Sequential Ion Exchange Research Articles

Effect of the introduction of Zn on the electronic state of copper species in Cu-exchanged mordenite

This work evaluated the effect of Zn on the electronic state of copper in the Cu-Zn-mordenite binary system. The samples were prepared in two stages by sequential ion exchange of the initial sodium mordenite, using aqueous solutions of sulfate salts of these two metals, and changing the order of introduction of each of the cations, first Cu2+ and then Zn2+, or in the inverse order. The content of Zn and Cu changed within the 0.02–3.14 wt% interval at various Zn/Cu ratios. The prepared samples were characterized with UV–Vis spectroscopy in situ during temperature-programed oxidation (TPO) in oxygen, temperature-programed reduction (TPR) in hydrogen, and temperature-programed adsorption and desorption of NO (TPD). Cu and Zn have different affinities to mordenite, resulting in competition between them for zeolites sites, their redistribution, and formation of bimetallic Cu-O-Zn species. The order of ion-exchange makes it possible to modify the nature and the relative content of these metal species. Electronic properties of the resulting copper species strongly depend on both the Zn/Cu ratio and the order of exchange of metal ions. The knowledge we have obtained will be useful for designing of new effective catalysts based on copper-exchanged zeolites.

Compose and Convert: Controlling Shape and Chemical Composition of Self‐Organizing Nanocomposites

AbstractOrganizing the right material at the right place has the potential to revolutionize bottom‐up assembly of functional architectures. Despite tremendous progress, this is still difficult in particular because control over chemical composition and morphology are typically inherently entangled. Here a two‐step strategy is introduced based on self‐organization and conversion reactions to shape a wide selection of chemical compositions into user‐defined designs. First, photogeneration of CO2 induces precipitation of nanocomposites of barium carbonate nanocrystals and amorphous silica (BaCO3/SiO2) with control over shape and location following arbitrary illumination patterns. Second, the resulting nanocrystals are converted by sequential ion exchange into a palette of chemical compositions, while the original shape is preserved. By considering thermodynamic stability and chemical reactivity, orthogonal conversion reactions are designed for sequentially positioning nanocomposites of different metal chalcogenide semiconductors next to each other. Based on these strategies, different compositions are integrated into the same hybrid architecture, and the functionality potential is demonstrated by forming a light‐emitting perovskite semiconductor that is embedded into an optical waveguide. Combining light‐controlled self‐organization and shape‐preserving ion‐exchange reactions offers exciting opportunities for shaping up materials.

Abstract 3901: Therapeutic targeting of LGR5-positive cancer stem cells

Abstract Introduction: Destruction of cancer stem cells (CSC) is a major therapeutic goal. LGR5 marks active stem cells in many types of solid cancers. It has been very difficult to isolate good antibodies to native LGR5 and attempts to develop ADCs targeting LGR5 have not advanced. We took the alternative approach of using a natural LGR5 ligand to target monomethylauristatin (MMAE) to LGR5-expressing CSC. An Fc domain was fused to the LGR binding domains of RSPO1 and the sortase reaction was used to conjugate a Gly3-val/cit-PAB-MMAE linker at the C-terminal end to create FcF2-MMAE. We previously reported its efficacy in ovarian models here document its activity in other aggressive cancer models. Methods: FcF2-MMAE was produced by transient transfection in HEK293E cells and purified by a sequential Ni-NTA and ion exchange chromatography. OVCAR8 ovarian cancer cells were molecularly engineered to stably express an empty vector (OVCAR8/EV) or LGR5 (OVCAR8/LGR5.6) at a 10-fold higher level. The sortase A enzyme was produced in E. coli. Flow cytometry was used to quantify cell surface LGR5 in live cells using an anti-LGR5 antibody. Results: DEPMAP tools were used to identify cell types with high levels of WNT signaling that drives expression of LGR5. FCM confirmed LGR5 expression in colon LoVo, gastric AGS and neuroblastoma SKNAS cells. All three lines were very sensitive to FcF2-MMAE; GI50 values in 2D cultures were: LoVo 4.5, AGS 0.7 and SKNAS 8.6 nM. IC50 values for stem cell-derived spheroids grown from these lines were: 11.0, 3.0 and 1.70 nM, respectively. The MTD of FcF2-MMAE was found to be >1.5 nmol/g in mice. The plasma half-life was 29.7 h. A q7dx4 IP dose schedule was found to be more effective than a q4dx4 IP schedule. FcF2-MMAE inhibited in vivo SC growth in all 3 models at a dose of 1 nmol/g q7dx4, producing cures in a fraction of AGS tumors and delaying SKNAS growth >2-fold in the absence adverse events. In addition to MMAE, we showed that FcF2-His could be conjugated to the either deruxtecan or PNU159682; FcF2-His loaded with either one of these cytotoxins had low nM or sub nM cytotoxicity and retained the same high selectivity of FcF2-MMAE when tested in isogenic OVCAR8/EV and OVCAR8/LGR5 cells. Conclusions: FcF2-MMAE has activity in xenograft models of very aggressive tumors driven by high levels of WNT signaling (LoVo, AGS, and SKNAS) and LGR5 expression. Efficacy was obtained at doses well below its MTD indicating a wide therapeutic window. The FcF2 core accommodates multiple types of warheads without loss of targeting selectivity. The ability to switch out one cytotoxin for another provides versatility in targeting different diseases. FcF2-MMAE has advantages over ASCs. Its small size relative to antibodies favors better tumor penetration. The binding domains of RSPO1 also target stem cells expressing LGR4 and LGR6 as well as LGR5, something that cannot be achieved with an ADC. These features support the further development of FcF2-MMAE as a stem cell-targeted therapeutic. Citation Format: Maria Carmen Mulero, Catherine Rice, Sukshala A. Jahdav, Willie Pi, Alexander Lin, Mindy Nguyen, Owen Tai, Stephen B. Howell. Therapeutic targeting of LGR5-positive cancer stem cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3901.

Nanoscale chemomechanical variations of montmorillonite induced by the specificity of counterions—An in situ XRD and AFM study

The variable structural characteristics of montmorillonite (Mnt) in salt solutions depend not only on the quantity and distribution of the Mnt layer charge, but also on the specificity of counterions, including their radius, valence, concentration, and hydratability. In order to determine the nanoscale chemomechanical processes in a clay mineral–water–salt system, in situ X-ray diffraction (XRD) and atomic force microscopy (AFM) methods were used to investigate the structural variations of Mnt caused by different counterion species (e.g., Li+, Na+, K+, Rb+, Cs+, Mg2+, Ca2+, and Sr2+) at different concentrations (0.2–3.0 M). With an increasing concentration of counterions, separation of water molecules from the interlayer space of more weakly hydrated cations (Cs+, Rb+, and K+) is faster than for the more strongly hydrated cations (Li+, Na+, Mg2+, Ca2+, and Sr2+), water molecules are lost more slowly from the hydration shell, which remains stable even at high counterion concentrations. The sequential ion exchange in a monolayer Mnt observed by in situ AFM is consistent with the d(001) results from the real-time XRD analysis. Moreover, various defects on Mnt surfaces were visible in the high-resolution AFM images, which restrict the spatial arrangement of adsorbed cations. The water molecule partitioning between the interlayers in Mnt is controlled by the specificity of the counterions, and the cations can spontaneously form ordered structures on the surface of Mnt. These nonclassical interfacial phenomena occurred in the electric double layer (EDL) is controlled by the hydration of counterions, the surface structure and the charge distribution of Mnt.

Selective recovery of lithium from Dead Sea end brines using UBK10 ion exchange resin

AbstractThe Dead Sea, a live pool of minerals and elements, holds ~9% of the world's known lithium reserves. However, the low lithium concentrations (30–40 mg/L) in the end brine and the high divalent to lithium ratio (Mg+2 + Ca+2 to Li+) were obstacles that must be overcome to extract the lithium. In our previous work, lithium concentrations in the Dead Sea end brine were enriched by chemical precipitation up to 1700 mg/kg in the produced solid precipitate. The obtained precipitate was decomposed by double‐distilled water, and about 66% of lithium was leached, producing an environmental liquor containing an elevated concentration of lithium. A sequential ion exchange technique was used to achieve selective lithium recovery in this study. The ability of the UBK 10 strong acid‐type cation exchange resin (Na type) to remove lithium from simulated and environmental lithium‐bearing solutions was investigated. Because of the complex matrix comprising components that may compete with lithium adsorption, a greater quantity of adsorbent was required to achieve the equilibrium state for the environmental solution (7 g) compared to (3.6 g) for the simulated solution. For both lithium‐bearing solutions, the kinetics investigation revealed a pseudo‐second‐order tendency. The interfering capacity was determined to be 0.405, confirming the UBK 10 challenge to selective lithium adsorption. The divalent to lithium ratio was decreased by more than 50 times, yielding encouraging findings for extracting lithium from the low lithium—high divalent to lithium sophisticated Dead Sea end brines.

Synergistically Modulating Geometry and Electronic Structures of a Chalcogenide Photocatalyst via an Ion-Exchange Strategy.

Maneuvering the architecture and composition of semiconductors is essential to optimizing their performance in photocatalytic solar-to-fuel conversion. Here, we show that ion exchange, having a disparate mechanism with direct nucleation and growth of semiconductor crystals, can provide a new platform for rational control over the geometry and electronic structures of chalcogenide semiconductor photocatalysts. As a demonstration, the ZnSe nanocubes possessing a hollowed architecture and doped with a controllable amount of Ag+ ions are accessed via sequential ion exchange. The kinetics of the exchange reaction offers a knob for regulating the electronic structures of the Ag-doped ZnSe hollow cubes and, hence, their functions in light harvesting and photogenerated charge separation. Such synergistically geometric and optoelectronic modulation of ZnSe brings an order of magnitude enhancement in photocatalytic H2 evolution activity relative to commercial ZnSe powders. Our study corroborates that ion exchange may open up new horizons for judicious fabrication and engineering of semiconductor-based photocatalyst materials.

Insights into N-Coordinated Bimetallic Site Synergy during NO Selective Catalytic Reduction by CO.

The nature of the synergistic effect in bimetallic catalysts remains a challenging issue, due to the difficulty in understanding the adjacent interaction between dual metals at the atomic level. Herein, a CuFe-N/C catalyst featuring diatomic metal-nitrogen sites was prepared through a sequential ion exchange strategy and applied for NO selective catalytic reduction by CO (CO-SCR). The bimetallic CuFe-N/C catalyst exhibits high N2 selectivity with a NO conversion efficiency of nearly 100% over a wide temperature range from 225 to 400 °C, significantly higher than that of its single-component counterparts. The synergistic effect of bimetallic Cu-Fe sites is well revealed using the combined in situ FTIR technique and DFT calculations. Bifunctional Cu-Fe sites are demonstrated not only to provide two different preferential adsorption centers for the CO molecule and ONNO intermediate but also to achieve a complete electron cycle for efficient interfacial electron transfer upon ONNO uptake. The unique electron transfer mechanism stemmed from 4s-3d-type electron coupling, and different 3d shell fillings of Cu (3d10) and Fe (3d6) atoms are presented. These fundamental insights pave the way for the understanding of N-coordinated bimetallic site synergy and rational design of highly active atomic-scale metal catalysts for SCR applications.

Recent Advances in Catalysis Based on Transition Metals Supported on Zeolites.

This article reviews the current state and development of thermal catalytic processes using transition metals (TM) supported on zeolites (TM/Z), as well as the contribution of theoretical studies to understand the details of the catalytic processes. Structural features inherent to zeolites, and their corresponding properties such as ion exchange capacity, stable and very regular microporosity, the ability to create additional mesoporosity, as well as the potential chemical modification of their properties by isomorphic substitution of tetrahedral atoms in the crystal framework, make them unique catalyst carriers. New methods that modify zeolites, including sequential ion exchange, multiple isomorphic substitution, and the creation of hierarchically porous structures both during synthesis and in subsequent stages of post-synthetic processing, continue to be discovered. TM/Z catalysts can be applied to new processes such as CO2 capture/conversion, methane activation/conversion, selective catalytic NOx reduction (SCR-deNOx), catalytic depolymerization, biomass conversion and H2 production/storage.

Nutrient recovery from the digestate obtained by rumen fluid enhanced anaerobic co-digestion of sewage sludge and cattail: Precipitation by MgCl2 and ion exchange using zeolite

The aim of this study was to recover nutrients (NPK and other) from the liquid fraction of digestate obtained by rumen fluid enhanced anaerobic co-digestion of sewage sludge and cattail (Typha latifolia grass). Firstly, anaerobic digestion (AD) studies were performed to examine the biogas potential of selected substrates. The liquid fraction of digestate was then used in nutrient recovery experiments. Four methods were applied to recover nutrients: i) conventional struvite precipitation by MgCl2, ii) simultaneous precipitation and ion exchange by Na-zeolite, and iii) two-step recovery using precipitation, followed by ion exchange with powdered or iv) granulated Na-zeolite. The products of nutrient recovery were characterised using different chemical methods and the cress seed germination test was performed to evaluate their fertility potential.The results show that co-digestion of sewage sludge with cattail enhanced biogas production by almost 50 vol%. The addition of rumen fluid positively contributed to the degradation of lignocellulosic materials and to biogas production. In all of the recovery methods tested, phosphorus was successfully recovered with efficiency of more than 99 wt%. Nitrogen recovery was less efficient than phosphorus recovery, 85–92 wt%. Simultaneous precipitation and ion exchange lowered nitrogen recovery efficiency compared to classical struvite precipitation, while sequential precipitation and ion exchange resulted in improvement. The most efficient method was two-step recovery using granulated zeolite. The precipitates consisted of different Mg and K-phosphates in quite irregular shapes. The struvite and K-struvite were detected in low quantities. The precipitates contained more than 25 wt% of macronutrients (NPK), exhibited effective utilization of nutrients by plants, and showed good fertility potential. Precipitate mixed with powdered Na-zeolite promises to be interesting for further agricultural use, as zeolite offers several potential improvements for soil. Both zeolites exhibited good performance in the recovery of K+ ions.

Substitution of Ca2+ in Calcite by Sn2+ and Sr2+ cations through ion exchange characterized by X-ray absorption and photoelectron spectroscopies

Tin (Sn2+) and strontium (Sr2+), two potential alternatives to lead (Pb2+) in perovskite formation, were explored in transforming calcium carbonate (CaCO3) into a leaving group in a cation exchange reaction. This is the first part of a sequential ion exchange process in transforming calcite into a Pb-free perovskite material for perovskite solar cell applications. Calcite, a polymorph of CaCO3, was successfully transformed into strontianite (SrCO3) through a cation exchange reaction. In the Sn substitution reaction on the other hand, no SnCO3 formation was noted. Instead, oxides of Sn were formed. The wider spaces in between Ca2+ cations in (100) orientation account for the higher atomic Sn2+ and Sr2+ concentrations as compared to (001) orientation, where the cation movement is restricted. X-ray absorption and photoelectron spectroscopies were used to investigate the ion-exchange transformation of calcite towards the formation of an intermediate carbonate material.Graphic abstract

In-situ synthesis of ultrasmall Au nanoparticles on bimetallic metal-organic framework with enhanced electrochemical activity for estrone sensing

In this work, ultrasmall Au nanoparticles decorated bimetallic metal-organic framework (US Au NPs@AuZn-MOF) hybrids were facilely prepared by a sequential ion exchange and in-situ chemical reduction strategy. Numerous of Au nanoparticles with size less than 5 nm was homogeneously dispersed on the surface of the whole bimetallic AuZn-MOF polyhedrons. The integration of ultrasmall Au nanoparticles greatly enhanced the electron transfer capacity and electrochemical active surface area of the metal-organic framework host. Compared with the pristine Zn-MOF, bimetallic AuZn-MOF, the as-synthesized US Au NPs@AuZn-MOF hybrids exhibited remarkably promoted electrochemical activity toward the oxidation and sensing of endocrine-disrupting chemical (EDC) estrone. As a result, a highly sensitive electrochemical sensing platform was developed for the detection of estrone in the range of 0.05 μM–5 μM with limit of detection of 12.3 nM (S/N = 3) and sensitivity of 101.3 μA−1 μM−1 cm−2. Considering the structural diversity of MOFs and superior property of ultrasmall Au nanoparticles, the strategy proposed here may open a new avenue for the design and synthesis of other high-activity nanomaterials for electrochemical sensing or other challenging fields.

Bimetallic ions regulate pore size and chemistry of zeolites for selective adsorption of ethylene from ethane

The petrochemical industry currently accomplishes olefin/paraffin separation by energy-intensive cryogenic distillation at an enormous scale. We report a sequential Ca2+/Ag+ ion-exchanged zeolite that achieves nearly ideal molecular sieving of C2H4/C2H6 and superior C2H4 adsorption capacity. Sequential and partial ion exchange regulates the pore size in ±0.2 Å increments, ranging between 3.8 and 4.2 Å. The demonstrated C2H4 adsorption capacity of 3.7 mmol/g, under ambient conditions, is the highest among zeolite-based materials. Elaborated with DFT calculations, Ag+-induced the stretching of the C-H bond and reduction of H-C-H bond angle of the C2H4 molecule in confined pore, providing C2H4 with the molecular basis and favorable kinetics for selective admission to pore size even less than 4 Å. The strategy of using bimetallic ions to regulate pore aperture size and selective admission of gas molecules with favorable kinetics provides a general path to be extended to other analogous molecular separation processes.

Robust Anion Exchange Realized in Crystalline Metal Cyanamide Nanoparticles

Solution-mediated sequential ion exchange has emerged as a powerful yet simple technique to transform nanoparticulates into a complex architecture. However, the state-of-the-art demonstration of such fine-tailored nanostructures greatly relied on cation exchange reaction because it remains to be a great challenge to apply anion exchange without interfering the original morphology and crystallinity of the target particles. Herein, metal cyanamides with a looser cation sublattice enabled by the quasi-linear [NCN]2– anion units are discovered to be ideal parent compounds to accomplish robust anion exchange reactions. The complete conversion from metal cyanamide nanoparticles to metal chalcogenide nanoparticles (CdNCN to CdS, CdNCN to CdSe, and MnNCN to MnS) is successfully realized by low-temperature reaction in colloidal solution. The nanoparticles retain both the morphology and crystallinity throughout the entire exchange process. In-depth study reveals that the structural similarity in cation packing faci...

Boosting the charge storage of layered double hydroxides derived from carbon nanotube-tailored metal organic frameworks

Metal-organic frameworks derived nanoarchitectures attract considerable interests especially in electrochemical energy storage. However, controllably tuning crystal size with synchronously improving conductivity of metal-organic frameworks derived nanostructure is still the challenge for further capacity enhancement. Herein, we first conceive a strategy for the controllable synthesis of carboxylated carbon nanotubes connected hollow layered double hydroxides via sequential ion exchange of carboxylated carbon nanotubes-tailored metal-organic framework nanoarchitectures. By introducing the carboxylated carbon nanotubes, the derived hollow nanohybrids appear much smaller size and higher specific surface area, which is crucial to electrochemical reactions between electrolyte ions and electrodes. Owing to its well-designed structure and improved conductivity, the as-synthesized nanohybrids exhibit a significantly boosted specific capacity (855C g−1 at 1 A g−1) and unprecedented rate capability (91% capacity retention at 15 A g−1). When compared with the literature data by the “Ragone plots”, the hybrid supercapacitor assembled by as-synthesized nanaohybrids and active carbon demonstrates the extraordinary performance with a high energy density of 49.9 Wh kg−1 at a power density of 895 W kg−1. This novel strategy can stimulate the controllable synthesis of diverse metal-organic frameworks derived nanoarchitectures for energy storage, molecular adsorption, catalysis, drug delivery and separation towards sustainability.

A facile sequential ion exchange strategy to synthesize CoSe2/FeSe2 double-shelled hollow nanocuboids for the highly active and stable oxygen evolution reaction.

Transition metal-based nanostructures have been considered as promising substitutes for rare-earth metal oxide electrocatalysts toward the oxygen evolution reaction (OER). Herein, we report for the first time on a novel multicomponent metal selenide electrocatalyst based on CoSe2/FeSe2 double-shelled hollow nanocuboids (CoSe2/FeSe2 DS-HNCs) with the highly oxidative Co3+ species, which is synthesized via a facile sequential ion exchange strategy. The solid Co-precursor nanocuboids are first converted into the intermediate Co2[Fe(CN)6] with a mesoporous and double-shelled hollow structure produced through a facile ligand exchange at room temperature, and then the final CoSe2/FeSe2 DS-HNCs are obtained by a subsequent Se ion exchange reaction. The intermediate product of Co2[Fe(CN)6] plays an important role not only in constructing a double-shelled hollow structure but also in providing the Fe source for the growth of the final multicomponent metal selenides. Benefiting from the nanosized double-shelled hollow structure and mesoporous double-metal selenide shells with the highly oxidative Co3+ species, the as-prepared CoSe2/FeSe2 DS-HNCs exhibit superior OER performance to state-of-the-art metal selenides, including a small overpotential of 240 mV at a current density of 10 mA cm-2 and the excellent electrochemical durability over 50 h. This work opens up a new avenue towards developing highly active multicomponent noble-metal-free electrocatalysts.

Assessment removal of tritium radionuclide from liquid waste using sequential ion exchange resin

Assessment removal of tritium radionuclide from liquid waste using sequential ion exchange resin

One-Pot Synthesis of NiCo2S4 Hollow Spheres via Sequential Ion-Exchange as an Enhanced Oxygen Bifunctional Electrocatalyst in Alkaline Solution.

The oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) are considered to be cornerstones of many energy conversion and storage technologies. It is difficult studying high-performance nonprecious materials as cost-effective bifunctional electrocatalysts for both the OER and ORR in future practical applications. In this study, NiCo2S4 hollow spheres (NiCo2S4 HSs) were fabricated via an effective and facile one-pot "green" approach in an N, N-dimethylformamide-ethylene glycol binary solution. The obtained NiCo2S4 HSs had a high specific surface area as well as numerous active sites and showed a remarkable catalytic performance and durability toward both the OER and ORR in an alkaline electrolyte. For the ORR, NiCo2S4 HSs exhibited a positive half-wave potential of 0.80 V and demonstrated outstanding stability and enhanced methanol tolerance. For the OER, NiCo2S4 HSs presented a low overpotential (400 mV) at a current density of 10 mA cm-2, small Tafel slope, and excellent stability in 0.1 M KOH. Moreover, regarding the overall electrocatalytic activity, the potential difference of NiCo2S4 HSs was 0.83 V, surpassing that of NiCo2S4 nanoparticles, binary counterparts (CoS, NiS), and most highly active bifunctional catalysts described in the literature. The superior catalytic performance of NiCo2S4 HSs is mainly ascribed to its unique hollow structure, which increases molecular diffusion and adsorption, as well as the synergistic effect of Ni and Co, which offers richer redox reaction sites. Importantly, this strategy may facilitate the design and preparation of excellent bifunctional nonprecious metal electrocatalysts in various domains.

Formation of Hierarchical Cu-Doped CoSe2 Microboxes via Sequential Ion Exchange for High-Performance Sodium-Ion Batteries.

Electrode materials based on electrochemical conversion reactions have received considerable interest for high capacity anodes of sodium-ion batteries. However, their practical application is greatly hindered by the poor rate capability and rapid capacity fading. Tuning the structure at nanoscale and increasing the conductivity of these anode materials are two effective strategies to address these issues. Herein, a two-step ion-exchange method is developed to synthesize hierarchical Cu-doped CoSe2 microboxes assembled by ultrathin nanosheets using Co-Co Prussian blue analogue microcubes as the starting material. Benefitting from the structural and compositional advantages, these Cu-doped CoSe2 microboxes with improved conductivity exhibit enhanced sodium storage properties in terms of good rate capability and excellent cycling performance.

Formation of highly porous NiCo2S4 discs with enhanced pseudocapacitive properties through sequential ion-exchange

In this work, we have developed a sequential chemically topotactic transformation strategy to fabricate highly porous thin NiCo2S4 discs with complex crisscross pore channels through sequential in situ ion-exchange. Starting from Co3O4 discs prepared by direct pyrolysis of solid Co-glycolate discs, complex porous Co3S4 and NiCo2S4 discs are obtained after the sequential ion-exchange reactions with S2− and Ni2+ ions, respectively. Physicochemical and electrochemical investigations demonstrate that the as-derived NiCo2S4 discs with high electrical conductivity, ion-diffusion-derived large accessible surface area and pore volume present attractive pseudocapacitive properties including remarkably high capacitivity (908Fg−1 at 3Ag−1), good rate capability (610Fg−1 at 20Ag−1) and outstanding electrochemical stability with a capacitance retention of 82% after continuous cycling for 5000cycles. Furthermore, a hybrid device using the NiCo2S4 discs and carbon-based composite as positive and negative electrodes, respectively, delivers a high energy density of 42.7Whkg−1 at a power density of 375Wkg−1, suggesting that the NiCo2S4 discs could be a powerful electrode platform for advanced supercapacitors.

Confining SnS2 Ultrathin Nanosheets in Hollow Carbon Nanostructures for Efficient Capacitive Sodium Storage

Summary Tin disulfide (SnS 2 ) is a promising anode material for sodium-ion batteries because of its high specific capacity. However, the low conductivity and large volume change during reaction with Na + ions greatly limit its practical application. Herein, a multistep templating method has been exploited for the rational design and synthesis of SnS 2 nanosheets confined in carbon nanotubes (SnS 2 @CNTs). To demonstrate the universality of this method, SnS 2 nanosheets confined in carbon nanoboxes (SnS 2 @CNBs) and hollow carbon nanospheres (SnS 2 @CNSs) have also been synthesized by simply changing the template in the reaction system. Due to their unique structural merits, the SnS 2 @CNTs, SnS 2 @CNBs, and SnS 2 @CNSs show improved sodium storage performance in terms of high specific capacity, good cycling stability, and superior rate capability.