Dual Confinement Research Articles

Dual-confinement effect in metal oxide nanoparticles/MXene-reduced graphene oxide for high capacitive deionization performance

Metal oxide nanoparticles are one kind of important electrode materials for capacitive deionization (CDI) application. Unfortunately, most metal oxide materials usually exhibit poor electrical conductivity and often experience slow dissolution of metallic species, thereby resulting in limited desalination performance. Overcoming these obstacles still remains challenging due to the lack of synthetic approaches. Taking it into consideration, herein we proposed a dual confinement strategy to promote the CDI application of metal oxide nanoparticles. Nb2O5 was synthesized as a typical example for designing metal oxide/MXene-reduced graphene oxide (rGO) derived from Nb2CTx MXene/graphene oxide (GO) under hydrothermal condition. In the hybrid, Nb2CTx and rGO serve as both the confinement agent and conductive support for Nb2O5 nanoparticles, endowing Nb2O5/Nb2CTx-rGO with improved electronic conductivity and structural stability. As a result, the hybrid shows an outstanding desalination performance, including a NaCl adsorption capacity of 41.07 mg g−1, an ultra-fast average NaCl adsorption rate of 4.14 mg g−1 min−1 and excellent long-term cycling stability of 50 cycles (81 % desalination capacity retention rate). This work is expected to bring new insights in the synthesis of metal oxide materials for electrochemical desalination.

Boosting cobalt ditelluride quantum-rods anode materials for excellent potassium-ion storage via hierarchical physicochemical encapsulation

The exploration of anode materials that can store large-sized K-ion to solve the poor kinetics and large volume expansion issues has become the key scientific bottlenecks hindering the development of potassium-ion batteries (PIBs). Herein, ultrafine CoTe2 quantum rods physiochemically encapsulated by graphene and nitrogen-doped carbon (CoTe2@rGO@NC) are regarded as anode electrodes for PIBs. Dual physicochemical confinement and quantum size effect not only enhance electrochemical kinetics but also restrain large lattice stress during repeated K-ion insertion/extraction process. Superior electronic conductivity, K-ion adsorption, and diffusion ability can be acquired for CoTe2@rGO@NC, confirmed through first-principles calculations and kinetics study. K-ion insertion/extraction proceeds via a typical conversion mechanism relying on Co as the redox site, where the robust chemical bond of COCo plays an important role in maintaining the electrode stability. Accordingly, CoTe2@rGO@NC contributes a high initial capacity of 237.6 mAh·g−1 at 200 mA·g−1, a long lifetime over 500 cycles with low-capacity decay of 0.10% per cycle. This research will lay the materials science foundation for the construction of quantum-rod electrodes.

Experimental study on bond behavior between epoxy-coated reinforcement (ECR) and seawater sea-sand concrete (SSC) under FRP-steel confinement

This paper investigates the bond behavior between epoxy-coated reinforcement (ECR) and seawater sea-sand concrete (SSC) under dual confinement from fiber-reinforced polymer (FRP) and steel stirrups. The effects of various variables on failure modes, bond-slip curves and bond strengths were comprehensively discussed, including internal reinforcement type, concrete type, concrete cover, confinement type and confinement level. Test results show that the use of seawater and sea-sand in concrete is beneficial for the enhancement of bond strength compared with normal concrete, but the bond strength of SSC specimens with embedded ECR is found to be smaller than the counterparts with carbon steel reinforcement (CSR) due to the external epoxy coating on the bar surface. Besides, the bond strength is positively related to the concrete cover and confinement level regardless of other parameters. Finally, a new ultimate bond strength model considering the contribution of FRP-steel confinement is proposed based on theoretical analysis and good agreement between test results and theoretical predictions is achieved by the proposed model.

Confinement mechanism and compressive stress-strain behaviours of FRP-interlayer-steel confined concrete tubes

A fiber-reinforced polymer (FRP)-interlayer-steel confined concrete (FISC) column is formed by bonding the FRP material and a concrete-filled steel tube (CFST) with the grouting material, and it can improve the corrosion resistance and bearing capacity of CFST columns and avoid the early cracking of the epoxy resin in FRP confined concrete-filled steel tubes (CCFT). However, there are few researches on the compressive behaviours of FISC columns and the dual confinement on core concrete from the FRP tube and steel tube has not been expounded clearly. In this paper, twelve FISC specimens were tested under axial compression. The ratio of FRP and steel confining indexes and the concrete strength were the main parameters and the loading conditions (core CFST loading and whole section loading) were included. Failure patterns, load–axial shortening curves, and the strain development were analysed. In addition, the confining stresses of the FRP tube and steel tube were obtained, and it was found that the confinement on concrete could be divided into three stages of the non-confinement stage, the steel-controlling stage, and the FRP-controlling stage. In the FRP-controlling stage, the FRP confining pressure increased at a constant growth rate while the steel confinement was gradually weakened owning to the restraints of the interlayer grouting material. Furthermore, by regarding the concrete and grouting material as a whole unity, the axial stress-strain model of the confined concrete-grouting was developed, and the proposed model can predict the compressive stress-strain behaviours of an FISC column with good accuracy and simplicity.

Dual confinement of LaCoOx modified Co nanoparticles for superior and stable ammonia decomposition

In this work, we report the rational design of amorphous LaCoOx modified Co nanoparticles confined in both nitrogen-doped carbon (NC) matrix and two-dimensional (2D) mesoporous silica (LaCoOx/Co@NC/SBA-15(2D)) via in situ confined pyrolysis of nano-sized La doped ZIF-67 in the mesopores of SBA-15(2D) as a novel dual-spatially-confined composite catalyst with superior activity and stability toward ammonia decomposition to produce hydrogen. It achieves a NH3 conversion efficiency close to 100 % at a high gas hourly space velocity (GHSV) of 60,000 gcat-1 h-1 with an encouraging H2 production rate of 446 mmol gCo-1 min-1 at 600 ℃ and can maintain stable catalytic activity for 200 h, almost outperforming all Co-based catalysts reported so far. Various characterizations and theoretical calculation results reveal that the outstanding ammonia decomposition performance mainly origins from the dual-spatially-confined configuration, fully exposed active sites and high mass transfer efficiency, and the synergy of amorphous LaCoOx, Co nanoparticles and NC matrix.

Dual confining polysulfides by growing NiCo2S4 nanosheets on porous carbon nanoboxes to accelerate redox kinetics for efficient lithium-sulfur batteries

It is of particular significance to develop functional materials to regulate the polysulfide shuttling and promote the polysulfide conversion for lithium-sulfur (Li-S) batteries. Herein, we demonstrate the dual confinement of polysulfides on a composite host featuring NiCo2S4 nanosheets grown on porous carbon nanoboxes (CNB). The porous CNBs provide huge cavity for efficient accommodation of sulfur and physical confinement of soluble polysulfides. Meanwhile, the surface-grown NiCo2S4 nanosheets show strong chemical entrappment of polysulfides, and good catalytic effect on the polysulfide conversion. By virtue of the above dual effect on confining polysulfides, the sulfur cathode based on NiCo2S4/CNB host shows a high reversible capacity of 635.6 mAh g−1 at 5 C. Excellent cycle stability with a low capacity decay rate of 0.15% per cycle can be realized with a high sulfur loading of 4.8 mg cm−2 and an electrolyte/sulfur (E/S) ratio of 15 μL mgS−1. Moreover, the S/NiCo2S4/CNB cathode delivers a reversible capacity of 637 mAh g−1 at 1 C with a low E/S ratio of 3 μL mgS−1, as well as a good cycle stability. This work provide an effective strategy for fabricating sulfur hosts that enable a physical/chemical dual confinement of polysulfides for high-performance Li-S batteries.

Experimental and analytical study of square tubed concrete-encased cross-shaped steel (TCCS) columns under axial compression

This paper presents an experimental and analytical study on square tubed concrete-encased cross-shaped steel (TCCS) columns under axial compression. The effect of test variables covering the steel section types (Type B and L), steel tube thicknesses (2.75, 5.00 and 7.50 mm) and external CFRP layers (0, 1, 2 and 4) on the mechanical behavior of the specimens were investigated. The test results show that obvious local buckling of the flange is mainly observed in the specimens embedded with Type B steel section with a larger width-thickness ratio and severe concrete crushing is also detected in the corresponding position. The constraint provided by the flange of the Type B steel section in suppressing the lateral deformation of inner concrete is weaker than that of the Type L section, leading to the inferior behavior of load capacity, ductility, and energy absorption, whereas the impact of steel section type becomes less significant to the dilation behavior of TCCS columns with sufficient confinement provided by the external tube. Furthermore, the confinement mechanism of steel section confined concrete is interpreted based on the buckling theory, and the stress–strain model of confined concrete in TCCS columns is proposed by considering the dual confinement from external tube and steel section. Finally, an analytical model is developed to predict the load–strain relationship of TCCS columns according to the section analysis method. By comparing the predictions with the experiments in this paper and several existing literature, it can be found that the proposed analytical model possesses satisfactory accuracy and applicability.

Anchoring Metal‐Organic Framework‐Derived ZnTe@C onto Elastic Ti3C2Tx MXene with 0D/2D Dual Confinement for Ultrastable Potassium‐Ion Storage

AbstractThe prosperous deployments of renewable energy have stimulated the looming exploration of K‐ion batteries (KIBs) for grid‐scale energy storage because of their high energy density and low cost. However, lacking advanced anode materials with high theoretical capacity, fast K+ storage kinetics, and eco‐friendliness discourages KIB development. Here, for the first time, ZnTe as an advanced KIB anode material with a conversion reaction mechanism (yZnTe + xK+ + xe− → yZn + KxTey) is demonstrated. The ZnTe nanoparticles are uniformly dispersed in a carbon matrix using metal–organic frameworks as starting materials, which are subsequently anchored on Ti3C2Tx MXene nanosheets, forming elaborate ZnTe@C/Ti3C2Tx (ZCT) nanohybrids. Various theoretical modeling and postmortem examinations reveal the synergistic integrations between carbon and Ti3C2Tx. Compositionally, they regulate the electronic structure of ZnTe, providing fast K+ adsorption kinetics. Morphologically, they construct a 0D/2D dual confinement, addressing the volume change of ZnTe upon cycling. Therefore, the ZCT exhibits a high capacity (408.0 mA h g−1 at 0.1 A g−1) and excellent long‐term cyclability (230.2 mA h g−1 at 1.0 A g−1 after 3500 cycles), outperforming other reported transition‐metal‐chalcogenides. Significantly, the ZCT‐based full cells achieve a high energy density of 110.3 Wh Kg−1, making ZCT promising for practical applications.

A highly-efficient electrocatalyst for room temperature sodium-sulfur batteries: assembled nitrogen-doped hollow porous carbon spheres decorated with ultrafine α-MoC1-x nanoparticles

While room-temperature sodium-sulfur (RT Na-S) battery is considered one of the most promising technologies for next-generation energy storage, its commoditization is constrained by the shuttling and sluggish redox kinetics of the sulfur electrode. Herein, a honeycomb-like sulfur electrocatalyst with ultrafine α-MoC1-x nanoparticles uniformly distributed on nitrogen-doped hollow porous carbon spheres (MoC@NHC) is designed and synthesized. Prepared through a template-assisted strategy followed by a self-assembly and pyrolysis process, the interconnected hollow porous structure of MoC@NHC provides not only a microenvironment for confinement of sodium polysulfides (NaPSs) but also sufficient free space for accommodation of volume change during electrochemical cycling. Moreover, the polar α-MoC1-x nanoparticles coupled with N-doped carbon provides strong affinity to NaPSs and promote catalytic conversion of NaPSs, as confirmed by experimental results and theoretical calculations. Owing to the physical and chemical dual confinement effect and the fast conversion kinetics of NaPSs, the S/MoC@NHC-15 cathode demonstrates good rate performances (351.8 mAh g−1 at 10 C) and outstanding cyclability (retaining capacities of 418.4 and 312.6 mAh g−1 after 1000 cycles at 1 and 5 C, respectively). This study introduces a simple and effective method for fabrication of S/MoC@NHC cathode materials for high-performance RT Na-S batteries.

Boosting the deep oxidation of propane over zeolite encapsulated Rh-Mn bimetallic nanoclusters: Elucidating the role of confinement and synergy effects

Metal nanocluster catalysts with superior activity and stability are urgently needed in the deep oxidation of volatile organic compounds (VOCs). In this study, a novel silicalite-1 zeolite confined rhodium-manganese bimetallic nano-cluster (1.6 nm) catalyst (Rh-MnOx@S-1) was designed and prepared by a simple one-pot method using a dual confinement strategy (shell confinement and strong metal-metal oxide interaction) and applied in the deep oxidation of propane. The results revealed that the temperature at 90% conversion (T90) for propane over Rh-MnOx@S-1 was as low as 264 °C, which is evidently higher than the conventional supported (Rh-MnOx/S-1, T90 = 369 °C) and the MnOx-free (Rh@S-1, T90 = 285 °C) catalysts. Moreover, the turnover frequency (TOF) value of Rh-MnOx@S-1 at 220 °C was up to 16 × 10−3 s−1, which is approximately 5–6 times higher than those of comparable catalysts. Most importantly, Rh-MnOx@S-1 also exhibited excellent high temperature thermal stability, water resistance and recyclability, which can be attributed to the confinement effect of the zeolite shell and the synergistic electronic-structure interaction between the Rh and MnOx species. The in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) analysis indicates that the C3H8 deep oxidation mechanism over Rh-MnOx@S-1 catalyst follows the Mars-van Krevelen (MvK) mechanism, i.e., the adsorbed C3H8 species reacted with the activated oxygen species from Rh-MnOx interfaces. The dual confinement strategy developed in this study provides a new way to design high performance catalysts for the removal of VOCs under harsh reaction conditions.

Polymer nanoreactor mediated controllable synthesis of flexible semiconductor quantum dot nanofiber films

Semiconductor quantum dots (SQDs) find widespread applications, but manufacturing highly dispersed SQDs in films is a challenge. Herein, we report a polymer nanoreactor-mediated confinement strategy for the controllable synthesis of high-density and monodisperse ZrO2 SQDs nanofiber films. In detail, polyvinylpyrrolidone (PVP) is applied to confine zirconium acetate colloids through molecule steric hindrance effect in a water-based sol, which is then assembled into nanofibers by electrospinning. Afterwards, the PVP provides a fencelike spatial confinement in the nanofiber during calcining. With this dual domain confinement, high-loading (84.5 wt%) and monodisperse ZrO2 SQDs (∼4.47 nm) nanofiber film is prepared. The film exhibits superior flexibility and a high surface area of 1245 m2•g−1, as well as tunable light absorption from ultraviolet to visible-light, which breaks through the bottleneck of wide bandgap ZrO2 that can only be excited for photocatalysis under ultraviolet irradiation. This strategy opens new possibilities in large-scale manufacturing of high-quality SQD films for a series of potential applications.

Dual confinement strategy based on metal-organic frameworks to synthesize MnOx@ZrO2 catalysts for toluene catalytic oxidation

Active sites confinement is a promising way to enhance the activities of catalysts for volatile organic compounds decomposition (VOCs). However, the rational control of the active sites over composite catalysts raised challenges due to inevitably active sites’ aggregation into larger bulk particles during the pyrolysis. Here, we propose a dual-confinement strategy using metal–organic frameworks (MOFs) to fabricate well-dispersed MnOx@ZrO2 composite catalysts. These products have a distorted three-dimensional (3D) octahedral morphology with both Mn and Zr elements uniformly dispersed. Moreover, the agglomeration of Mn can be reduced through dual confinement. The crystal size of MnOx@ZrO2-NA is 17.65 nm, smaller than 1.17 μm of MnOx-ZrO2-cp and 125.73 nm of MnOx@ZrO2-A. Such MnOx@ZrO2-NA product exhibits a better catalytic ability of T50 = 248 °C than those of MnOx-ZrO2-cp (T50 = 295 °C) and MnOx@ZrO2-A (T50 = 280 °C). The increased Mn (III/Total) ratio, sufficient amount of adsorbed oxygen and good oxygen mobility from c-ZrO2 support play significant roles in the reaction mechanism. Further, a variety of MOx@ZrO2 (M = Co/Cu/Ce) composites with a similar nanostructure has been demonstrated. Therefore, this work can realize the high dispersion of active sites via the dual confinement, and provide a convenient route to synthesize potential catalysts for other pollutants control.

Effect of Internal Stirrups on the Eccentric Compression Behavior of FRP-Confined RC Columns Based on Finite-Element Analysis

Fiber-reinforced polymers (FRPs) have been widely used in the retrofitting and rehabilitation of reinforced concrete (RC) columns because they can provide substantial lateral confinement to concrete. Conventionally, the presence of internal stirrups is neglected in the retrofitting design due to a lack of understanding on the effect of internal hoops when both external FRP and internal steel confinement exist, particularly under eccentric loading. In this study, a finite-element (FE) method is developed to investigate the eccentric compression behavior of FRP-confined RC columns. A reliable concrete plastic-damage model that accurately considers the confining stiffness ratio between the FRP and steel is proposed for the first time, which facilitates the study of a difficult problem: the behavior of RC columns with the dual confinement system under eccentric loading. The accuracy of the model is verified by test results. An extensive parametric study of various affecting factors is carried out to investigate the confinement mechanisms of the concrete columns in terms of the axial stress and confining pressure distributions, lateral principal stress ratio, local stress–strain response, and interaction between the FRP/steel hoops and concrete. It is found that the nonuniform confining pressures under eccentric compression are significantly affected by the internal stirrups. With the existence of discrete transverse steel reinforcement, the axial resistance of the concrete core is increased, thereby improving the ultimate load capacity of the columns. An ultimate axial load model for RC columns that considered combined FRP–steel confinement is subsequently proposed. More accurate results are obtained using the proposed model compared with those calculated from existing design codes.

Strongly coupled Fe-doped NiS2/MoS2 composite for high-efficiency water splitting.

We developed a simple method to fabricate a strongly coupled Fe-doped NiS2/MoS2 composite by introducing dual confinement effects during the vapor vulcanization of precursors, which involves the controlled release of metal species and the in situ formation of an N-doped carbon layer. The Fe-doped NiS2/MoS2 composite exhibited a much-enhanced hydrogen/oxygen evolution reaction performance.

Dual confinement of high–loading enzymes within metal–organic frameworks for glucose sensor with enhanced cascade biocatalysis

The intrinsically fragile nature and leakage of the enzymes is a major obstacle for the commercial sensor of a continuous glucose monitoring system. Herein, a dual confinement effect is developed in a three dimensional (3D) nanocage-based zeolite imidazole framework (NC-ZIF), during which the high-loading enzymes can be well encapsulated with unusual bioactivity and stability. The shell of NC-ZIF sets the first confinement to prevent enzymes leakage, and the interior nanocage of NC-ZIF provides second confinement to immobilize enzymes and offers a spacious environment to maintain their conformational freedom. Moreover, the mesoporosity of the formed NC-ZIF can be precisely controlled, which can effectively enhance the mass transport. The resulted GOx/Hemin@NC-ZIF multi-enzymes system could not only realize rapid detection of glucose by colorimetric and electrochemical sensors with high catalytic cascade activity (with an 8.3-fold and 16-fold enhancements in comparison with free enzymes in solution, respectively), but also exhibit long-term stability, excellent selectivity and reusability. More importantly, the based wearable sweatband sensor measurement results showed a high correlation (>0.84, P < 0.001) with the levels measured by commercial glucometer. The reported dual confinement strategy opens up a window to immobilize enzymes with enhanced catalytic efficiency and stability for clinical-grade noninvasive continuous glucose sensor.

Composites of NiSe2@C hollow nanospheres wrapped with Ti3C2Tx MXene for synergistic enhanced sodium storage

Sodium-ion batteries (SIBs) have the virtues of abundant sodium source and low price, but the serious volume expansion and poor cycle stability caused by the large sodium ion radius limit its practical application. Herein, we develop a three-dimensional (3D) Ti3C2Tx MXene wrapped NiSe2@C hollow nanospheres (NiSe2@C@MXene) composites for advanced sodium ion storage. The electrostatic self-assembly of MXene on NiSe2@C hollow nanospheres not only provides dual structural confinement on carbon coated NiSe2, but also efficiently inhibits the self-stacking of MXene. Taking advantage of the highly conductive 3D hierarchical network, the NiSe2@C@MXene electrode is endowed with enhanced electrochemical activity, fast electrochemical dynamic and abundant spatially confined active sites, leading to high reversibility and stable structural integration. Consequently, the NiSe2@C@MXene electrode provides a synergistic enhanced capacity of 327 mA h g−1 at 2000 mA g−1 after 4000 cycles, indicating high-rate capability and long-term stability. This work provides a new route toward developing MXene engineered Ni-based electrode materials for high-performance sodium storage.

Controlled Water Uptake in Fuel Cell Membranes with Dual Chemistry Confinement

Nafion is one of the most commonly used materials for proton exchange membranes in polymer-electrolyte fuel cells (PEFC) due to its stability and high ion-transport capabilities. However, its dehydration problem as well as dimensional instability limits its application in high-temperature, low-humidity environments. In this paper, we propose a potential solution to this problem by introducing nanoscale confinements to the Nafion chains. In particular, a coarse grain molecular dynamics model is developed that reproduces the water absorption curve of the pristine Nafion membrane. The model enables us to perform systematic studies on the effects of confinement to the absorption behavior of the Nafion membrane at different activities. Confinement of different chemistries and sizes has been introduced in the simulation system in order to investigate its effects on water absorption on different activities. It is found that confinement of dual chemistry (consisting of both hydrophobic and hydrophilic confinements) offers a solution to its drawbacks. The hydrophobic confinement helps flatten the absorption curve and decrease the water absorption at high activity, while the hydrophilic confinement acts as a water reservoir, which increases the water absorption at low activity. The Nafion membrane with dual chemistry confinement in general has higher water absorption with smaller dimensional instability, which makes it suitable to operate in a high-temperature, low-humidity environment.

Dual Confinement of CoSe2 Nanorods with Polyphosphazene-Derived Heteroatom-Doped Carbon and Reduced Graphene Oxide for Potassium-Ion Batteries

High-capacity and highly stable anode materials are some of the keys to the realization of the application of potassium-ion batteries (PIBs). Cobalt diselenide (CoSe2) has been regarded as a high-potential anode material for PIBs. However, solving the problems of sluggish kinetics and large volumetric expansion during intercalation/deintercalation of K+ ions is always very challenging in terms of cobalt diselenide-based anode materials. Herein, reduced graphene oxide-encapsulated polyphosphazene-derived S, P, and N codoped carbon (SPNC)-coated CoSe2 nanorods (CoSe2⊂SPNC⊂rGO) were designed as PIB anode materials. CoSe2⊂SPNC⊂rGO delivers an excellent reversible capacity of 287.2 mAh g–1 at 100 mA g–1. Benefiting from the coating of heteroatom-doped carbon and encapsulation of rGO, the CoSe2⊂SPNC⊂rGO anodes exhibit a remarkable rate capability (100–1500 mA g–1 current density) and high stability (208.8 mAh g–1 after 500 cycles at 500 mA g–1). The results demonstrate that S, P, and N codoping in carbon layers provides active sites for K+ ion storage and increases the electrical conductivity. More importantly, the dual confinement of CoSe2 nanorods with carbon layers and rGO significantly reduced the volume expansion and kept the electrode structural integrity with repeating intercalation/deintercalation of K+ ions.

Study on the high-efficiency sympathetic cooling of mixed ion system with a large mass-to-charge ratio difference in a dual radio-frequency field by numerical simulations

This study proposes a method to achieve stable confinement and efficient sympathetic cooling of a mixed ion system in dual radiofrequency (RF) traps by numerical simulations. The dynamic coupling behavior, sympathetic cooling mechanism, and efficiency-affecting factors of the dual RF ion trap system were quantitatively analyzed by molecular dynamics simulations, yielding the stable confinement conditions of three-dimensional (3D) cold ion system in dual RF confinement fields and the characteristics of 3D correlation coupling between intrinsic micromotion and secular motion. The transient processes of ion intrinsic micromotion were also investigated. Herein, a reasonable second trapping potential contributed to the efficient cooling of the ion system and suppression of its micromotion. The effects of the dual RF trapping field strength on the spatial configuration and the dynamic coupling process of sympathetic cooling were investigated in mixed 3D ion crystals with a large mass-to-charge ratio (M/Q) difference, which reveals that simultaneous stable trapping and matching dynamic modes are the key to achieving efficient sympathetic cooling in the two-component ion system. These results are applicable to studies such as quantum logic manipulation, antimatter synthesis, dark ion detection, regulation of ultracold chemical reaction processes, and precision spectral measurements based on sympathetic cooling.

MOF-Derived CoSe2@N-Doped Carbon Matrix Confined in Hollow Mesoporous Carbon Nanospheres as High-Performance Anodes for Potassium-Ion Batteries

HighlightsA novel vacuum-assisted strategy is proposed to form N-doped carbon-encapsulated CoSe2 nanocrystals within hollow mesoporous carbon nanospheres (CoSe2@NC/HMCS) via a solid-state reaction.The “dual confinement” by both the N-doped carbon matrix derived from 2-methylimidazole and the small-sized pores of the hollow mesoporous carbon nanospheres can effectively prevent the overgrowth of CoSe2 nanocrystals.CoSe2@NC/HMCS exhibits an excellent electrochemical performance as the anode material for KIBs in terms of cycling stability and rate capability.