Yolk-shell Microspheres Research Articles

Anchoring Ni atomic clusters on yolk-shell In2O3 microspheres for highly sensitive, ultra-rapid responding/recovering ppb-level NO2 detections

Highly sensitive, sophisticated and rapidly responding/recovering NO2 sensors are of a pressing demand across various modern applications. However, traditional metal oxide semiconductors (MOSs), such as In2O3, often grapple with issues such as diminished sensitivity and tardy responding/recovering. To address these challenges, we present a novel, simultaneous enhancement strategy centered around Ni atomic clusters (NiAC) integrated into In2O3 yolk-shell microspheres. This innovative structural and compositional design not only enhances NO2 adsorption thermodynamics but also improves kinetics reacting rate. The optimized heterostructured NiAC-In2O3 exhibits exceptional NO2 sensing performances with high response (454.62 to 10 ppm NO2), instantaneous responding/recovering dynamics (1/3 s), and an impressively ultra-low detection limit (1 ppb) at 200 ℃. Reaction kinetics calculation, finite element method (FEM) simulations and further validation through In-situ diffuse reflection infrared Fourier transform spectroscopy (In-situ DRIFTS) and temperature-programmed desorption (TPD) analyses confirms the accelerated NO2 adsorption/desorption dynamics, enhanced NO2 dissociation and trace-concentration NO2 molecule capturing capability attributed to NiAC. Considering these merits, The fabricated NiAC-In2O3 ensures high-precise, instantaneous, ppb-level NO2 detections.

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.

Multiple heteroatom-doped cobalt sulfoselenide@C yolk-shell microsphere as excellent anode materials for sodium-ion batteries and their conversion reaction mechanism with sodium ions

To address the sluggish reaction kinetics commonly associated with the transition metal chalcogenide anodes in their interaction with alkali metal ions, introducing heterostructures into these materials is proposed as a novel approach. Herein, we introduce a fabrication method for yolk-shell structured microsphere comprising heteroatom-doped cobalt sulfoselenide nanocrystals using a recycled solution. The prepared material demonstrates a composition of sulfur-doped cobalt selenide, forming hetero-anion metal compounds. A detailed study of the reaction mechanism in cobalt sulfoselenide reveals the formation of Na2S/Na2Se heterointerfaces during the conversion reaction, which facilitate a rapid diffusion of Na-ions. Furthermore, heteroatom doping in the cobalt sulfoselenide nanocrystals, induced by cobalt recycling process, leads to the lattice expansion, further enhancing the Na-ion diffusion kinetics. Additionally, through an infiltration of pitch solution and a simple heat-treatment, pitch-derived carbon is coated on the cobalt sulfoselenide nanocrystals. This carbon layer can effectively accommodate the volumetric stress during repeated cycling, enhancing the stability. Consequently, carbon-coated heteroatom-doped cobalt sulfoselenide yolk-shell microsphere anode exhibits stable cycling stability (560 mA h g−1 for 100 cycles at 0.2 A g−1) as well as great rate capability (140 mA h g−1 at 15 A g−1) for sodium-ion batteries (SIBs).

Copper Vanadium Oxide Yolk-Shell Microspheres with Excellent Capacitance and Cycling Performance for Electrochromic Supercapacitor.

Vanadium pentoxide (V2O5) is considered a promising material for electrochromic supercapacitors due to its rich color transitions and excellent electrochemical capacity. However, V2O5 exhibits low electrical conductivity, and its volume changes dramatically during charge-discharge cycles, leading to structural collapse and poor long-term cyclability. These issues have hindered the development and application of V2O5. In this study, copper vanadium oxide yolk-shell microspheres (CVO) were synthesized through a one-step solvent heat treatment with an annealing process. With the doping of copper element, the capacitance, conductivity, and cyclic stability of CVO microspheres were significantly enhanced. Subsequently, the sphere-wire network structure was formed by blending Na2V6O16·3H2O nanowires (NVO), resulting in the formation of CVO/NVO composites. The three-dimensional sphere-wire network efficiently facilitates the acquisition of additional redox sites and strengthens the material-to-substrate bonding. Under the combined influence of these favorable factors, CVO/NVO achieved a high specific capacitance of 39.2 mF cm-2, with a capacitance retention of 84% after 7500 cycles at a current density of 0.7 mA cm-2. The fully inorganic solid-state electrochromic supercapacitor (ECSC), assembled on the basis of CVO/NVO, demonstrates a vivid and clearly distinguishable color change (ΔE* = 37). Even more impressive is the energy storage capacity (18.4 mF·cm-2) and the cycling stability (up to 89% retention after 10,000 cycles) exhibited by the devices. These key performances are superior to those of most of the previously reported V2O5-based ECSCs, opening a promising avenue for the development of V2O5-based electrochromic energy storage devices.

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.

Fabrication of heteroatom-doped cobalt oxide yolk–shell microsphere using recycled solution from waste materials and their excellent electrochemical properties as an anode material for lithium-ion batteries

Fabrication of heteroatom-doped cobalt oxide yolk–shell microsphere using recycled solution from waste materials and their excellent electrochemical properties as an anode material for lithium-ion batteries

Yolk-shell microspheres perovskite Gd/Fe oxides with rich oxygen vacancies for ultra-sensitive properties in acetone detection

Acetone as a toxic and hazardous gas is widely appeared in life. In this paper, p-type Gd/Fe oxide yolk-shell microspheres were prepared by a one-step hydrothermal method. Characterization and test results shows that perovskite Gd/Fe oxides with yolk-shell microspheres possess abundant oxygen vacancies, which presents excellent acetone gas-sensitive performance. Among the obtained sensor, the optimal operating temperature of the S-4 (Gd0.77/Fe) sensor is reduced to 200 ℃, and the response value (S = 20) to 100 ppm acetone is improved by 5 times (compare to S-1). The lowest detection limit can be as low as 0.5 ppm, furthermore the sensor presents resist-humidity. Electron paramagnetic resonance (EPR) and x-ray photoelectron spectroscopy (XPS) results reveal that the ratio of Gd/Fe has a strong correlation with the content of oxygen vacancies. The rich oxygen vacancies control theory is the main reason for improving gas sensing performance in this work. The presence of oxygen vacancies effectively increases the active sites and further promotes intermolecular interactions. Overall, the sensor S-4 (Gd0.77/Fe) has an important potential in the detection of acetone in human breath with high response and low detection limit under high humidity environment.

Hierarchical ZnO/ZnFe2O4 yolk-shell adsorbent as a promising material for phosphate recovery and adsorption of organic pollutants from the simulated wastewater

Mitigation of phosphate contamination is essential to preserve the health and integrity of the water ecosystem. Therefore, to prevent eutrophication and preserve water resources, it is essential to establish an effective and long-lasting phosphate removal process. Herein, a highly efficient and eco-friendly ZnO/ZnFe2O4 (ZZFO) yolk-shell microsphere was designed by the glycothermal method followed by calcination for phosphate removal and adsorption of Congo red (CR) organic dye aqueous solution. ZZFO demonstrated an outstanding Langmuir hypothetical optimum phosphate adsorption ability of 103.2 mg-P/g in batch phosphate adsorption studies. This value is 5.54 and 8 times higher than that of pristine ZnO and Fe2O3, respectively, and the adsorbent was readily removed with the use of an external magnetic field. The anions experiments showed that, except chlorine and fluoride ions, other regular anions have a slight influence on the phosphate adsorption process. The Langmuir and pseudo-second-order model showed excellent correlation constants. Moreover, ZZFO exhibited the capability to adsorb CR aqueous solution, which is a significant finding for aquatic remediation. Our experimental findings have significant implications for the fabrication of sustainable adsorbents for the treatment of wastewater.

Novel ZnWO4 yolk–shell microspheres: interface regulation and high removal efficiency for Pb2+

Hierarchical nanoflake-assembled hierarchical ZnWO4 yolk–shell microspheres were prepared and exhibited superior adsorption efficiency for Pb2+.

Constructing magnetic/dielectric dual loss and phonon/electron thermal carriers γ-Al2O3-based yolk-shell microspheres to collaboratively advance microwave absorption and heat conduction.

The severe electromagnetic (EM) interference and overheating issues in 5G/6G electric devices increasingly heighten the need for developing multifunctional materials with large heat conduction (HC) and high EM wave (EMW) absorption. Here, a series of γ-Al2O3-based yolk-shell microspheres (γ-AlOOH, γ-Al2O3, γ-Al2O3@C, γ-Al2O3@Fe3O4@C, and γ-Al2O3@FeAl2O4@Fe@C YSMSs) as multifunctional fillers are investigated for the simultaneous improvement in the HC and EMW absorption of γ-Al2O3-based composites. Using γ-AlOOH YSMSs as precursors produced from a hydrothermal method, the γ-Al2O3-based YSMSs were synthesized via an annealing route or soaking-annealing route; their phases, textures, and compositions were finely adjusted by changing the Al3+/Fe3+ molar ratio (β) and annealing temperature (Ta). Results show that the thermal transfers in the γ-Al2O3-based YSMSs are promoted by the synergic effect of phonons and electrons when they are utilized as thermally conductive fillers. Comparatively, the γ-Al2O3@FeAl2O4@Fe@C YSMSs formed at β = 8 : 2 and Ta = 700 °C exhibit a high HC of 1.84-3.29 W m-1 K-1 in a loading amount of 5-40%, exceeding those of not merely γ-Al2O3, γ-AlOOH, γ-Al2O3@C, and γ-Al2O3@Fe3O4@C YSMSs but also most previously reported fillers. Furthermore, the γ-Al2O3@Fe3O4@C YSMSs exhibit prominent EMW absorption properties with a large ABW/d of 4.49 GHz mm-1 (just 30% loading), superior to most other Al2O3-based absorbers. Such excellent EMW absorption could be explained by magnetic/dielectric dual loss and significant cavity and interfacial effects caused by yolk-shell structures. In conclusion, this work inspires the development of yolk-shell structures with magnetic/dielectric dual loss and phonon/electron thermal carriers as high-performance bifunctional materials with exceptional heat conduction and EMW absorption.

Synthesis of Carbon Coated Nickel Cobalt Sulfide Yolk-shell Microsphere and Their Application as Anode Materials for Sodium Ion Batteries

Synthesis of Carbon Coated Nickel Cobalt Sulfide Yolk-shell Microsphere and Their Application as Anode Materials for Sodium Ion Batteries

Preparation of cassava starch-gelatin yolk-shell microspheres by water-in-water emulsion method

This paper reports the preparation and characterization of gelatin-cassava starch microspheres using the water-in-water emulsion technique. The effects of different weight ratios (10: 0, 9: 1, 8: 2, 7: 3, 6: 4, 5: 5) of starch to gelatin on the morphology, structure, thermal properties, and stability of microspheres were investigated. The morphology results showed that most microspheres had spherical shapes and smooth surfaces. When the weight ratio of starch to gelatin was 5: 5, the prepared microspheres formed a stable yolk-shell structure. The swelling capacity of the microspheres increased with the proportion of gelatin, up to 682.3 %. The gelatin and starch in the microspheres were compatible but not miscible. Compared with the native starch, the crystalline structure of microspheres changed from A-type to a mixture of B-type and V-type, and the relative crystallinity decreased. Differential scanning calorimetry results showed that the melting of microspheres involved both gelatin dissolution and starch gelatinization. Due to the formation of composite microspheres, the starch content decreased, and the release of reducing sugars from the microspheres upon hydrolysis was reduced. The gelatin-cassava starch microspheres are simple to prepare, biocompatible, and can be used as a potential material for microencapsulation.

Hollow Mn–Co–O@C Yolk–Shell Microspheres with Carbon Shells as Cathodes Derived from a Double-Metal MOF for Aqueous Zinc-Ion Batteries

Hollow Mn–Co–O@C Yolk–Shell Microspheres with Carbon Shells as Cathodes Derived from a Double-Metal MOF for Aqueous Zinc-Ion Batteries

Modulating zinc metal reversibility by confined antifluctuator film for durable and dendrite-free zinc ion batteries.

Aqueous Zn ion batteries (ZIBs) are promising systems due to their intrinsic safety, low cost and non-toxicity, and the Zn corrosion and dendrite growth will cause the poor reversibility of Zn anode. Herein, we developed the porous Zn@C solid, hollow and yolk-shell microspheres film as Zn anode antifluctuator (ZAAF). The prepared yolk-shell microspheres (ZCYSM) film with superior buffering can effectively restrict the deposition of Zn metal in its interior and inhibit the volume expansion during plating/stripping process, thus modulating the Zn2+ flux and enabling stable Zn cycling. As a proof of concept, the ZCYSM@Zn symmetric cells achieve the excellent cyclic stability over 4,000h and cumulative plated capacity of 4 Ah cm-2 at a high current density of 10mA cm-2 . Concomitantly, the suppressed corrosion reactions and dendrite-free ZAAF significantly improve the durability of full cells (coupled to CaV6 O16 ·3H2 O). Additionally, we integrate durable pouch cell and electrochemical neuromorphic inorganic device (ENIDe) to simulate neural network, providing a strategy for extreme interconnectivity comparable to the human brain. This article is protected by copyright. All rights reserved.

Nitrogen-doped ZnO microspheres with a yolk-shell structure for high sensing response of triethylamine

Triethylamine is a kind of volatile organic compounds, which is harmful and toxic to the environment and people. Therefore, triethylamine gas sensors are increasingly demanded in practical applications. In this work, we synthesized the nitrogen-doped ZnO yolk-shell microspheres with mesoporous distribution by a facile strategy of hydrothermal-annealing. The influence of the amount of hexamethylene tetramine on the morphology of yolk-shell ZnO was studied and the yolk-shell ZnO (YSZ-3) prepared with 0.3 g hexamethylene tetramine showed the best gas sensing performances for triethylamine at 370 ℃. The response to 100 ppm triethylamine was 133. Moreover, a low triethylamine detection limit was achieved (1 ppm), with a response value of 2.6. The prepared yolk-shell ZnO showed an excellent selectivity to triethylamine, over ethanol, methanol, acetone, formaldehyde, ammonia, and toluene. Furthermore, YSZ-3 offered a low theoretical detection limit (42.4 ppb) and a fast response and recovery (20 s/5 s). Finally, the growth mechanism and gas sensing mechanism of yolk-shell ZnO were discussed.

Defect-Rich W/Mo-Doped V2O5 Microspheres as a Catalytic Host To Boost Sulfur Redox Kinetics for Lithium–Sulfur Batteries

It is very important to develop ideal electrocatalysts to accelerate the sulfur redox kinetics in both the discharging and charging processes for high-performance lithium-sulfur batteries. Herein, defect-rich cation-doped V2O5 yolk-shell microspheres are reported as a catalytic host of sulfur. The doping of W or Mo cations induces no impurities, broadens the lattice spacing of V2O5, and enriches the oxygen vacancy defects. Thus, the doped V2O5 host affords sufficient active sites for chemically anchoring polysulfides and promising catalytic effect on the mutual conversion between different sulfur intermediates. As a result, the S/W-V2O5 cathode delivers a discharging capacity of 1143.3 mA g-1 at an initial rate of 0.3 C and 681.8 mA g-1 at 5 C. Even under a sulfur loading of up to 5.5 mg cm-2 and a minimal electrolyte/sulfur ratio of 6 μL mg-1, the S/W-V2O5 cathode could still achieve good sulfur utilization and dependable cycle stability. Thus, this work offers an electrocatalytic host based on the cation doping strategy to greatly enhance the sulfur redox kinetics for high-performance Li-S batteries.

Morphology-controlled Co0.5Ni0.5S2-C double-shell porous microspheres for the construction of high-performance asymmetric supercapacitors

In this research, we develop a facile sulfuration treatment approach to synthesize the carbon doped double-shell porous cobalt nickel sulfide microspheres (Co0.5Ni0.5S2-C DSPMs) using CoNi-MOF yolk-shell microspheres (CoNi-MOF YSMs) as the precursor. The obtained Co0.5Ni0.5S2-C DSPMs exhibits a maximum specific capacity of 2011.3 F g − 1 at 1 A g − 1 due to the unique double-shell porous structure and amorphous carbon. The density functional theory (DFT) shows that cobalt nickel sulfide with the same molar ratio of cobalt and nickel possesses good absorbability and stability toward OH− ion on the thermodynamics, which significantly improves their electrochemical performance. Furthermore, an asymmetric supercapacitor (ASC) device is fabricated by using Co0.5Ni0.5S2C DSPMs as the cathode and the activated carbon (AC) as the anode. The ASC device exhibits a supreme specific capacity of 182.4 F g − 1 at 1 A g − 1, a high energy density of 64.85 Wh kg−1 at the power density of 800 W kg−1, and excellent cycle stability with 92.78% capacitance retention rate at the current density of 8 A g − 1 over 5000 cycles. This research pave the way for the development of next-generation energy storage devices using micro/nanocomposite with double-shell porous structure.

Construction of Cu7 S4 @CuCo2 O4 Yolk-Shell Microspheres Composite and Elucidation of Its Enhanced Photocatalytic Activity, Mechanism, and Pathway for Carbamazepine Degradation.

Water pollution caused by the massive use of medicines has caused significant environmental problems. This work first reports the synthesis and characterization of the Cu7 S4 /CuCo2 O4 (CS/CCO) yolk-shell microspheres via hydrothermal and annealing methods, and then investigates their photocatalytic performance in removing organic water pollutants. The 10-CS/CCO composite with yolk-shell microspheres exhibits the highest photodegradation rate of carbamazepine (CBZ), reaching 96.3% within 2h. The 10-CS/CCO also demonstrates more than two times higher photodegradation rates than the pure (Cu7 S4 ) CS and (CuCo2 O4 ) CCO. This outstanding photocatalytic performance can be attributed to the unique yolk-shell structure and the Z-scheme charge transfer pathway, reducing multiple reflections of the acting light. These factors enhance the light absorption efficiency and efficiently transfer photoexcited charge carriers. In-depth, photocatalytic degradation pathways of CBZ are systematically evaluated via the identification of degradation intermediates with Fukui index calculation. The insights gained from this work can serve as a guideline for developing low-cost and efficient Z-scheme photocatalyst composites with the yolk-shell structure.

Controllable Synthesis of Carbon Yolk-Shell Microsphere and Application of Metal Compound-Carbon Yolk-Shell as Effective Anode Material for Alkali-Ion Batteries.

Recently, nanostructured carbon materials, such as hollow-, yolk-, and core-shell-configuration, have attracted attention in various fields owing to their unique physical and chemical properties. Among them, yolk-shell structured carbon is considered as a noteworthy material for energy storage due to its fast electron transfer, structural robustness, and plentiful active reaction sites. However, the difficulty of the synthesis for controllable carbon yolk-shell has been raised as a limitation. In this study, novel synthesis strategy of nanostructured carbon yolk-shell microspheres that enable to control morphology and size of the yolk part is proposed for the first time. To apply in the appropriate field, cobalt compounds-carbon yolk-shell composites are applied as the anode of alkali-ion batteries and exhibit superior electrochemical performances to those of core-shell structures owing to their unique structural merits. Co3 O4 -C hollow yolk-shell as a lithium-ion battery anode exhibits a long cycling lifetime (619mA h g-1 for 400 cycles at 2 A g-1 ) and excellent rate capability (286mA h g-1 at 10 A g-1 ). The discharge capacities of CoSe2 -C hollow yolk-shell as sodium- and potassium-ion battery anodes at the 200th cycle are 311mA h g-1 at 0.5 A g-1 and 268mA h g-1 at 0.2 A g-1 , respectively.

Cation-doped V2O5 microsphere as a bidirectional catalyst to activate sulfur redox reactions for lithium-sulfur batteries

An ideal electrocatalyst for sulfur redox reactions (SRRs) should afford an exception catalysis upon the conversion between different sulfur compounds during both discharge and charge processes. Herein, we report transition-metal (M = Fe, Co, Ni) doped V2O5 yolk-shell microspheres (M-V2O5-YS) as a bidirectional catalytic host of sulfur. After doping, the M-V2O5-YS samples show abundant lattice defects and improved conductivity. Moreover, the doped metal ions enrich the active sites for the adsorption-catalysis of sulfur species. Kinetics tests results demonstrate the role of bidirectional catalyst for M-V2O5-YS hosts in speeding up the kinetics of the reduction of LiPSs, as well as the re-oxidation of the deposited Li2S. In particular, the S/Co-V2O5-YS composite shows an outstanding initial discharge capacity up to 1168.1 mAh/g at 0.3 C, rate capability (693.7 mAh/g at 5 C) and cycle stability. Even at low E/S ratio (6 μL mg−1) and high sulfur loading (4.9 mg cm−2), S/Co-V2O5-YS composite still harvest excellent capacity and satisfactory cycle stability. Therefore, this study displays an effective and feasible method to explore bidirectional catalytic materials to activate SRRs for high performance Li-S batteries.