrogen evolution rate, which is 3.84 times higher than that of P25. According to experimental results, TCaA possesses a higher solid-acid concentration and a larger surface area, which provides more proton sources and active sites for PHE, facilitates charge separation, and reduces photogenerated electron-hole pair recombination. We believe this work will offer a new exploration strategy for regulating the PHE performance of zeolite-supported TiO 2 -based photocatalysts and shed new light on the rational design of cost-efficient PHE catalysts. [Display omitted] • Cation-exchanged LTA zeolites-supported TiO 2 were prepared for PHE catalysts. • Zeolites-supported TiO 2 photocatalysts show significantly enhanced PHE efficiency. • CaA-supported TiO 2 exhibits an HER rate of 3.84 times higher than pristine P25. • The improvement mainly stemmed from high specific areas and solid-acid sites. • The higher solid-acid concentration provides more proton sources for PHE. [ABSTRACT FROM AUTHOR]

In this work, a hierarchical ZnS‐SnS‐Sb2S3@C (ZTAS@C) submicron box has been successfully prepared via a facile cation‐exchange strategy and is used as advanced anode for Li‐ion batteries. The composition and morphology of the as‐prepared samples are measured by XRD, SEM and TEM, respectively. In addition, the as‐synthesized hollow ZTAS@C architecture delivers a rate capability of 1001, 862, 765, 621, and 419 mAh g−1 at 0.2, 0.5, 1.0, 2.0, and 4.0 A g−1, respectively, and maintains reversible specific capacity of 581 mAh g−1 after 100 cycles at 1.0 A g−1 with the high CE value around almost 100%. Since 1 mol Sb2S3 could hold 4.8 times more Li+ ions than ZnS, the as‐synthesized ZTAS@C delivers 2∼3 times more specific capacity than the un‐treated ZnS‐SnS@C sample without cation‐exchange during electrochemical testing. Moreover, the cycled ZTAS@C could maintain a relatively complete microscopic morphology of the submicron box with a lower electrode expansion rate of ∼131%. Owing to synergistic effects between ZnS‐SnS‐Sb2S3, such as stable structure from ZnS, faster ionic conductivity from SnS and higher capacity from Sb2S3 (theoretically 947 mAh/g), ZTAS@C anode showed excellent electrochemical enhancements as using for LIBs anode. Therefore, the cation exchange strategy should be a facile way to improve the rate performance and cycle stability of multi‐metals sulfide composites. [ABSTRACT FROM AUTHOR]

The sensitivity, accuracy, and stability of a photoelectrochemical (PEC) immunosensor directly depends on the type of sensing substrate and the efficiency of the recognition model in immobilizing biological elements within multilayer assemblies. In this work, a split-type PEC immunosensor integrating Ag nanoparticles-modified ZIF-8 (ZIF-8@Ag NPs)-assisted cation-exchange and Fe 2 O 3 /ZnIn 2 S 4 nanoarrays (NAs) as well-ordered sensing substrate and photoactive material was developed for the detection of carbohydrate antigen 72–4 (CA72–4), a novel gastric cancer target. With effectively harvesting visible light, the stability signal output and the rapid carrier separation, the Z-Scheme Fe 2 O 3 /ZnIn 2 S 4 NAs heterojunction was successfully grown on an indium tin oxide (ITO) electrode as the signal converter and sensing substrate via two-step solvothermal method. The ZIF-8@Ag NPs were employed as the signal label to release silver ions (Ag+), relying on the acidolysis in the 96-well plate. The released Ag+ initiated a cation-exchange (CE) reaction with the Fe 2 O 3 /ZnIn 2 S 4 NAs, forming Fe 2 O 3 /ZnIn 2 S 4 /Ag 2 S ternary complexes with higher photocurrent density. This resulted in a positive correlation trend between CA72–4 concentration (0.01 U/mL to 100 U/mL), and improved the recognition sensitivity of the sensor to trace target, with the limit of detection is 0.0032 U/mL. This work represents an important advancement in overcoming the limitations of multilayer assembly in constructing immunosensors, providing a valuable reference for trace detection of low-abundance disease-related biomarkers. [Display omitted] [ABSTRACT FROM AUTHOR]

Direct hydrazine fuel cells (DHzFCs) are promising energy conversion devices due to their high energy density and environmental friendliness. However, inefficient hydrazine oxidation (HzOR) remains a key bottleneck in achieving practical fuel cell performance. To address this challenge, precise material design and synthesis are necessary to modulate the electronic structure and maximize the utilization of active sites. Herein, we present a Ru-Co 3 O 4 catalyst, which is synthesized based on a cation exchange strategy through which Ru single atoms are embedded on the surface of Co 3 O 4. Theoretical calculations confirm that Ru single atoms show a stronger hybridization with hydrazine molecules near the Fermi level and significantly lower the energy barrier required for N-containing intermediate formation, contributing to a record-low onset potential of −0.15 V vs. RHE and a working potential of −0.115 V vs. RHE at 10 mA cm−2. The assembled DHzFC using Ru-Co 3 O 4 as the anode catalyst achieves an impressive power output of 310.7 mW cm−2. [Display omitted] • Cation exchange strategies were deployed to obtain fully utilized active sites. • Ru-Co 3 O 4 displays excellent HzOR activity, with a working potential of −0.115 V vs. RHE at 10 mA cm−2. • The introduction of Ru single atom leads to stronger hybridization with hydrazine molecules near the Fermi level. • The DHzFC assembled with Ru-Co 3 O 4 possesses impressive performance with a discharge power of up to 310.7 mW cm−2. [ABSTRACT FROM AUTHOR]

Well dispersible and stable single atom catalysts (SACs) with hydrophilic features are highly desirable for selective hydrogenation reactions in hydrophilic solvents towards important chemicals and pharmaceutical intermediates. A general strategy is reported for the fabrication of hydrophilic SACs by cation‐exchange approach. The cation‐exchange between metal ions (M = Ni, Fe, Co, Cu) and Na+ ions introduced in the skeleton of metal oxide (TiO2 or ZrO2) nanoshells plays the key role in forming M1/TiO2 and M1/ZrO2 SACs, which efficiently prevents the aggregation of the exchanged metal ions. The as‐obtained SACs are highly dispersible and stable in hydrophilic solvents including alcohol and water, which greatly facilitates the catalysis reaction in alcohol. The Ni1/TiO2 SACs have been successfully utilized as catalysts for the selective C=C hydrogenation of cinnamaldehyde to produce phenylpropanal with 98% conversion, over 90% selectivity, good recyclability, and a turnover frequency (TOF) of 102 h−1, overwhelming most reported catalysts including noble metal catalysts. [ABSTRACT FROM AUTHOR]

• The NdVO 4 /BiVO 4 Z-scheme heterojunction is synthesized by two-step cation-exchange process. • The oxygen production of NdVO 4 /BiVO 4 reaches 1543.16 μmol h−1 g−1, which is 3 times that of BiVO 4. • The introduction of the neodymium element can enhance the response of catalyst to near-infrared light. • The direction of electron transfer between NdVO 4 and BiVO 4 is revealed. Bismuth vanadate (BiVO 4) has been recognized as a favorable photocatalyst for generating oxygen from water decomposition using solar energy. While, BiVO 4 's optical activity is limited due to its low charge mobility, high photo-generated electron hole recombination rate and low infrared light response. Herein, an oxygen vacancy-riched NdVO 4 /BiVO 4 heterojunction with infrared absorption feature is successfully prepared by a two-step cation-exchange method using Na 5 V 12 O 32 nanowire as a precursor. The in-situ growth of BiVO 4 on NdVO 4 forms a close contact interface, forming a heterojunction structure and generating an internal electric field, and the oxygen vacancies generated during cation-exchange can serve as electron traps, promoting the separation of photogenerated electron-hole pairs at the heterojunction. Furthermore, the enhanced infrared absorption properties of NdVO 4 , which forms the heterojunction, broaden the spectral response range. As a result, the synergistic effect of improved heterojunctions due to oxygen vacancies and enhanced infrared absorption, the photocatalyst exhibits enhanced photocatalytic oxygen evolution activity under visible and near-infrared light irradiation, with an oxygen evolution rate of 1543.16 μmol h−1 g−1 under visible light, which is 3 times higher than that of bare BiVO 4. Oxygen can be generated even under near-infrared light. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cation-exchangeable layered Mg-silicate was obtained using MgCl 2 , SiO 2 , and urea. • Urea hydrolysis increased the solution pH and grew layered Mg-silicate (stevensite). • The amount of MgO 6 octahedral vacancies increased with the reaction temperature. • The amount of the vacancies influenced the adsorbed amount of cationic dye. • The layered Mg-silicate hybridized with cosmetic pigment, fluorophlogopite. This study aimed to prepare a hybrid of cation-exchangeable stevensite-like magnesium-layered silicate and a synthetic mica (fluorophlogopite). The magnesium-layered silicate was synthesized via the reaction of magnesium chloride with colloidal silica in the presence of urea under hydrothermal conditions (100 °C or 140 °C for 2 d). The cation-exchange capacity of the stevensite-like silicate was influenced by the operating temperature; specifically, a higher capacity was achieved at a higher temperature (0.42 meq/g stevensite at 140 °C and 0.36 meq/g at 100 °C). The capacity was also affected by the solution pH, which was directly related to the growth rates of the octahedral and tetrahedral sheets. Upon addition of fluorophlogopite into the starting mixture, direct crystallization of the stevensite-like layered silicate occurred on the fluorophlogopite particles via hydrothermal treatment for possible applications as a cosmetic pigment. [ABSTRACT FROM AUTHOR]

The judicious implantation of active metal cations into the surface of semiconductor nanocrystal (NC) through cation-exchange is one of the facile and viable strategies to enhance the activity of catalysts for photocatalytic CO2 reduction, by shortening the transfer pathway of photogenerated carriers and increasing the active sites simultaneously. However, cation-exchange is hard to achieve for halide perovskite NCs owing to the stable octahedron of [PbX6]4- with strong interaction between halogen and lead. Herein, we report a facile method to overcome this obstacle by replacing partial Br− with acetate (Ac−) to generate CsPbBr3 NC (coded as CsPbBr3−xAcx). A small amount of Ac− instead of Br− does not change the crystal structure of halide perovskite. Owing to the weaker interaction between acetate and lead in comparison with bromide, the corresponding octahedron structure containing acetate in CsPbBr3−xAcx can be easily opened to realize efficient cation-exchange with Ni2+ ions. The resulting high loading amount of Ni2+ as active site endows CsPbBr3−xAcx with an improved performance for photocatalytic CO2 reduction under visible light irradiation, exhibiting a significantly increased CO yield of 44.09 μmol·g−1·h−1, which is over 8 and 3 times higher than those of traditional pristine CsPbBr3 and nickel doped CsPbBr3 NC, respectively. This work provides a critical solution for the efficient metal doping of low-cost halide perovskite NCs to enhance their photocatalytic activity, promoting their practical applications in the field of photocatalysis. [ABSTRACT FROM AUTHOR]

In the petroleum industry, core flooding intended to study the relative permeability of the carbon dioxide–brine–rock system is carried out using predetermined wettability states where carbon dioxide saturated brine is injected to displace carbonated brine. This prevents mutual solubility and acidity generation to influence wettability during gas flooding stage. However, no one has yet found out if these systems retain their ambient wettability states despite the availability of relevant petrophysical models that are useful for developing suitable modes for contact angle calculation. The motivation of this study stems from this knowledge gap in issues related to wettability preservation in multiphase flow in porous media. In this paper, we have used published data on carbon dioxide–brine–rock systems to show that core plugs do retain their predetermined wettabilities. The basis for this inference is the calculation of a wettability dependent parameter and contact angle, using a derived petrophysical model based on Purcell's original equation. In addition to acid gas systems, a similar approach has also been applied to an oil–water system, which generally retains its predetermined wettability. Trends in contact vs. water saturation for both systems are found to be similar, indicating wettability preservation during core flooding. Consequently, we have demonstrated for the first time, the feasibility of contact angle calculation using our derived equation. [ABSTRACT FROM AUTHOR]

In this research, hydrothermal technology was used to decompose a strongly acidic Na+ form cation‐exchange resin, DIAION SK1B, containing a crosslinking moiety and a styrene moiety at subcritical water conditions in an alkaline media to obtain decomposed products that can be quickly separated, efficiently collected and recycled. The decomposed materials subjected to a liquid‐solid separation to obtain an aqueous phase containing a salt of a material with an alkali. Two different acids (formic acid and acetic acid) were introduced to the aqueous phase to precipitate the materials and then added to a water‐insoluble solvent to yield materials, to dissolve the precipitated materials into the solvent to obtain a solution containing the materials to be gathered. However, the experiment was performed in a tubular reactor and heated by a salt‐bath. The effects of reaction time, temperature, additives concentration as alkali catalyst and pH of the aqueous solutions on the degradation rate of sulfonated resin were investigated. It was found out that 350°C, 120 min, and 0.05 M NaOH is the optimum condition to attain complete decomposition of this resin. The maximum yield of formic acid in aqueous phase obtained from batch reactor experiments was occurred at optimum conditions. Total organic carbon (TOC) of the aqueous phase reached (38%) to its maximum value at optimum condition. More than 60% of the cation exchange resin was decomposed at optimum condition. [ABSTRACT FROM AUTHOR]

There is strong need to reduce the manufacturing costs and increase the downstream purification efficiency of high-value therapeutic monoclonal antibodies (mAbs). This paper explores the performance of a weak cation-exchange membrane based on the coupling of IDA to poly(butylene terephthalate) (PBT) nonwoven fabrics. Uniform and conformal layers of poly(glycidyl methacrylate) (GMA) were first grafted to the surface of the nonwovens. Then IDA was coupled to the polyGMA layers under optimized conditions, resulting in membranes with very high permeability and binding capacity. This resulted in IgG dynamic binding capacities at very short residence times (0.1–2.0 min) that are much higher than those achieved by the best cation-exchange resins. Similar results were obtained in the purification of a single-chain (scFv) antibody fragment. As is customary with membrane systems, the dynamic binding capacities did not change significantly over a wide range of residence times. Finally, the excellent separation efficiency and potential reusability of the membrane were confirmed by five consecutive cycles of mAb capture from its cell culture harvest. The present work provides significant evidence that this weak cation-exchange nonwoven fabric platform might be a suitable alternative to packed resin chromatography for low-cost, higher productivity manufacturing of therapeutic mAbs and antibody fragments.

In this study, we investigated the tannic acid (TA)-, Ca2+-, and mica-enabled interfacial assembly of nC 60 fullerene (FWS) and Na-saturated kaolinite (Na-Kl) with in and ex situ atomic force microscopy (AFM). The epitaxial growth of herringbone motif, two dimensional (2D) chiral clusters and 3D mounds were detected. π-π electron donor-acceptor (EDA) interactions drove the transformation of the FWS, and the symmetry of the muscovite substrate directed the epitaxial ordering of self-assembled herringbone motifs. A ternary mixture of Na-Kl/FWS/TA in the presence of Ca2+ produced double-stranded (ds) helices and 2D platelets of chiral clusters with a nano-porous monolayer on K+-treated muscovite surfaces. The weak hydration of exchangeable K+ and stronger electric fields possibly contributed to the 1D and 2D propagation of aggregates. However, the local increment in carbon content due to the nucleation of functionalized FWS on mica diminished the K+-induced electric field effect and facilitated the 3D growth of helical mounds. The diffusion limited mass-transfer of particulates across the Ehrlich-Schwoebel barrier (ESB) and screw dislocation assisted motion of particulates specifically at higher steps aided mound growth. Thus, the structural incorporation of FWS can substantially impede its interfacial transport and produce hierarchical hybrid mineral-enriched graphitic aggregates. [ABSTRACT FROM AUTHOR]

Abstract Manganese vanadate (Mn 2 V 2 O 7) nanosheets on titanium (Ti) foil are synthesized by a cation-exchange method using sodium vanadate nanowires as the precursor. By varying the cation-exchange time in manganese acetate (Mn(CH 3 COO) 2) aqueous solution, the tunable morphologies and chemical components of the samples are tested, compared and presented in detail. The evolution process contains cation-exchange of Mn2+ and Na+, newly generated H+ to dissolve vanadate, and precipitation manganese vanadate nanosheets on the original sodium vanadate nanowire surface. Furthermore, the thermal and crystal properties of the as-prepared nanosheets are evaluated by calcinations at different temperatures. The Mn 2 V 2 O 7 nanosheets obtained at 250 °C, which are used as electrode of lithium-ion battery, have the first discharge capacity of 1048.0 mAh g−1 at 50 mA g−1. After 100 cycles, the residual capacity is more than 800 mAh g−1. Graphical abstract Manganese vanadate nanosheets on titanium foil are successfully assembled using a cation-exchange method for the first time. As an electrode material, it presents good cyclic performance and high charge-discharge capacity. Image 1 Highlights • Manganese vanadate nanosheets are successfully prepared using a cation-exchange method. • Manganese vanadate nanosheets on titanium foil present a high electrochemical performance for lithium ion battery. • The evolution in this work opens a new way to fabricate inorganic vanadates. [ABSTRACT FROM AUTHOR]

Abstract Ternary nickel-cobalt compounds with nano-arrayed structures can be used as promising electrodes to obtain high-performance electrochemical energy storage devices. Thus, ternary nickel-cobalt selenide, (Ni x Co 1-x) 0.85 Se, nanosheet arrays are successfully synthesized via a two-step method consisting of hydrothermal and cation-exchange process, then directly used as binder-free electrodes for supercapacitors. Characterization results indicate that the morphologies and chemical composition of (Ni x Co 1-x) 0.85 Se can be regulated by altering the reaction time. Electrochemical tests suggest that (Ni 0.5 Co 0.5) 0.85 Se nanosheet arrays possess the best electrochemical properties, i.e. : a maximum specific capacity of 430.87 mA h g−1 at 1 A g−1 and good cycling stability with 85.25% capacity retention after 3000 cycles. In addition, hybrid supercapacitors based on (Ni 0.5 Co 0.5) 0.85 Se nanosheet arrays and nitrogen-doped porous carbon can deliver a high energy density of 70.58 Wh kg−1 at power density of 320.02 W kg−1, as well as 91.88% capacitance retention after 8000 cycles, indicating that (Ni 0.5 Co 0.5) 0.85 Se nanosheet arrays has higher applicable value in energy-storage fields. Graphical abstract Image 1 Highlights • Ternary (Ni x Co 1-x) 0.85 Se nanosheet arrays were fabricated via a two-step method. • Morphologies and chemical composition of (Ni x Co 1-x) 0.85 Se can be regulated by altering the reaction time. • (Ni 0.5 Co 0.5) 0.85 Se nanosheet arrays possess the best electrochemical properties. • Hybrid supercapacitors based on the optimal sample show the higher applicable value in energy-storage. [ABSTRACT FROM AUTHOR]

Highlights • Cobalt vanadate nanowire array is synthesized by a cation-exchange routine. • Room temperature anisotropic ferromagnetic is found in the sample. • The enhanced ferromagnetic is derived from the uniformly distributed of Co2+. • Calcination is beneficial to enhance the magnetic properties of the sample. Abstract Room temperature diluted magnetic semiconductor nanomaterials play an important role in the preparation of novel micro-nano semiconductor devices. Herein, magnetic cobalt vanadate nanowire array is fabricated via a simple one-step cation-exchange method, which is confirmed to be a new kind of one-dimensional room temperature ferromagnetic semiconductors. Anisotropic magnetic with an easy direction of magnetization either perpendicular or parallel to the nanowire axis are found in the samples. Structural reorganization during calcination is beneficial to enhance the magnetic properties of the materials (Ms = 0.081 emu g−1 after calcination at 500 °C). Our investigation indicates that the room temperature anisotropic ferromagnetic of the samples is derived from the uniformly distributed cobalt element in the samples. The cation-exchange method in this work is easily applicable to synthesis similar room temperature ferromagnetic vanadate nanomaterials. [ABSTRACT FROM AUTHOR]

In the last two decades, the synthesis of inorganic nanostructures was boosted due to the impressive development of colloidal chemistry, which allowed obtaining a multiplicity of objects with finely regulated and uniform morphology, crystal structure and chemical composition. Moreover, different post-synthetic approaches further contributed to this development, one of the most used being cation-exchange, i.e . a method to partially or totally replace the cations of the starting ionic nanostructure. Meanwhile, transmission electron microscopy knew a new flourishing mainly due to the commercial availability of ultra-bright electron sources and spherical aberration correctors, whose combination permitted using very intense beams with concomitant point resolution better than 0.1 nm, and of ultrasensitive/ultrafast new electron cameras. In turn, these terrific improvements gave rise to an unprecedented progress of in situ electron microscopy, which consists of the live, direct observation over time of sample changes caused by external stimuli. Here we review how the in situ electron microscopy has been capable of promoting and imaging cation-exchange reactions at the solid state involving colloidal nanostructures, whose fast evolution during reactions in liquid would have made them otherwise not investigable.

Graphical abstract Highlights • Iron vanadate nanowires were firstly synthesized by a cation-exchange routine. • Well-dispersed porous iron vanadate nanowires firmly anchored on Ti foil. • The iron vanadate nanowires exhibit superior lithium storage capability. • The charge-discharge process prefers to pseudocapacitive-controlled behavior. Abstract The nanostructuring of materials can solve the problem of low conductivity of the vanadate electrode, thereby increasing the potential for lithium storage performance. The traditional battery is prepared by coating active materials on current collector, which produces large contact resistance between the current collector and the electrodes, impeding the overall electrochemical performances of the battery. In this work, we propose and verify a scheme for directly loading porous iron vanadate nanowire array electrode on titanium foil. The resultant electrode (the as-prepared iron vanadate annealed at 300 °C) exhibits an enhanced lithium storage performance, the discharge capacity after 100 cycles is 1041.10 mAh·g−1 at a current density of 300 mA·g−1. The iron vanadate nanowire electrode is fabricated by a simple and scalable cation-exchange method, which can be provided for the separate and integrated large-scale industrialization of vanadate electrode materials. [ABSTRACT FROM AUTHOR]

Radial-flow membrane chromatography is widely used for biopharmaceutical purification, particularly for separations carried out in the flow-through mode. In this article, we propose laterally fed membrane chromatography (LFMC) as an alternative to radial-flow membrane chromatography. LFMC has already been shown to be suitable for carrying out fast, high-resolution separations. In this study, we compare the performance of a radial-flow cation exchange membrane device with its equivalent LFMC device for flow-through separation of SP1, a recombinant protein that is currently under development by Sanofi Pasteur as a vaccine candidate. The flow-through of SP1 was monitored by UV absorbance while the breakthrough of the impurities such as host cell proteins was measured by analysing collected samples by Western blotting followed by densitometric scanning. The results obtained clearly demonstrated multiple-attribute superiority of the LFMC device in the above separation. [ABSTRACT FROM AUTHOR]

Liquid-liquid extraction of Eu3+ from aqueous solution with 4-oxaheptanediamides (OHAs) as extractant into room temperature ionic liquids (RTILs) of 1-alkyl-3-methylimidazolium hexafluorophosphate (Cnmim+PF6-, n = 4, 6 and 8) was investigated. The strong affinity of OHAs to Eu3+ was observed in the present Cnmim+PF6- system. The extraction was assumed to proceed by cation-exchange mechanism and formed a 4:1 complex of the OHA extractants and Eu3+ in C4mim+PF6- system. The preferable composition of extracted species was presumed to be Eu(OHA)4(H2O)4(PF6)3 by ESI-MS. [ABSTRACT FROM AUTHOR]

New cation exchanger monolithic stationary phases were prepared by immobilization of three different calixarene derivatives (i.e. tetracarboxylate calix[4]arene, CLX-COO , tetrasulfonate calix[4]arene, CLX-SO 3 , and tetraphosphonate calix[4]arene, CLX-PO 4 ) onto a monolithic cryogel support (i.e. poly(2-hydroksyethylmethacrilate- co -glycidyl methacrylate, P ) and investigated with respect to preparative protein chromatography. The obtained monoliths were characterized through various techniques such as FTIR spectroscopy, isoelectric point measurements, titrimetric analyses, and mercury intrusion porosimetry. Protein retention was investigated using some model proteins (i.e. lysozyme, cytochrome c , and ɑ-chymotrypsinogen A, human serum albumin, and myoglobin), and the role of modifier (i.e. NaCl) concentration and pH was thoroughly analyzed under isocratic and gradient elution conditions. Overloading experiments were also conducted to study dynamic adsorption capacity and the obtained values were found to be ranging between 3 and 8 mg/mL depending on the type of calixarene molecule. Hence, higher or comparable protein adsorption capacities were seen to be applicable on calixarene-immobilized cryogels when compared to any other functionalized cryogels in the literature. Combined with the favorable properties of these monoliths, with respect to mass transport of large molecules, these results qualify calixarene functionalized monolithic cryogels as promising stationary phases for protein preparative purification. [ABSTRACT FROM AUTHOR]

Abstract: Porous single‐crystalline nanostructures are of tremendous interest for their application in the catalytic, electronic and sensing fields due to their large active surfaces, favorable diffusion, and good electronic transport. Despite the recent advances of various other components, photoelectric chalcogenides remain almost undeveloped. The present study contributes a facile strategy to prepare porous single‐crystalline CdSe nanobelts through a cation‐exchange reaction, in which ZnSe⋅0.5 N2H4 hybrid nanobelts are employed as precursors. The detailed characterizations indicate the preservation of the belt‐like morphology of the precursors due to the spatial confinement effect, which arises from the coated surfactant layer during the cation‐exchange process. Simultaneously, CdSe nanobelts with porous and single‐crystalline structures are formed following a complete exchange between Zn2+ and Cd2+, the release of N2H4, and the atomic arrangement. The native photoelectric properties of the as‐prepared porous single‐crystalline CdSe nanobelts are systematically addressed based on the nanodevices fabricated with a single nanobelt and assembled nanobelt array. The results indicate that they present a rapid, stable, and repeatable photoelectric response. Moreover, as‐prepared nanobelts exhibit highly selective photoelectric sensing toward Cu2+ with a low detection limit down to 0.1 ppm. To illuminate this phenomenon, a possible sensing mechanism is also discussed. [ABSTRACT FROM AUTHOR]

Abstract: Porous single‐crystalline nanostructures are of tremendous interest for their application in the catalytic, electronic and sensing fields due to their large active surfaces, favorable diffusion, and good electronic transport. Despite the recent advances of various other components, photoelectric chalcogenides remain almost undeveloped. The present study contributes a facile strategy to prepare porous single‐crystalline CdSe nanobelts through a cation‐exchange reaction, in which ZnSe⋅0.5 N2H4 hybrid nanobelts are employed as precursors. The detailed characterizations indicate the preservation of the belt‐like morphology of the precursors due to the spatial confinement effect, which arises from the coated surfactant layer during the cation‐exchange process. Simultaneously, CdSe nanobelts with porous and single‐crystalline structures are formed following a complete exchange between Zn2+ and Cd2+, the release of N2H4, and the atomic arrangement. The native photoelectric properties of the as‐prepared porous single‐crystalline CdSe nanobelts are systematically addressed based on the nanodevices fabricated with a single nanobelt and assembled nanobelt array. The results indicate that they present a rapid, stable, and repeatable photoelectric response. Moreover, as‐prepared nanobelts exhibit highly selective photoelectric sensing toward Cu2+ with a low detection limit down to 0.1 ppm. To illuminate this phenomenon, a possible sensing mechanism is also discussed. [ABSTRACT FROM AUTHOR]

A mixed-mode polymer monolithic column functionalized by arsonic acid groups was prepared by single-step in situ copolymerization of monomers p -methacryloylaminophenylarsonic acid ( p -MAPHA) and pentaerythritol triacrylate (PETA). The prepared poly( p -MAPHA- co -PETA) monolithic column has a homogeneous monolithic structure with good permeability and mechanical stability. Zeta potential measurements reveal that the monolithic stationary phase holds a negative surface charge when the mobile phase resides in the pH range of 3.0–8.0. The retention mechanisms of prepared monolithic column are explored by the separation of selected polycyclic aromatic hydrocarbons (PAHs), nucleosides, and three basic compounds. The results indicate that the column functions in three different separation modes associated with reversed-phase chromatography based on hydrophobic interaction, hydrophilic interaction chromatography, and cation-exchange chromatography. The column efficiency of prepared monolithic column is estimated to be 70,000 and 76,000 theoretical plates/m for thiourea and naphthalene, respectively, at a linear flow velocity of 0.85 mm/s using acetonitrile/H 2 O (85/15, v/v) as the mobile phase. Furthermore, an analysis of the retention factors obtained for the PAHs indicates that the prepared monolithic column exhibits good reproducibility with relative standard deviations of 2.9%, 4.0%, and 4.7% based on run-to-run injections, column-to-column preparation, and batch-to-batch preparation, respectively. Finally, we investigate the separation performance of the proposed monolithic column for select phenols, sulfonamides, nucleobases and nucleosides. [ABSTRACT FROM AUTHOR]

DGA functionalized pillar[5]arene (P5DGA) in ionic liquid was demonstrated as highly efficient system for the extraction of plutonium from acidic aqueous solution in tetravalent and hexavalent oxidation state. The extraction followed ‘cation-exchange’ mechanism via [Pu.P5DGA]4+and [PuO2.P5DGA]2+, as extracted species for Pu4+and PuO22+, respectively. Evaluation of thermodynamic parameters (ΔG, ΔHand ΔS) showed the feasibility and spontaneity of the extraction process. The process was exothermic and primarily ‘enthalpy driven’, since entropy change was found negative. P5DGA-RTIL solvent system showed good radiolytic stability even at 1000 kGy of gamma dose. [ABSTRACT FROM PUBLISHER]

The existing classifications of extraction processes are overviewed. The main principles and/or criteria underlying each classification are considered. The three systems of classification of extraction processes suggested by A.M. Rozen are discussed in greater detail. [ABSTRACT FROM AUTHOR]

Enhancing anode performance in lithium-ion battery is one of the key directions to enable its efficiency as energy storage device. Conversion reaction provides an attractive strategy for such enhancement where reversible reaction between transition metal oxide and lithium ion enables very high capacity attainment. This work showed that homogeneous dispersion of nanoparticle Co 3 O 4 within carbon network can be obtained via a facile adsorption strategy using macroporous acrylic type cation-exchange resin and heat treatments. Co 3 O 4 was formed in situ carbon matrix utilizing cobalt acetate as cobalt ion precursor and catalyst for carbon graphitization. The lithium half-cell utilizing such anode demonstrated the highest capacity of 928 mAh g −1 at a current rate of 200 mA g −1 and excellent rate capability, i.e., it retained 630 mAh g −1 capacity at a current rate of 1600 mA g −1 and 470 mAh g −1 capacity at a current rate of 3200 mA g −1 . The composite demonstrated higher performance than its individual constituents which highlights the synergy effect upon combining Co 3 O 4 and carbon. In optimizing the performance, carbon to Co 3 O 4 ratio becomes an important variable. To obtain maximum capacity, we showed that CO 2 introduction during heat treatment can be utilized to reduce excess carbon content in such composite. [ABSTRACT FROM AUTHOR]

In this work, novel hierarchical Bi 2 MoO 6 nanotubes constructed from interconnected nanosheets have been fabricated and investigated as a high-performance electrochemical material. A facile template-engaged strategy has been utilized to controllably synthesize Bi 2 MoO 6 nanotubes by a reflux reaction. The nanotubes with a high surface area of 68.96 m 2 /g were constructed of highly ordered ultrathin nanosheets with a thickness of about 5 nm. Benefitting from the structural advantages including ultrathin nanosheets, large exposed surface, and unique three-dimensional tubular structure, the as-obtained hierarchical Bi 2 MoO 6 nanotubes exhibit excellent electrochemical performance. The specific capacitance of the hierarchical nanotubes can be up to 171.3 F g −1 at a current density of 0.585 A g −1 and excellent stability with 92.4% capacitance retention after 1000 cycles, which is much better than that of nanosheets (18.7 F g −1 at a current density of 0.585 A g −1 , 69.5% capacitance retention). [ABSTRACT FROM AUTHOR]

Hybrid materials, integrating the merits of individual components, are ideal structures for efficient oxygen evolution reaction (OER). However, the rational construction of hybrid structures with decent physical/electrochemical properties is yet challenging. Herein, a promising OER electrocatalyst composed of trimetallic metal-organic frameworks supported over S/N-doped carbon macroporous fibers (S/N-CMF@Fe x Co y Ni 1-x-y -MOF) via a cation-exchange strategy is delicately fabricated. Benefiting from the trimetallic composition with improved intrinsic activity, hollow S/N-CMF matrix facilitating exposure of active sites, as well as their robust integration, the resultant S/N-CMF@Fe x Co y Ni 1-x-y -MOF electrocatalyst delivers outstanding activity and stability for alkaline OER. Specifically, it needs an overpotential of 296 mV to reach the benchmark current density of 10 mA cm -2 with a small Tafel slope of 53.5 mV dec -1 . In combination with X-ray absorption fine structure spectroscopy and density functional theory calculations, the post-formed Fe/Co-doped γ-NiOOH during the OER operation is revealed to account for the high OER performance of S/N-CMF@Fe x Co y Ni 1-x-y -MOF., (© 2023 Wiley-VCH GmbH.)

All-inorganic cesium lead triiodide (CsPbI 3 ) perovskite has received increasing attention due to its intrinsic thermal stability and suitable band gap for photovoltaic applications. However, it is difficult to deposit high-quality pure-phase CsPbI 3 films using CsI and PbI 2 as precursors due to the rapid nucleation and crystal growth by the solution coating method. Here, a simple cation-exchange approach is employed to fabricate all-inorganic 3D CsPbI 3 perovskite, where 1D ethylammonium lead (EAPbI 3 ) perovskite is first solution-deposited and then transformed to 3D CsPbI 3 via ion exchange between EA + and Cs + during thermal annealing. The large space between the PbI 3 - skeletons in 1D EAPbI 3 favors the cation interdiffusion and exchange for the formation of pure-phase 3D CsPbI 3 with full compactness and high crystallinity and orientation. The resulting CsPbI 3 film exhibits a low trap density of state and high charge mobility, and the perovskite solar cell shows a power-conversion efficiency of 18.2% with enhanced stability. This strategy provides an alternative and promising fabrication route for the fabrication of high-quality all-inorganic perovskite devices.

We report the use of sulphonated waste polystyrene (SWPS) in the removal of heavy metal ions from water. Waste polystyrene (WPS) comprising of high impact polystyrene (HIPS) and expanded polystyrene (EPS) collected from dump sites in Harare were activated through sulphonation to produce a cation-exchange resin. The presence of the sulphonic group was studied with fourier transform infrared spectroscopy (FTIR). Flame atomic absorption spectrometry (FAAS) was used to determine the concentrations of residual metals (Zn 2+ , Pb 2+ ) after batch adsorption experiments. Sulphonated HIPS reduced Zn 2+ from 80 to 38.3 mg/L compared to 10–1.6 mg/L for sulphonated EPS. Similarly, sulphonated HIPS reduced Pb 2+ from 100 to 33 mg/L compared to 80–50.3 mg/L for sulphonated EPS. The adsorption data followed both the Langmuir and Freundlich isotherms and pseudo-second order kinetics. Maximum adsorption capacities as quantified by the Langmuir parameter q max for HIPS was 5.01 mg/g, EPS 0.38 mg/g for Zn 2+ and HIPS 6.80 mg/g, EPS 0.68 mg/g for Pb 2+ . The data were analysed using pseudo first order and pseudo second order Lagergren equation and the adsorption kinetics of the metals Pb 2+ and Zn 2+ was found to follow the pseudo second order kinetic model. Interpretation of the sorption data in terms of separation factor ( S F ) suggested that the removal of Pb 2+ and Zn 2+ from water mainly occurred through chemisorption. [ABSTRACT FROM AUTHOR]

The potential of enhanced-fluidity liquid chromatography, a subcritical chromatography technique, in mixed-mode hydrophilic interaction/strong cation-exchange separations is explored, using amino acids as analytes. The enhanced-fluidity liquid mobile phases were prepared by adding liquefied CO2 to methanol/water mixtures, which increases the diffusivity and decreases the viscosity of the mixture. The addition of CO2 to methanol/water mixtures resulted in increased retention of the more polar amino acids. The 'optimized' chromatographic performance (achieving baseline resolution of all amino acids in the shortest amount of time) of these methanol/water/CO2 mixtures was compared to traditional acetonitrile/water and methanol/water liquid chromatography mobile phases. Methanol/water/CO2 mixtures offered higher efficiencies and resolution of the ten amino acids relative to the methanol/water mobile phase, and decreased the required isocratic separation time by a factor of two relative to the acetonitrile/water mobile phase. Large differences in selectivity were also observed between the enhanced-fluidity and traditional liquid mobile phases. A retention mechanism study was completed, that revealed the enhanced-fluidity mobile phase separation was governed by a mixed-mode retention mechanism of hydrophilic interaction/strong cation-exchange. On the other hand, separations with acetonitrile/water and methanol/water mobile phases were strongly governed by only one retention mechanism, either hydrophilic interaction or strong cation exchange, respectively. [ABSTRACT FROM AUTHOR]

A novel Plutonium (Pu) (IV) selective ligand, bis-(2-ethylhexyl) carbamoyl methoxy phenoxy-bis-(2-ethylhexyl) acetamide (BenzoDODA) was studied for its Pu(IV) extraction behavior in presence of 1-alkyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl] imide {[C n mim][Tf 2 N]}ionic liquids. BenzoDODA was observed to behave differently in RTIL compared to n-dodecane toward Pu(IV) extraction. The presence of C 4 mimTf 2 N tends to bring about significant enhancement in the extraction of Pu in both the acidic media (HCl and HNO 3 ) as compared to that of using n-dodecane as diluent. The investigation of the extraction mechanism revealed that while using in RTIL (as diluent), the cation-exchange prevails up to 3 M acidity, in contrast to anion exchange mechanism ruling above 3 M acidic strength. However, in n-dodecane (as diluent) the metal extraction takes place via formation of anion-assisted neutral complex formation only at all acidities. Studies on the nature of species formed by Pu(IV) and BenzoDODA in both HNO 3 and HCl medium showed formation of a di-solvate species for RTIL in contrast to mono-solvate formed in n-dodecane. Selectivity of BenzoDODA-RTIL system appears to be lost at lower acidities due to significant extent of extraction of other matrix elements along with target metal ion. However at higher nitric acid concentration (7 M) BenzoDODA was found to be selectively extracting Pu(IV). [ABSTRACT FROM AUTHOR]

Ion-exchange (IEX) and Donnan dialysis (DD) are techniques which can selectively remove cations, limiting scaling in reverse osmosis (RO). If the RO concentrate could be recycled for regeneration of these pre-treatment techniques, RO recovery could be largely increased without the need for chemical addition or additional technologies. In this study, two different RO feed streams (treated industrial waste water and simple tap water) were tested in the envisioned IEX–RO and DD–RO hybrids including RO concentrate recycling. The efficiency of multivalent cation removal depends mainly on the ratio of monovalent to multivalent cations in the feed stream, influencing the ion-exchange efficiency in both IEX and DD. Since the mono-to-multivalent ratio was very high in the waste water, the RO recovery could potentially be increased to 92%. For the tap water, these high RO recoveries could only be reached by adding additional NaCl, because of the low initial monovalent to multivalent ratio in the feed. In both cases, the IEX–RO hybrid proved to be most cost-efficient, due to the high current cost of the membranes used in DD. The membrane cost would have to decrease from ±300 €/m² to 10–30 €/m² – comparable to current reverse osmosis membranes – to achieve a comparable cost. In conclusion, the recycling of RO concentrate to regenerate ion exchange pre-treatment techniques for RO is an interesting option to increase RO recovery without addition of chemicals, but only at high monovalent/multivalent cation-ratios in the feed stream. [ABSTRACT FROM AUTHOR]

Micro-capillary film (MCF) membranes are effective platforms for bioseparations and viable alternatives to established packed bed and membrane substrates at the analytical and preparative chromatography scales. Single hollow fibre (HF) MCF membranes with varied microstructures were produced in order to evaluate the effect of the bore fluid composition used during hollow fibre extrusion on their structure and performance as cation-exchange adsorbers. Hollow fibres were fabricated from ethylene-vinyl alcohol (EVOH) copolymer through solution extrusion followed by nonsolvent induced phase separation (NIPS) using bore fluids of differing composition (100 wt.% N -methyl-2-pyrrolidone (NMP), 100 wt.% glycerol, 100 wt.% water). All HFs displayed highly microporous and mesoporous microstructures, with distinct regions of pore size <1 μm, 5–15 μm and up to 50 μm in diameter, depending upon proximity to the bore fluid. Scanning electron microscopy (SEM) revealed skins of pore size <1 μm at the inner surface of HFs produced with water and glycerol, while NMP bore fluid resulted in a skinless inner HF surface. The HFs were modified for chromatography by functionalising the polymer surface hydroxyl groups with sulphonic acid (SP) groups to produce cation-exchange adsorbers. The maximum binding capacities of the HFs were determined by frontal analysis using lysozyme solutions (0.05–100 mg ml −1 ) for a flow rate of 1.0 ml min −1 . The NMP–HF–SP module displayed the largest maximum lysozyme binding capacity of all the fibres produced (40.3 mg lysozyme/ml adsorbent volume), a nearly 2-fold increase over the glycerol and 10-fold increase over the water variants at the same sample flow rate. The importance of NMP as a bore fluid to hollow fibre membrane performance as a result of inner surface porosity was established with a view to applying this parameter for the optimisation of multi-capillary MCF performance in future studies. [ABSTRACT FROM AUTHOR]

Bimetallic selenide heterojunction (CuSe/ZnSe@NC) is constructed from the partial replacement of Zn2+ by Cu2+ in ZnSe@NC nanobelts. Benefiting from reconfigured band structure, strong interfacial interactions and rich phase boundaries, the CuSe/ZnSe@NC heterojunction exhibits fast kinetics for sodium ion storage and impressive cycling capacity and stability. [Display omitted] • CuSe/ZnSe@NC heterojunction is prepared by cation-exchange reaction. • Abundant phase boundaries and strong interactions lead to charge redistribution. • Band structure of heterojunction is manipulated through the CuII(d9). • CuSe/ZnSe@NC presents lots of characteristics that surpass mono-metallic selenides. • Heterojunction delivers fast-charging capability and durable cycling life. Transition metal selenides have attracted extensive attention for sodium-ion batteries (SIBs) by virtue of high capacity and intrinsic safety. However, mono-metallic selenides suffer from the low conductivity and sluggish kinetics for Na+ ions transfer. Herein, bimetallic selenide (CuSe/ZnSe@NC) is constructed with modified band structure to boost the fast Na+ ions diffusion. Particularly, the implantation of heterojunction triggers the sublattice distortion and charge redistribution, which is beneficial to provide abundant active sites and regulate band structure. As expected, bimetallic CuSe/ZnSe@NC delivers the specific capacities of 411.5 mA h g−1 after 1000 cycles at 1 A g−1 and 361.8 mA h g−1 at 5 A g−1, indicating the superior cycle and rate performance than that of mono-metallic selenides. Meanwhile, in-situ XRD, TEM, and EIS further reveal the high reversibility and the conversion and alloying mechanisms of bimetallic CuSe/ZnSe@NC for SIBs. Moreover, first-principles calculations (DFT) further confirm that the fast Na+ ions diffusion is attributed to the optimized band structure and the charge rearrangement. Therefore, bimetallic heterojunctions not only combined the multifunctional properties, but also exhibited unique physicochemical properties that transcend mono-metallic selenides. [ABSTRACT FROM AUTHOR]