Cation Exchange Synthesis Research Articles

Removing Cadmium Impurities from Cation‐Exchange‐Derived CuInSe2/CuInS2 Nanorods for Enhanced Infrared Emission and Photodetection

AbstractMetal chalcogenide nanocrystals with variable composition and shape can conveniently be produced using cation exchange synthesis; however, the presence of cation‐containing ligands inherited from the starting material often results in contamination of the final product. To address this issue, a two‐step ligand replacement strategy is developed to fabricate CuInSe2/CuInS2 nanorods from CdSe/CdS nanorods via removal of Cd‐phosphonates from an intermediate Cu2‐xSe/Cu2‐xS phase used in the cation exchange conversion. This synthetic approach furnishes CuInSe2/CuInS2 nanorods with cadmium content below 1 at.%, and high photoluminescence quantum yields reaching 40% in the near‐infrared spectral range. Transient absorption studies reveal that the band alignment in the CuInSe2/CuInS2 heterostructure features a quasi‐type II character, with an electron localized in the core and a hole wavefunction spread over the entire nanorod. The efficient passivation of the core and the reduced Cd content leads to excitonic emission with full width at half maximum down to 110 meV, superimposed with a broad emission band from copper‐induced defects. Field‐effect transistors based on cadmium‐free CuInSe2/CuInS2 nanorods show two orders of magnitude lower noise current density compared with the cadmium‐rich devices. The responsivity and specific detectivity of these devices reach 230 mA W−1 and 108 Jones, respectively, under near‐infrared excitation at room temperature.

Cation exchange synthesis of AgBiS2 quantum dots for highly efficient solar cells.

Silver bismuth sulfide (AgBiS2) nanocrystals have emerged as a promising eco-friendly, low-cost solar cell absorber material. Their direct synthesis often relies on the hot-injection method, requiring the application of high temperatures and vacuum for prolonged times. Here, we demonstrate an alternative synthetic approach via a cation exchange reaction. In the first-step, bis(stearoyl)sulfide is used as an air-stable sulfur precursor for the synthesis of small, monodisperse Ag2S nanocrystals at room-temperature. In a second step, bismuth cations are incorporated into the nanocrystal lattice to form ternary AgBiS2 nanocrystals, without altering their size and shape. When implemented into photovoltaic devices, AgBiS2 nanocrystals obtained by cation exchange reach power conversion efficiencies of up to 7.35%, demonstrating the efficacy of the new synthetic approach for the formation of high-quality, ternary semiconducting nanocrystals.

Preclinical Assessment of Enhanced Chemodynamic Therapy by an FeMnOx-Based Nanocarrier: Tumor-Microenvironment-Mediated Fenton Reaction and ROS-Induced Chemotherapeutic for Boosted Antitumor Activity.

In recent studies, iron-containing Fenton nanocatalysts have demonstrated significant promise for clinical use due to their effective antitumor activity and low cytotoxicity. A new approach was reported in this work utilizing cation exchange synthesis to fabricate FeMnOx nanoparticles (NPs) that boost Fenton reactions and responses to the tumor microenvironment (TME) for chemodynamic therapy (CDT) and chemotherapy (CT). Within the TME, the redox metal pair of Fe2+/Mn2+ helps break down endogenous hydrogen peroxide (H2O2) into very harmful hydroxyl radicals (•OH) while simultaneously deactivating glutathione (GSH) to boost CDT performance. To further enhance the therapeutic potential, FeMnOx NPs were encapsulated with thioketal-linked camptothecin (CPT-TK-COOH), a reactive oxygen species (ROS)-responsive prodrug, achieving a high CPT-loading capacity of up to 51.1%. Upon ROS generation through the Fenton reaction, the prodrug TK linkage was disrupted, releasing 80% of the CPT payload within 48 h. Notably, FeMnOx@CPT exhibited excellent dual-modal imaging capabilities, enabling magnetic resonance and fluorescence imaging for image-guided therapy. In vitro studies showed the cytocompatibility of FeMnOx NPs using MDA-Mb-231 and 4T1 cells, but in the presence of H2O2, they induced significant cytotoxicity, resulting in 80% cell death through CDT and CT effects. Upon intravenous administration, FeMnOx@CPT displayed remarkable tumor accumulation, which enhanced tumor suppression in xenografts through improved CDT and CT effects. Moreover, no significant adverse effects were observed in the FeMnOx NP-treated animals. In the current study, the FeMnOx@CPT anticancer platform, with its boosted •OH-producing capability and ROS-cleavable drug release, has been validated utilizing in vitro and animal studies, suggesting its capacity as a viable strategy for clinical trials.

Synthesis of oriented J type ZnIn2S4@CdIn2S4 heterojunction by controllable cation exchange for enhancing photocatalytic hydrogen evolution

Construction of semiconductor heterojunctions which promote the separation and transport of photogenerated carriers is an effective strategy for improving photocatalytic reaction efficiency. Based on the anisotropic electrical conductivity of layered ZnIn2S4 (ZIS) photocatalyst, an efficient heterojunction should be constructed along the layer plane of ZIS, that is, a J type heterojunction. However, achieving controllable synthesis of the oriented heterojunction of ZIS faces challenges. Herein, we develop a facile, cost-effective and spatially-selective cation exchange synthesis approach to construct J type ZnIn2S4@CdIn2S4 (J-ZIS@CIS) heterojunction using a flower-like hexagonal ZIS as the parent material. The developed synthesis approach can also control crystal structure of the heterojunction component CIS. This work presents a facile and controllable synthesis strategy to construct oriented anisotropic heterojunctions that are otherwise inaccessible. The as-prepared J-ZIS@CIS heterojunction displays a greatly enhanced photocatalytic hydrogen evolution activity with a rate of 183 μmol h−1, 2.77 times higher than that of pristine ZIS. Furthermore, the possible photocatalytic reaction mechanism is presented for the heterojunction.

Cation exchange synthesis of hollow-structured cadmium sulfide for efficient visible-light-driven photocatalytic hydrogen evolution

Efficient solar absorption and photoinduced charge separation are extremely important for solar-energy conversion on semiconductor photocatalysts. To advance the photocatalytic performance, we developed a general templated-assisted reverse cation exchange strategy to successfully synthesize hollow-structured CdS semiconductors with the textile structural surface. The crystal phase, particle morphology, optical/electrical properties, and photocatalytic performance of the as-syntheszied sample are investiagted by XRD, SEM, TEM, XPS, DSR, PL, ESR photoelectrochemical measurements, and Photocatalytic H2 evolution test. The final CdS sample exhibits an enhanced photocatalytic hydrogen evolution rate of up to 965 μmol·g−1 h−1, 2.8 times higher than the reported CdS nanorods. Based on the experimental and characterization results, the improved photocatalytic activity of the cadmium sulfide semiconductor can be ascribed to the special hollow cubic structure with a thin shell, which can enhance the light-harvesting ability and provide abundant photocatalytic active sites for facilitating the separation of photogenerated electron/hole pairs. This synthetic strategy may pave a new path for the rational design of efficient sulfur-based semiconductor photocatalysts for solar driven H2 production.

Cation Exchange Synthesis of Aliovalent Doped InP QDs and Their ZnSexS1-x Shell Coating for Enhanced Fluorescence Properties.

III-V quantum dots (QDs), in particular InP QDs, have emerged as high-performance and environmentally friendly candidates to replace cadmium based QDs. InP QDs exhibit properties of direct band gap structure, low toxicity, and high mobility, which make them suitable for high-performance optoelectronic applications. However, it is still challenging to precisely regulate the components and crystal structure of InP QDs, especially in the engineered stable aliovalent doping. In this work, we developed our original reverse cation exchange strategy to achieve Cu+ doped InP (InP:Cu) QDs at lower temperature. A ZnSexS1-x shell was then homogeneously grown on the InP:Cu QDs as the passivation shell. The as-prepared InP:Cu@ZnSexS1-x core-shell QDs exhibited better fluorescence properties with a photoluminescence quantum yield (PLQY) of 56.47%. Due to the existence of multiple luminous centers in the QDs, variable temperature-dependent fluorescence characteristics have been studied. The high photoluminescence characteristics in the near-infrared region indicate their potential applications in optoelectronic devices and biological fields.

Synthesis and Characterization of Sulfonated Magnetic Graphene-Based Cation Exchangers for the Removal of Methylene Blue from Aqueous Solutions

This article describes the synthesis, characterization, and performance of graphene-based magnetic cation exchangers as low-cost nanoadsorbers for the removal of methylene blue from aqueous solutions. The structure and surface morphology of the nanoadsorbers were characterized by X-ray diffraction, Fourier transform infrared, Raman, Brunauer–Emmett–Teller, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, high-resolution transmission electron microscopy, vibrating sample magnetometry, and thermogravimetric analysis. The effect of pH, incubation time, saturated adsorption capacities, and adsorption isotherms and kinetics on the adsorption of the sulfonated magnetic graphene oxide (SMGO) cation exchanger has been systematically studied. A comparative analysis of the samples was conducted with graphene oxide, sulfonated graphene oxide, and magnetic graphene oxide. Kinetic studies showed that adsorption followed a pseudo-second-order model, while the estimated maximum adsorption capacity using the Langmuir nonlinear isotherm was 246.47 mg g–1. Multiple regeneration and reuse experiments indicated that the SMGO performance remained above 80% after seven cycles of removal of cationic pollutants from aqueous solutions that could be applied to wastewater treatment.

Cation exchange synthesis of porous Cd1‐xZnxS twinned nanosheets for visible light highly active H2 evolution

AbstractEfficient charge separation is critical for the enhancement of photocatalytic activity for hydrogen generation. The porous Cd1‐xZnxS nanosheets with twinned phase junctions were synthesized by the cation‐exchange approach of inorganic‐organic hybrid ZnS‐diethylenetriamine nanoflakes with cadmium ions. With the synergy of the phase junctions induced by nano twins and porous structure, the hydrogen evolution average rate over the optimal sample Cd0.5Zn0.5S photocatalyst reaches 14.44 mmol h−1 g−1 without noble metal loading under visible light irradiation, corresponding to apparent quantum efficiency of 37.3% at 420 nm and solar‐to‐hydrogen energy conversion efficiency of 3.46%. On the one hand, twin‐induced phase junctions can improve the separation efficiency of photoelectron‐hole pairs, on the other hand, the large specific surface area ascribed to the porous nanosheet can effectively improve the light absorption capacity of photocatalysis, and provide more surface active sites. This study could provide a facile approach to design and fabricate advanced materials with porous twinned phase junctions for photocatalytic applications and optoelectronic devices.

Cation-Exchange Synthesis of Lead Bismuth Sulfide Quantum Dots and Nanorods for Thermoelectric Applications

Cation-Exchange Synthesis of Lead Bismuth Sulfide Quantum Dots and Nanorods for Thermoelectric Applications

Novel synthesis of natural cation exchange resin by crosslinking the sodium alginate as a natural polymer with 1,6-hexamethylene diisocyanate in inert solvents: Characteristics and applications

Novel synthesis of natural polymeric cation exchanger from sodium alginate reagent as natural polymer (CAlg-Na)n has been developed. This procedure takes place by crosslinking the solid sodium alginate with 1,6-hexamethylene diisocyanate (HDI) in dryness benzene as inert solvent (DB). The experimental results for crosslinking the alginate using different degrees of crosslinking of HDI/DB (w/w) showed that the capacity of the synthesized resin for binding the polyvalent metal ions reached its maximum at 30% of (HDI/D) ratio. This work aims to present a novel synthesis of cation exchange resin from natural polymers as an alternative promising competitor of low-cost, high performance and non-toxicity for removal of the toxic heavy metal ions in wastewater remediation and radionuclide pollutants from environmental contaminated media. The results obtained from various applied techniques for determining the bounded metal ion concentrations with (CAlg-Na)n indicated that the resin capacity was followed the order U(VI) > Cu(II) > Sr(II) > Ca(II) at 25 °C, respectively. The factors influenced the alginate affinity for chelating the metal ions were explained in some correlation terms between the alginate capacity and some physicochemical properties of chelated metal ions and its respective formed complexes. Speculated geometrical configurations for chelation were suggested and discussed.

Cation-exchange synthesis of PbSe/ZnSe hetero-nanobelts with enhanced near-infrared photoelectronic performance

To develop excellent photoelectronic and photovoltaic devices, a semiconductor with high photoelectron production efficiency and broad band absorption is urgently required. In this article, novel II-type PbSe/ZnSe hetero-nanobelts with enhanced near-infrared absorption have been synthesized via a facile strategy of a partial cation-exchange reaction and thermal treatment. Derived from ZnSe·0.5N2H4 nanobelts as templates, the belt-like morphology was preserved. Due to the mismatch of the crystal type and parameters between PbSe and ZnSe, the formed PbSe in the form of nanoparticles were separated out and decorated on the nanobelts. Furthermore, the composition ratio of Pb/Zn can be tuned through manipulating the adding amount of Pb2+ cations, the reaction temperature and time. The ultraviolet−visible−infrared diffuse spectra measurements suggest that the as-prepared PbSe/ZnSe hetero-nanobelts exhibited a broad band absorption from 300 to 1000 nm. In addition, they demonstrated excellent photoresponsivity in the same wavelength region and displayed a peak at approximately 840 nm. Finally, the enhanced photoelectronic sensing mechanism was discussed.

Synthesis and characterization of zirconium(IV) molybdosulphosalicylate, multi-walled carbon nanotubes and polypyrrole based ternary nanocomposites: Adsorption and lead sensing studies

The present paper reports the facile synthesis of zirconium molybdosulphosalicylate cation exchanger [Zr(IV)MoS] and its successive nanocomposites of polypyrrole bearing different weight percent of multiwalled carbon nanotubes (MWCNTs) using a simple sol-gel approach via in-situ oxidative polymerization (ZP, 1-ZMP and 2-ZMP having nil, 0.1 and 0.25 g MWCNTs respectively). The nanocomposites were systematically characterized by FTIR, SEM, TEM, XRD and TGA. The spectral data is indicative of the polymerization of pyrrole on the ZMP nanoparticles. The TEM images also signify the encapsulation of Zr(IV)MoS on pyrrole matrix while MWCNT appears as long threads. The TGA profiles of ZP, 1-ZMP and 2-ZMP are suggestive that as the loading of MWCNT is increased, the thermal stability also gets enhanced. ZP, 1-ZMP and 2-ZMP were also analysed for their adsorption behavior against Ni(II), Cu(II) and Pb(II) ions where maximum absorption efficiency was observed in the case of 1-ZMP nanocomposite. Similarly, the ZP, 1-ZMP and 2-ZMP nanocomposites were also screened for their probable lead sensing application using cyclic voltammetry and the possible mechanism of Pb2+ion detection in the presence of 2-ZMP was also explored.

Dark-Field Imaging of Cation Exchange Synthesis of Cu2-xS@Au2S@Au Nanoplates toward the Plasmonic Enhanced Hydrogen Evolution Reaction.

The development of novel electrocatalysts, especially Pt-free electrocatalysts, is of great significance for evolving hydrogen fuel cells. Two-dimensional materials have many advantages, such as large specific surface area, abundant active edges, and adjustable electronic structure, which provide broad prospects for studying high-performance electrocatalysts. In this paper, Cu2-xS@Au2S@Au nanoplates (NPs) were synthesized by cation exchange, which showed good catalytic performance toward the hydrogen evolution reaction (HER). Dark-field microscopy can help observe the process of cation exchange in real time to precisely control the synthesis of the composite materials. The synthesized Cu2-xS@Au2S@Au nanoplates (NPs) exhibited greatly enhanced plasmonic emission, resulting in accelerated chemical conversion and improved HER efficiency. Under 532 nm laser excitation, the overpotential of the HER shifted from 152 to 96 mV at a current density of -10 mA cm-2. The plasmonic nanocatalysts show exciting prospects in the field of new energy resources.

A telluride shell on plasmonic Au nanoparticles: amorphous/crystalline phase and shape evolution engineering via aqueous cation exchange

Using aqueous cation exchange synthesis strategy for the first time, we have synthesis Au@PbTe core–shell nanocrystals with engineering of amorphous/crystalline phase and shape evolution facilely.

SYNTHESIS AND PROPERTIES OF ION EXCHANGERS DERIVED FROM NON-WOOD CELLULOSE

A rational scheme for the processing of large-scale agro-industrial waste – walnut shells Juglans Regia L. and apricot kernels Prunus Armeniaca L. was proposed. At first stage, the raw material was delignificated using liquid ammonia to remove hemicelluloses and lignin. Isolated non-wood pulp is chemically modifying to increase sorption and ion exchange properties. For the synthesis of anion exchangers, cellulose was aminated using pyridine or trimethylamine after preliminary treatment consequentially with formalin and C2H5OH in HCl medium. As a result, we obtained high and weakly-basic ion exchangers with nitrogen content of 10.3–11.5% and high exchange capacity towards various classes of inorganic anions. For synthesis of cation exchangers, cellulose was treated with solution consisting of 20% H3PO4, 40% CO(NH2)2, and 40% H2O. Consequently, we obtained phosphorus-containing high-acidic cation exchangers with exchange capacity towards heavy metal of 5.5–8.6 mmol∙cm–3. Both types of ion exchangers have a high capacity towards uranium: anion exchanger – 4.25 mmol∙cm–3 and cation exchanger – 4.94 mmol∙cm–3, respectively. Average total yield of ion exchangers related to weight of air-dry feedstock was 90%. Synthesized ion exchangers characterized by IR spectroscopy. Presence of amine functional groups –NH2 in aminated cellulose and phosphate ester groups –OPO(OH)2 in phosphorylated cellulose was established. Specific surface area and total static exchange capacity of synthesized ion exchangers were established. An environmentally friendly method for the disposal of spent solutions from the synthesis of cation exchangers was proposed. It allows getting a liquid complex fertilizer containing 17% N and 13.9% P2O5. Usage of this fertilizer for grain crops feeding increases plants length by 40–75%, as well as overall biomass increase by 20–30%.

Cation-exchange synthesis and measurement of PbS quantum dots with high nonlinear optical properties

PbS quantum dots with nearly monodisperse size (∼3.8 nm) were successfully fabricated via a cation-exchange method, and were investigated by the z-scan technique with 532 nm laser radiation. The PbS quantum dots exhibited high optical nonlinearity with nonlinear absorption coefficient, nonlinear refractive index, and nonlinear susceptibility of 2.93 × 10−9 m/W, 1.12×10−9 esu, and 1.90 × 10-10 esu, respectively, and with optical limiting threshold value of 1.5 J/ cm2 under experimental conditions.

Synthesis of nanocrystalline bismuth ferrite by cation-exchange method

In the present work, cation-exchange synthesis on a previously synthesized organic matrix was used to obtain nanodispersed bismuth ferrite powder. The phase composition of the samples was investigated by X-ray diffraction. Using scanning electron microscopy images of powder particles were obtained, their morphology and size were studied. The ferromagnetic resonance in millimeter microwave frequencies at room temperature for multiferroic BiFeO3 nanopowder sample with an appropriate sample-thickness about 1 mm. was observed.

Cation exchange synthesis of two-dimensional vertical Cu2S/CdS heterojunctions for photovoltaic device applications

For the first time, two-dimensional vertical Cu2S/CdS heterojunctions with ultrathin thickness and large size were prepared by the cation exchange reaction for high-efficiency photovoltaic applications.

Cation-exchange synthesis of manganese vanadate nanosheets and its application in lithium-ion battery

Manganese vanadate (Mn2V2O7) 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(CH3COO)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 Mn2V2O7 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.

Perspective Wastewater Treatment from Cu2+ Ions in the Mining Industry

The synthesis of new cation-exchanger based on local raw materials for the extraction of copper from copper-containing solution investigated. A review of the literature regarding the problem of ion exchange method and the use of mine wastewater treatment process is presented. Sorption selectivity of Cu2+ ions by cation exchanger in the H-and Na-forms from dilute solutions was studied in the target concentration range 90 mg/dm3 and 5,49 g/ dm3. The full dynamic exchange capacity calculated. The cation exchanger analyzed with consideration for IR spectroscopic, chemical analysis, and scanning electron microscopic data. Quantum-chemical calculations performed that synthesized cation-exchanger stable complexes with Cu2+ ions. Obtained cation exchanger due to excellent behavior recommended removing copper ions from wastewater in the mine industry.