Yolk-shell Structure Research Articles

Improving Energy Density in Lithium-Ion Batteries Using Nanomaterials

Lithium-ion batteries are pivotal in modern energy storage, powering everything from consumer electronics to electric vehicles. Despite their advantages, current materials limit their energy density, particularly for electric vehicles. This paper explores the potential of nanomaterials to enhance lithium-ion battery performance, focusing on anodes, cathodes, and electrolytes. The study discusses the limitations of traditional graphite anodes and highlights nanostructured silicon and metal oxides as alternatives to significantly increase capacity and reduce volume expansion. For cathodes, it examines how nanomaterials like S-TiO2 yolk-shell structures and high-voltage cathode materials can improve energy density and stability. The role of nanostructured solid electrolytes in enhancing ionic conductivity and overall battery performance is also analyzed. The paper addresses the challenges of using nanomaterials, such as higher costs and the need for scalable production methods. It suggests future research directions, including optimizing nanostructures and developing cost-effective manufacturing processes. The findings underscore the potential of nanotechnology to overcome current limitations and significantly boost the energy density of lithium-ion batteries.

Enhanced solar-to-steam conversion efficiency using CuO-polyaniline yolk-shell structures

Herein, the low-cost copper oxide was encapsulated in the polyaniline (PANI) structure forming a yolk-shell (YS) platform which can provide a large surface area and sufficient active sites and enhance light scattering in its hollow space or voids, both of which can significantly improve the near-full usage of solar energy. The fabrication of the YS structure was assisted with a soft template (hexadecyltrimethylammonium bromide, CTAB) which the removed by the acidic etching process producing uniform voids through the composite structure. Moreover, the etching process using an acidic medium resulted in the formation of the PANI emeraldine salt which is beneficial for the salt-resistant properties of the composite. The encapsulated CuO@void@Es-PANI showed an outstanding rate of water evaporation of 1.91 kg m−2 h−1 and a corresponding high Solar-to-Steam conversion efficiency of 98.9 % under the irradiation of 1 sun compared to that of the normal mixed CuO/PANI (1.53 kg m−2 h−1 and 81.3 %). Meanwhile, the same high evaporation flux was approximately obtained after a continuous 72 h even in high saline water or contaminated seawater.

Boosting the Sodiation Kinetics of Sn Anode Using a Yolk-Shell Nanohybrid Structure for High-Rate and Ultrastable Sodium-Ion Batteries.

Metallic Sn (Tin) is a promising anode material for Na-ion batteries owing to its high theoretical capacity of 870mAhg-1. However, its large volumetric changes, interfacial instability, and sluggish sodiation kinetics limit its practical applications. Herein, a hierarchical yolk-shell nanohybrid composed of an Sn yolk and a Carbon/Silicon oxycarbide (C/SiOC) bilayer shell is prepared via the simple pyrolysis of a silicone oil dispersion containing an Sn precursor. The multifunctional bilayer helps boost sodiation kinetics by providing conductive pathways, enhancing the reversible capacity through surface capacitive reactions, and stabilizing the electrode/electrolyte interface. Abundant void interspaces inside the yolk-shell structure accommodate large volume changes of the Sn yolk. The Sn@C/SiOC nanohybrid demonstrates high specific capacity (≈500mAhg-1 at 1Ag-1), remarkable rate performance up to 10Ag-1, and ultrastable cyclability (91.1% retention after 1500 cycles at 5Ag-1). This yolk-shell nanohybrid structuring can guide the development of various high-capacity anodes for energy storage applications.

Yolk-Shell TiO2-NRs@SiO2 with enhanced photocatalytic hydrogen production

The efficiency of photocatalysis largely hinges on the design of the photocatalysts, which can be optimized for effective light absorption, improved charge separation and transport, and faster surface reactions. In this research, we developed a yolk-shell nanostructured photocatalyst featuring one-dimensional TiO2 nanorods (NRs) cores encapsulated within a porous silica shell. After photodepositing Pt nanoparticles (NPs) onto the TiO2-NRs, the photocatalyst exhibited excellent performance. Under simulated sunlight, Pt2-TiO2-NRs@SiO2 achieved a photocatalytic efficiency of 55.47 mmol g-1h−1 using methanol as the sacrificial agent and an apparent quantum efficiency (AQE) of 7.93 % at 350 nm, surpassing most previously reported TiO2-based catalysts. This superior activity is attributed to 1D NRs, along with the hollow structure that enhances light utilization through multiple scattering. The stability and high catalytic performance of these yolk-shell structures highlight the effectiveness of our design strategy in fabricating novel, highly active, and stable catalysts.

Localized surface plasmon resonance-enhanced photoelectrochemical immunoassay based on high-entropy yolk-shell Au@(ZnCdMnGaCu)xS

The yolk-shell structure has become a research hotspot in the field of photocatalysis in recent years due to its stability, movable yolk, and internal voids. However, yolk-shell has not been fully explored and applied in photoelectrochemical (PEC) immunoassays. In this work, a smartphone-based portable PEC immunoassay was constructed by using high-entropy yolk-shell Au@(ZnCdMnGaCu)xS as a photosensitive material, showing satisfactory detection with the assistance of localized surface plasmon resonance (LSPR). Specifically, a typical sandwich reaction introduces a detection antibody modified and labeled with gold nanoparticles (Au NPs) of alkaline phosphatase (ALP) into the system with the presence of prostate-specific antigen (PSA). Ascorbic acid (AA) content increased with increasing PSA and showed a linear enhancement of photocurrent at PSA concentrations of 0.01–50 ng mL−1 with a limit of detection of 8.94 pg mL−1. Additionally, the proposed assay technology not only provides a portable detection system for the immediate detection of tumor markers, but also offers a promising paradigm for the development of high-entropy materials.

Design of a yolk-shell ternary metal sulfide with a tunable structure for high-performance electromagnetic wave absorption.

Herein, we report a strategy for preparing a novel ternary metal sulfide (TMS) with a yolk-shell structure based on a "penetration-solidification-annealing" method. A series of FeCoNiSxGy with tunable structure, different morphology and composition was synthesized by adjusting the degree of sulfuration. Due to the synergistical manipulation of rich interface, defects, vacancies and electrical conductivity, as well as the unique yolk-shell structure, the appropriate sulfuration strategy achieved excellent impedance-matching and strong dielectric loss. The as-synthesized FeCoNiSxGy sulfides were blended with paraffin wax (under a filler loading of 30 wt%), which had the minimum reflection loss of -49.44 dB (2.20 mm) and the effective absorption bandwidth of 4.76 GHz (1.6 mm). In conclusion, this work could aid the design and regulation of a new type of ternary metal sulfides with high-performance electromagnetic wave absorption.

Internal Space Modulation of Yolk-Shell FeSe2@Carbon Anode with Peanut-Shaped Morphology Enabling Ultra-Stable and Fast Potassium-Ion Storage.

The poor cycling stability and rate performance of transition metal selenides (TMSs) are caused by their intrinsic low conductivity and poor structural stability, which hinders their application in potassium-ion batteries (PIBs). To address this issue, encapsulating TMSs within carbon nanoshells is considered a viable strategy. However, due to the lack and uncontrollability of internal void space, this structure cannot effectively mitigate the volume expansion induced by large K+, resulting in unsatisfactory electrochemical performance. Herein, peanut-shaped FeSe2@carbon yolk-shell capsules are prepared by modulation of the internal space. The active FeSe2 is encapsulated within a robust carbon shell and an optimal void space is retained between them. The outer carbon shell promotes electronic conductivity and avoids FeSe2 aggregation, while the internal void mitigates volume expansion and effectively ensures the structural integrity of the electrode. Consequently, the FeSe2@carbon anode demonstrates exceptional rate performance (242 mAh g-1 at 10 A g-1) and long cycling stability (350 mAh g-1 after 500 cycles at 1 A g-1). Furthermore, the effect of internal space modulation on electrochemical properties is elucidated. Meanwhile, ex situ characterizations elucidate the K+ storage mechanism. This work provides effective guidance for the design and the internal space modulation of advanced TMSs yolk-shell structures.

Heterointerface engineering of yolk-shell-structured Mn2O3/RuO2 for boosting oxygen electrocatalysis in rechargeable liquid and flexible zinc-air batteries

Rational construction of high-efficient bifunctional oxygen electrocatalysts is of crucial significance for rechargeable Zn-air batteries (ZABs). Here, the yolk-shell-structured Mn2O3/RuO2 heterojunction is purposely constructed via the Kirkendall effect as a robust bifunctional oxygen electrocatalyst for simultaneously driving oxygen evolution and reduction reactions (OER and ORR). The strong interactions between Mn2O3 and RuO2 induces the surface reconstruction that brings the electronic transfer from Mn to Ru, and the changes of coordination environments of metal atoms. Meanwhile, the yolk-shell structure enables maximum contact of the active sites with the electrolyte and prevents the dissolution and peroxidation of active species. As a result, the yolk-shell-structured Mn2O3/RuO2 shows an outstanding bifunctional activity with a very low potential gap of ΔE = 0.60 V. Moreover, the ZABs assembled with Mn2O3/RuO2 render a large open circuit voltage of 1.53 V, a high specific capacity of 742.1 mA h g−1 and an exceptional cycling stability over 850 h that significantly outperforms those of Pt/C+RuO2-based ZABs. Moreover, the self-made flexible solid-state ZAB with Mn2O3/RuO2 cathode also shows good charge–discharge reversibility and flexibility at different bending angles. This work provides a feasible method for the design of efficient oxygen electrocatalysts to promote the practical application of ZABs.

Pore engineering of Porous Materials: Effects and Applications.

Porous materials, characterized by their controllable pore size, high specific surface area, and controlled space functionality, have become cross-scale structures with microenvironment effects and multiple functions and have gained tremendous attention in the fields of catalysis, energy storage, and biomedicine. They have evolved from initial nanopores to multiscale pore-cavity designs with yolk-shell, multishells, or asymmetric structures, such as bottle-shaped, multichambered, and branching architectures. Various synthesis strategies have been developed for the interfacial engineering of porous structures, including bottom-up approaches by using liquid-liquid or liquid-solid interfaces "templating" and top-down approaches toward chemical tailoring of polymers with different cross-linking degrees, as well as interface transformation using the Oswald ripening, Kirkendall effect, or atomic diffusion and rearrangement methods. These techniques permit the design of functional porous materials with diverse microenvironment effects, such as the pore size effect, pore enrichment effect, pore isolation and synergistic effect, and pore local field enhancement effect, for enhanced applications. In this review, we delve into the bottom-up and top-down interfacial-oriented synthesis approaches of porous structures with advanced structures and microenvironment effects. We also discuss the recent progress in the applications of these collaborative effects and structure-activity relationships in the areas of catalysis, energy storage, electrochemical conversion, and biomedicine. Finally, we outline the persisting obstacles and prospective avenues in terms of controlled synthesis and functionalization of porous engineering. The perspectives proposed in this paper may contribute to promote wider applications in various interdisciplinary fields within the confined dimensions of porous structures.

Synthesis of ultra-high nitrogen doped hollow mesoporous carbon nanospheres via a universal solid–liquid interface self-assembly strategy

Functional mesoporous polymers, particularly their derived hollow mesoporous carbon spheres (HMCS), have introduced new opportunities in the field of energy storage. Traditional synthesis methods for HMCS typically rely on chemical etching, which often results in uniform chemical properties and structural control, thereby limiting their application in large-scale production and diverse fields. Therefore, in this study, we report a novel strategy for obtaining HMCS through the direct pyrolysis of a core matrix, melamine–formaldehyde resin (MF), to achieve hollow structures and ultra-high nitrogen doping (approximately 14.8 wt%). This new solid–liquid interfacial self-assembly approach enables the production of HMCS with remarkable electrochemical performance and practical application prospects in sodium-ion half-cells and full cells, thanks to the high nitrogen doping and unique structure. Notably, this strategy has been validated for its general applicability across 1D, 2D, and 3D solid matrices. Additionally, by adjusting the calcination temperature, this method allows for precise control over both the core size and nitrogen content of the egg yolk-shell structure mesoporous carbon spheres. In summary, the mesoporous materials developed in this study demonstrate flexibility, simplicity, versatility, and structural diversity, offering significant insights for future applications in energy storage and other fields.

A one-pot hydrothermal synthesis of morphologically controllable yolk-shell structured CoFe glycerate spheres for oxygen evolution reaction

CoFe-based catalysts are efficient electrocatalysts for the oxygen evolution reaction (OER) in alkaline media. Here, we present a simple one-pot hydrothermal method for synthesizing a series of CoFe glycerates with controllable surface morphologies and investigate their potential as highly efficient catalysts for the OER in alkaline media. These CoFe glycerates exhibit a unique yolk-shell microsphere structure assembled from ultrathin nanosheets. The adjustment of the surface nanosheet size is achieved by varying the CoFe ratio, ensuring a more efficient electrocatalytic system for the OER process. Due to the abundant active sites provided by the yolk-shell structure and interleaved ultrathin nanosheets, Co3Fe1 glycerate (Co3Fe1 gly) demonstrates a low overpotential (283 mV) and a small Tafel slope (44.61 mV dec−1) at 10 mA cm−2. Additionally, Co3Fe1 gly exhibits excellent durability in alkaline electrolytes. Moreover, a series of characterizations demonstrate that the active sites of Co3Fe1 gly are the high-valence Co species generated during the OER process. This study opens a promising avenue for utilizing efficient and low-cost electrocatalysts to enhance OER performance.

Antimony nanoparticles encapsulated in interconnected nitrogen-doped carbon nanospheres for high performances PIBs

Antimony (Sb) has attracted significant attention as an anode material for potassium-ion batteries (PIBs) due to its high theoretical capacity and suitable working voltage. However, the severe volume variations of Sb during potassiation/depotassiation process lead to sluggish kinetics and poor cyclic stability for PIBs. In this study, Sb nanoparticles are confined within interconnected N-doped carbon nanospheres (Sb@NC) through an effective carbothermal reduction process. The potassium storage performances and mechanism are elucidated through electrochemical tests combined with ex-XRD analysis. When used as an anode for PIBs, the optimized Sb@NC-2 anode exhibits excellent cycle stability of 463.0 mAh g−1 at 200 mA g−1 over 100 cycles and superior rate capability of 113.4 mAh g−1 at a high current density of 2 A g−1. Besides, a full cell comprising an Sb@NC-2 anode and a PTCDA cathode is also tested to validate the practical feasibility of the anode. Furthermore, Density Functional Theory (DFT) calculations demonstrate that N-doped carbon can enhance the adsorption of K+ and improve the kinetics of electrochemical reactions. Therefore, the unique yolk-shell structure in this study effectively restricts volume expansion and aggregation of Sb particles while facilitating rapid electron/ion transfer. These findings provide a potential alternative anode material for advanced PIBs.

Glucose-assisted solvothermal synthesis of hierarchical micro-nano yolk–shell V2O3 microspheres as an anode material for lithium-ion batteries

To accelerate the development of lithium-ion batteries (LIBs), researchers should urgently exploit next-generation electrodes with high specific capacity, long cycle stability, and excellent rate performance, such as TMOs, silicon-based materials, and alloys. Among all the modification measures, hierarchical micro-nano structure and yolk–shell structure are considered suitable and effective ways to improve the electrochemical performance of those novel materials. Herein, a facile glucose-assisted solvothermal method combined with heat treatment was implemented to synthesize hierarchical micro-nano yolk–shell V2O3. The special-structured material exhibited higher specific capacity, better structure stability, and faster electrochemical kinetics compared with nanosheet-structured and micro-nano-cluster-structured V2O3. When used as an anode for LIB, mnYS-V2O3 delivered high specific capacity of 650.1 ​mA ​h ​g−1 after over 500 cycles at a current density of 100 ​mA ​g−1, with a retention of 93.4 ​%. Moreover, the morphology evolution mechanism of micro-nano structure and yolk–shell structure was investigated in this work, which is beneficial to the design of other mnYS-structured TMOs.

The study on the reason why ZnS catalyst cannot suppress the shuttle effect of polysulfides in lithium-sulfur (Li–S) battery

The catalytic effect of zinc sulfide (ZnS) on the transformation of polysulfides (Li2S8) to lithium sulfide (Li2S) has been proven by the enhancement in the rate performance of lithium-sulfur (Li–S) batteries incorporating ZnS particles into the cathode. Accordingly, the shuttling effect of polysulfide should also be suppressed. However, the expected phenomenon is not found in the Li–S batteries with ZnS particles being added in the cathodes. In order to find the intrinsic mechanism of this phenomenon, detailed catalytic effects of ZnS particles on different polysulfide molecules are investigated. It is shown that ZnS can only enhance the reaction from Li2S4 to Li2S and it has almost no catalytic effect on the reaction from Li2S6 to Li2S4. This is why the shuttle effect of Li2S6 cannot be effectively prohibited. This mechanism is further verified via combining ZnS particles with S–C@PVA yolk-shell particles containing sulfur (S) and carbon black (C) as the core and PVA as the shell. Although the reaction from Li2S6 to Li2S4 cannot be directly catalysed by ZnS particles, it can still be enhanced when ZnS particles are distributed within the S–C@PVA yolk-shell structure (S–C–ZnS@PVA) because the reaction speed from the Li2S4 to Li2S is accelerated. The fast consumption of Li2S4 will result in the enhancement of the reaction from Li2S6 to Li2S4, which will largely reduce the diffusion of Li2S6 out of the PVA shell. While if ZnS particles are located outside the S–C@PVA yolk-shell structure (S–C@PVA-ZnS), large amount of Li2S6 can still diffuse out of the PVA shell and enter into the electrolyte since the transformation from is Li2S6 to Li2S4 relatively low. Both the rate performance and cycle stability of the batteries with S–C–ZnS@PVA cathodes are higher than those with S–C@PVA-ZnS ones. These results will give a guidance for the preparation of Li–S battery with high performance.

Boosting degradation of C4mim cation by metal alkoxide-derived Co4S3-activated Oxone: Yolk-Shell-Engineered enhancement and DFT-assisted toxic evaluation

The low bio-degradability of room-temperature ionic liquids (RTILs) makes RTILs a new class of persistent contaminants. It is urgent to develop useful technology to eliminate RTILs to prevent their presence in the environment. Sulfate-radical advanced oxidation processes (SR-AOPs) are particularly suitable for degrading such low-biodegradability pollutants. This study introduces a novel SR-AOP aimed at eliminating the representative RTIL, 1-butyl-3-methylimidazolium chloride (C4M), using an enhanced catalyst to activate Oxone. Traditionally, cobalt (Co) has been used for Oxone activation, but homogeneous catalysis with Co ions poses recovery challenges and secondary pollution risks. Recent studies suggest that cobalt sulfides (CSs) are more promising due to their superior redox properties, which are critical for effective Oxone activation. In this work, we developed a catalyst composed of cobalt sulfide (CS) with a unique yolk-shell (YS) structure, termed YSCS, to maximize catalytic activity. YSCS was easily fabricated from Co-Glycerate (CoG) precursors through a self-destruction/reconstruction process during sulfidization, resulting in a YS structure covered by self-assembled Co4S3 nanoplates. This morphology provides a highly mesoporous structure, enhanced electrochemical properties, and expanded active sites. Consequently, YSCS demonstrated significantly higher catalytic activity for Oxone activation compared to its precursor CoG and the benchmark Co3O4, with a reaction rate constant (k) of 0.108 min-1, surpassing those of Co3O4 NP + Oxone (0.007 min-1) and CoG + Oxone (0.023 min-1). Additionally, YSCS + Oxone exhibited a lower activation energy (Ea) of 17.8 kJ/mol for C4M degradation. The degradation pathway of C4M by YSCS + Oxone was thoroughly investigated using Fukui indices and analyzing the degradation by-products. Toxicity assessments showed that YSCS + Oxone significantly reduces the acute toxicity and bioconcentration factor of C4M, as well as potential mutagenicity and developmental toxicity risks. These findings confirm that YSCS is a highly effective catalyst for Oxone activation and RTIL degradation in water.

Dynamically regulated redox shuttling and nucleation of lithium polysulfides through the built-in ferroelectric field

Sulfur is highly desired for energy storage devices by virtue of its high theoretical specific capacity and natural abundance. Yet the lithium-sulfur battery becomes practically unstable due to the migration of lithium polysulfides (LiPSs), which is the major challenge for its widespread application. Here, we demonstrate that the polysulfide redox shuttling can be kinetically buffered, which relies on a rational design of ferroelectric/carbon interfaces in a silica-based host structure. In situ TEM observation shows that a robust sulfur host is constructed by spatially embedding ferroelectric BaTiO3 nanodots within both the shell and bulk of a yolk-shell microsphere. During the electrochemical cycling process, the as-prepared composite material functions as a LiPSs pocket. It facilitates the reversible LiPSs conversion, giving rise to long-term stabilization of lithium-sulfur battery. This is due to the synergetic effect of the built-in polarization electric field and abundant LiPSs nucleation sites at internal ferroelectric/carbon interfaces. Furthermore, we show that the nucleation and growth of Li2Sn can be regulated by the designed polarization electric field in the yolk-shell structure. This study further highlights the potential of physical field towards high-performance lithium-slfur batteries.

Hollow engineering and component optimization strategy to construct flower-like yolk-shell structure SiO2@Void@C@WS2 multicomponent nanocomposites for microwave absorption

Hollow engineering plays a crucial role in enhancing interfacial polarization, which is an essential factor in microwave absorption. Herein, an in-situ growth approach was adopted to successively coating C layer and WS2 nanosheets on the surface SiO2 nanosphere. The obtained results suggested that the formed SiO2@Void@C@WS2 multi-component nanocomposites (MCNCs) reveal a representative flower-like yolk-shell structure, which were manufactured massively through a simple channel. Additionally, the obtained SiO2@Void@C@WS2 MCNCs presented a more and more obvious yolk-shell structure and reduced WS2 content with decreasing the addition of SiO2@C or tungsten and sulfur sources. Because of their distinctive structures and remarkable cooperative effects, the SiO2@Void@C@WS2 displayed excellent microwave absorption performances. Through the majorization of hollow structure and WS2, improved properties of SiO2@Void@C@WS2 MCNCs could be acquired owing to their boosted polarization and conductive loss capabilities. Amongst, the resulting SiO2@Void@C@WS2 MCNCs exhibited the effective absorption band and minimum reflection loss values of 5.40 GHz and −45.50 dB with matching thicknesses of 1.78 and 1.55 mm, respectively. Therefore, our findings employed hollow engineering and optimization strategies for components to design and fabricate the yolk-shell structure flower-like MCNCs, which acted as highly efficient wide-band microwave absorbing materials.

Hollow engineering in CoNi@Air@C@MoS2 multicomponent composites derived from bimetallic CoNi Prussian blue analogs for ultra-wide bandwidth and strong electromagnetic wave absorption

In recent years, two-dimensional layered transition metal dichalcogenides-based multicomponent composites (MCCs) acting as electromagnetic wave (EMW) materials have received intensive investigations. However, the vulcanication of metal greatly hindered their enhancement of EMW absorption performances (EMWAPs). Herein, a combined metal-organic frameworks-derived and hydrothermal strategy was presented to produce yolk-shell structure (YSS) CoNi@Air@C@MoS2 MCCs. The results showed that the thermal and hydrothermal treatments resulted in the generation of YSS and two-dimensional MoS2 nanosheets, which maintained the original morphology of CoNi Prussian blue analogues. The protection of thick C layer well inhibited the vulcanization of inner CoNi alloy. The formed sheet-like MoS2 further optimized impedance matching characteristics, which led to the satisfactory EMWAPs of CoNi@Air@C@MoS2 MCCs. Furthermore, the EMWAPs could be further improved by optimizing the Ni:Co atom ratios CoNi@Air@C@MoS2 MCCs, which stemmed from their boosted impedance matching performances, EMW attention and polarization loss abilities. The absorption bandwidth and reflection loss values for YSS CoNi@Air@C@MoS2 MCCs are 8 GHz and −60.83 dB, which covered almost all C-Ku bands. In general, our research work provided a valid strategy to produce YSS magnetic CoNi@Air@C@MoS2 MCCs with high efficiency, which well avoided the vulcanization of metal nanoparticles, made best of hollow engineering and atomic ratio optimization strategy to boost the comprehensive EMWAPs.

Yolk-shell MOF-on-MOF hybrid solid-phase microextraction coatings for efficient enrichment and detection of pesticides: Structural regulation cause performance differences

Metal-organic frameworks (MOFs) based composites with different structure-activity relationships have been widely used in the field of organic pollutant adsorption and extraction. Here, two MOF-on-MOF composites with different structures (yolk-shell and core-shell) from homologous sources were prepared by a simple in-situ growth synthesis method and structural regulation. In order to verify the effect of composite structure on the extraction capacity, the adsorption performance of the yolk-shell structure (YS–NH2-UiO-66@CoZn-ZIF) and the core-shell structured (NH2-UiO-66@CoZn-ZIF) material were compared by using them as coating material of direct immersion solid-phase microextraction (DI-SPME) to enrich six pesticides in five matrices. The results showed that because of the unique hollow hierarchical structure, high specific surface area (930.68 m2 g−1), abundant and open active sites, and synergistic and complementary adsorption forces, YS-NH2-UiO-66@CoZn-ZIF composites had the maximum adsorption amount of 36.01–66.31 mg g−1 under the same experiment condition, which was 6.81%–34.26 % higher than that of NH2-UiO-66@CoZn-ZIF. In addition, the adsorption mechanism of the prepared materials was verified and elaborated through theoretical simulations and material characterization. Under the optimized conditions, the YS-NH2-UiO-66@CoZn-ZIF-coated SPME-HPLC-UV method had a wide linear range (0.241–500 μg L−1), a good linear correlation coefficient (R2 > 0.9988), a low detection limits (0.072–0.567 μg L−1, S/N = 3) and low quantification limits (0.241–1.891 μg L−1, S/N = 10). The relative standard deviations of individual fibers and different batches of fibers were 0.47–6.20 % and 0.22–2.48 %, respectively, and individual fibers could be recycled more than 104 times. This work provided a good synthetic route and comparative ideas for exploring the in-situ growth synthesis of yolk-shell composites with reasonable structure-activity relationships.

In-situ synthesis of yolk-shell Si/C anodes via ZnO transformation for high rate lithium-ion batteries

The conceptual design of yolk-shell structured Si/C composite materials is considered an effective approach to enhancing the structural stability of silicon-based anode materials over long cycles. Here, for the first time, zinc oxide is used as both the internal sacrificial layer and the external coating layer reactant, allowing it to be transformed into voids and the carbon layer precursor during subsequent operations. These internal voids can buffer the volume expansion of silicon, ensuring the electrode's integrity during cycling. The ZIF layer formed through in-situ solvothermal reactions can effectively reduce the occurrence of isolated ZIF in the solvent, resulting in better coating of the nano‑silicon particles. Compared to traditional processes for preparing yolk-shell structures, this gentle synthesis strategy avoids the use of HF, offering a new direction for large-scale production. This optimized yolk-shell Si/C-0.70 M electrode exhibits excellent rate performance (specific capacity of 988 mA h g−1 at a high current density of 2 A g−1) and long-term cycling stability (specific capacity of 722 mA h g−1 after 300 cycles at a current density of 0.5 A g−1; reversible specific capacity of 557 mA h g−1 after 500 cycles). Therefore, this scalable study offers a new approach for safely producing yolk-shell anode materials with high cycle stability on a large scale.