Multi-shelled Hollow Structures Research Articles

Multi-shelled hollow porous carbon nanospheres-based evaporator for highly efficient solar-driven desalination

Carbon-based materials stand out as photothermal materials for interfacial solar evaporation due to their high solar absorptance, chemical stability, adjustable structure, ease of preparation, and low cost compared to other candidate materials. Development of multifunctional carbon-based materials that can endow the fabricated evaporators with reduced energy loss and evaporation enthalpy is highly demanded to achieve extraordinary evaporation rates. Herein, high-solar-absorptivity multi-shelled hollow porous carbon nanospheres are fabricated and incorporated with an insulating hydrogel bottom layer into an integrated solar evaporator. It achieves a fast photothermal response and a remarkably high solar evaporation rate of 2.4 kg m−2 h−1 under one sun. Multiphysics simulation indicates that the porous multi-shelled hollow structure enables sufficient and effective interactions between water and the hydrophilic carbon surfaces, thus producing more intermediate water (IW) and lowering the evaporation enthalpy. The solar-driven water evaporation in the evaporator is probed by in-situ low-field nuclear magnetic resonance relaxation time measurements, based on which conversion of free water (FW) into IW during solar evaporation is proposed. The molecular dynamics simulations reveal that the evolution of FW clusters into IW is facilitated on the carbon surface, thus replenishing the evaporated IW and maintaining continuous high evaporation rates. The demonstrated solar evaporator exemplifies the effectiveness of structural and thermal management in enhancing solar-driven desalination.

Balanced Polysulfide Containment and Lithium Ion Transport in Lithium-Sulfur Batteries via Nitrogen-doped Carbon Hollow Multi-shelled Structures on Modified Separators

Balanced Polysulfide Containment and Lithium Ion Transport in Lithium-Sulfur Batteries via Nitrogen-doped Carbon Hollow Multi-shelled Structures on Modified Separators

Synthesis of Mesoporous Silica Using the Sol-Gel Approach: Adjusting Architecture and Composition for Novel Applications.

The sol-gel chemistry of silica has long been used for manipulating the size, shape, and microstructure of mesoporous silica particles. This manipulation is performed in mild conditions through controlling the hydrolysis and condensation of silicon alkoxide. Compared to amorphous silica particles, the preparation of mesoporous silica, such as MCM-41, using the sol-gel approach offers several unique advantages in the fields of catalysis, medicament, and environment, due to its ordered mesoporous structure, high specific surface area, large pore volume, and easily functionalized surface. In this review, our primary focus is on the latest research related to the manipulation of mesoporous silica architectures using the sol-gel approach. We summarize various structures, including hollow, yolk-shell, multi-shelled hollow, Janus, nanotubular, and 2D membrane structures. Additionally, we survey sol-gel strategies involving the introduction of various functional elements onto the surface of mesoporous silica to enhance its performance. Furthermore, we outline the prospects and challenges associated with mesoporous silica featuring different structures and functions in promising applications, such as high-performance catalysis, biomedicine, wastewater treatment, and CO2 capture.

Rational Design of Coordination Polymers Composited Hollow Multishelled Structures for Drug Delivery.

Multifunctional drug delivery systems (DDS) are in high demand for effectively targeting specific cells, necessitating excellent biocompatibility, precise release mechanisms, and sustained release capabilities. The hollow multishelled structure (HoMS) presents a promising solution, integrating structural and compositional design for efficient DDS development amidst complex cellular environments. Herein, starting from a Fe-based metal-organic framework (MOF), amorphous coordination polymers (CP) composited HoMS with controlled shell numbers are fabricated by balancing the rate of MOF decomposition and shell formation. Fe-CP HoMS loaded with DOX is utilized for synergistic chemotherapy and chemodynamic therapy, offering excellent responsive drug release capability (excellent pH-triggered drug release 82% within 72h at pH 5.0 solution with doxorubicin (DOX) loading capacity of 284mg g-1). In addition to its potent chemotherapy attributes, Fe-CP-HoMS possesses chemodynamic therapy potential by continuously catalyzing H2O2 to generate ·OH species within cancer cells, thus effectively inhibiting cancer cell proliferation. DOX@3S-Fe-CP-HoMS, at a concentration of 12.5µg mL-1, demonstrates significant inhibitory effects on cancer cells while maintaining minimal cytotoxicity toward normal cells. It is envisioned that CP-HoMS could serve as an effective and biocompatible platform for the advancement of intelligent drug delivery systems in the realm of cancer therapy.

Mass Transfer Modulation by Hollow Multi‐Shelled Structures for High Space‐Time Yield Synthesis of Light Olefins from Syngas

AbstractThe separation of CO activation and C─C coupling enables oxide–zeolite catalyzed tandem reaction toward direct conversion of syngas into light olefins to be a promising alternative for the traditional Fischer–Tropsch process with elevated selectivity. Utilizing controlled mass transfer to match the activation of reactants and the coupling of intermediates presents an appealing strategy to break the limitation on space‐time yield in this tandem process. In this work, ZnCrOx hollow multi‐shelled structures (HoMS) are fabricated to enhance the adsorption and enrichment ability of syngas, thereby strengthening the rate‐determining activation step of reactants and resulting in an accelerated generation of intermediates. When coupled with SAPO zeolite, quintuple‐shelled ZnCrOx HoMS‐based catalysts exhibit a record high C2 = ‐C4 = space‐time yield of 559 mg·gcat−1·h−1 with a selectivity of 90%. This work demonstrates the advantages of precise nanostructure sculpturing on the mass transfer behavior in the microenvironment and provides a new strategy for highly selective direct conversion of syngas to light olefins, based on efficient activation of reactants and sufficient feeding of intermediates through enrichment effects within HoMS.

Intergrating Hollow Multishelled Structure and High Entropy Engineering toward Enhanced Mechano-Electrochemical Properties in Lithium Battery.

Hollow multishelled structures (HoMSs) are attracting great interest in lithium-ion batteries as the conversion anodes, owing to their superior buffering effect and mechanical stability. Given the synthetic challenges, especially elemental diffusion barrier in the multimetal combinations, this complex structure design has been realized in low- and medium-entropy compounds so far. It means that poor reaction reversibility and low intrinsic conductivity remain largely unresolved. Here, a hollow multishelled (LiFeZnNiCoMn)3O4 high entropy oxide (HEO) is developed through integrating molecule and microstructure engineering. As expected, the HoMS design exhibits significant targeting functionality, yielding satisfactory structure and cycling stability. Meanwhile, the abundant oxygen defects and optimized electronic structure of HEO accelerate the lithiation kinetics, while the retention of the parent lattice matrix enables reversible lithium storage, which is validated by rigorous in situ tests and theoretical simulations. Benefiting from these combined properties, such hollow multishelled HEO anode can deliver a specific capacity of 967 mAh g-1 (89% capacity retention) after 500 cycles at 0.5 A g-1. The synergistic lattice and volume stability showcased in this work holds great promise in guiding the material innovations for the next-generation energy storage devices.

A halide perovskite based ternary heterojunction with multi-shell hollow structure for stable and efficient artificial photosynthesis

Low-cost halide perovskite materials hold great promise as photocatalysts for CO2 reduction. However, their inferior water-tolerance will lead to a substantial decline in activity during prolonged photocatalytic CO2 reduction with water as the electron source. Herein, we integrate a lead-free halide perovskite Cs3Bi2I9 as photoactive layer with TiO2 as water oxidation catalyst and g-C3N4 as CO2 reduction catalyst to construct a ternary heterojunction (TiO2/Cs3Bi2I9/g-C3N4) with a multi-shell hollow structure. The formation of heterojunction endows TiO2/Cs3Bi2I9/g-C3N4 composite with enhanced photocatalytic activity for CO2 reduction due to the improved photogenerated carrier separation. TiO2/Cs3Bi2I9/g-C3N4 achieves a CO yield of 120.6 μmol g−1 h−1 for photocatalytic CO2 reduction, which is 3.1 times higher than that of individual Cs3Bi2I9. More importantly, benefitting from the double-sided protection of g-C3N4 and TiO2, the photocatalytic CO2 reduction activity of TiO2/Cs3Bi2I9/g-C3N4 remains undiminished even over 100 h of continuous light irradiation, demonstrating significantly improved stability in water-contained reaction system.

Trapping of heavy metal ions from electroplating wastewater with phosphorylated double-shelled hollow spheres

The mesoporous multi-shelled hollow structures are promising for trapping of non-degradable heavy metal ions in wastewater but difficult to synthesize. We successfully demonstrated a simple strategy for the construction of mesopore windows on double-shelled α-Fe2O3 hollow spheres. A step-by-step proof of concept synthesis mechanism has been revealed by using mainly electron microscopy and thermogravimetric analysis. We proved that mesopore windows are indispensable to realize the complete surface coverage of phosphonate ligands on α-Fe2O3 double-shelled hollow spheres. The phosphonic groups inherently coordinated with Ni(II) and Cu(II) ions and formed complexes of high stability. Importantly, owing to the structural merits, the phosphorylated double-shelled hollow spheres selectively removes Ni(II) and Cu(II) at wider sample pH range with a high capacity of 380 mg g−1 and 410 mg g−1, respectively. In addition, no significant decrease in the removal efficiency was observed under high salt matrix. For electroplating industry wastewater, the novel structure performs simultaneous Ni(II) and Cu(II) removal, thus producing effluent of stable quality that meets local discharge regulations.

Mesoscience in Hollow Multi-Shelled Structures.

The prevalence of mesoscale complexity in materials science underscores the significance of the compromise in competition principle, which gives rise to the emergence of mesoscience. This principle offers valuable insights into understanding the formation process, characteristics, and performance of complex material systems, ultimately guiding the future design of such intricate materials. Hollow multi-shelled structures (HoMS) represent a groundbreaking multifunctional structural system that encompasses several spatial regimes. A plethora of mesoscale cases within HoMS present remarkable opportunities for exploring, understanding, and utilizing mesoscience, varying from the formation process of HoMS, to the mesoscale structural parameters, and finally the distinctive mass/energy transfer behaviors exhibited by HoMS. The compromise in competition between the diffusion and reaction contributes to the successful formation of multi-shells of HoMS, allowing for precise regulation of the structural parameters by dynamically varying the interplay between two dominances. Moreover, the distinct roles played by the shells and cavities within HoMS significantly influence the energy/mass transfer processes with the unique temporal-spatial resolution, providing guidance for customizing the application performance. Hopefully, the empirical and theoretical anatomy of HoMS following mesoscience would fuel new discoveries within this promising and complex multifunctional material system.

Tunable synthesis of bimetallic hybrid multishelled hollow structure for high-performance aqueous alkaline batteries

Multishelled hollow structure (HoMS) with various metal components show alluring prospect due to the combined effects of various elements. But due to the different condensation and hydrolysis rates of different metal oxide precursors it is still a big challenge to synthesize multicomponent HoMSS. Here we report two different strategies: 1.Two-step strategy (TsS) and 2. One-step strategy (OsS) for the tunable synthesis of HoMSS with two transition metal oxide precursors (zinc chloride and titanium chloride) by using carbon microspheres as a hard template. As a result a number of crystalline mesoporous HoMSs of ZnO@TiO2 with varied thicknesses, high porosity, large specific surface area and different voids are synthesized. Synthesis strategies and conditions not only affect the shell numbers, thickness of the shell, pore size, surface area and size of the voids but also the amount of absorbed metal ions (Zn2+ and Ti4+) varied. We compared their performances as cathode in aqueous alkaline battery and found that the ZnO@TiO2 HoMSS synthesized by OsS (triple shelled) exhibit excellent high potassium storage capacity, good rate capability, outstanding reversibility, and steady long cyclic life. The thinner shell, larger pore size, high surface area, and bigger voids contribute a distinctive buffering zone for charge-discharge, thus improving the structural stability and enhance the cycling stability during OH intercalation/de-intercalation process. ZnO@TiO2 triple shelled HoMSS with large pore size and big voids delivers a high discharge specific capacity of 260 mAhg−1 at a current density of 1 Ag−1, and capacity enhanced to 270 mAhg-1 over 1000 cycles.

The role of concentration waves in synthesizing hollow multi-shelled structures

Recently in Angewandte Chemie International Edition, Wang and co-workers presented a comprehensive study that combines a mathematical model with experiments to reveal the key role of concentration waves in the formation of hollow multi-shelled structures (HoMSs) and provides a theoretical guideline for the precise engineering of HoMSs for targeted applications. Recently in Angewandte Chemie International Edition, Wang and co-workers presented a comprehensive study that combines a mathematical model with experiments to reveal the key role of concentration waves in the formation of hollow multi-shelled structures (HoMSs) and provides a theoretical guideline for the precise engineering of HoMSs for targeted applications.

Innenrücktitelbild: A Universal Formation Mechanism of Hollow Multi‐Shelled Structures Dominated by Concentration Waves (Angew. Chem. 28/2023)

The concentration wave dominated universal formation mechanism of hollow multi-shelled structures (HoMS) is revealed by numerical simulation, as reported by Wei Ge, Dan Wang and co-workers in their Research Article (e202302621). The discovery of the physical essence behind the formation of HoMS not only flourishes the environment for HoMS synthesis, but also offers a predictive blueprint for creating dynamic HoMS by concentration waves, thereby establishing a valuable framework for future research in the realm of synthetic chemistry.

Inside Back Cover: A Universal Formation Mechanism of Hollow Multi‐Shelled Structures Dominated by Concentration Waves (Angew. Chem. Int. Ed. 28/2023)

The concentration wave dominated universal formation mechanism of hollow multi-shelled structures (HoMS) is revealed by numerical simulation, as reported by Wei Ge, Dan Wang and co-workers in their Research Article (e202302621). The discovery of the physical essence behind the formation of HoMS not only flourishes the environment for HoMS synthesis, but also offers a predictive blueprint for creating dynamic HoMS by concentration waves, thereby establishing a valuable framework for future research in the realm of synthetic chemistry.

A Universal Formation Mechanism of Hollow Multi-Shelled Structures Dominated by Concentration Waves.

Hollow multi-shelled structures (HoMS), a new family of hierarchical nano/micro-structured materials, have evoked intensive studies to discover their unique temporal-spatial ordering features. The theoretical understanding of the general synthetic methods of HoMS, i. e. the sequential templating approach (STA), makes it possible to understand, predict, and control the shell formation process. Herein, a mathematical model is established based on the experiment results, which reveal the appearance of concentration waves in the STA. The numerical simulation results not only correspond well to the experimental observations but also explain the regulation methods. Whereby, the underlying physical essence of STA is elucidated, suggesting that HoMS is the concrete representation of the concentration waves. Thereafter the formation of HoMS is not limited to the solid-state reactions through high-temperature calcination, but could be extended to synthetic systems under mild conditions.

Combing Hollow Shell Structure and Z-Scheme Heterojunction Construction for Promoting CO2 Photoreduction

CO2 photoreduction is considered one of the potential ways to achieve carbon neutralization since it uses green solar energy without introducing additional carbon sources during the process of converting CO2 to fuels. However, limited light utilization and poor charge separation often give rise to undesirable CO2 photoreduction performance. Herein, a generic approach using carbon spheres as templates to construct transition metal oxides with multishelled hollow structures is reported. The multishelled hollow structure has been proven to be efficient for improving CO2 photoreduction. Furthermore, we constructed a Z-scheme heterojunction photocatalyst (CdS/Au/ZnCrO4) through introducing CdS into a multishelled hollow ZnCrO4 sphere with Au nanoparticles as a charge transfer medium. Benefiting from the multishelled hollow structure’s induced light utilization and large surface area and Z-scheme heterojuncion promoted charge separation, a high CO production of 2.95 μmol g–1 h–1 was achieved on CdS/Au/ZnCrO4 without using any sacrificial agents, which was 18.4 times and 24.6 times higher than that of CdS and ZnCrO4. This work provides a generic method for constructing controllable multishelled hollow spheres and is expected to offer guidance for promoting CO2 photoreduction through structure regulation and heterojunction construction.

Response and Regulation of the Microenvironment Based on Hollow Structured Drug Delivery Systems

AbstractHollow structured materials with easily modifiable surfaces and enclosed interior spaces have emerged as the most promising candidates in drug delivery systems (DDS). With various functional components and inspiring cavities for creative reinvention, the response and regulation of the external and internal microenvironment of hollow structures enable their ideal drug delivery capabilities by improving drug aggregation in targeted sites and maintaining plasma concentrations at the optimal therapeutic ranges. This review begins with an in‐depth explanation of the interactions and release mechanisms of hollow structure‐based DDS, including diffusion, assembly, solvent activation, and chemical control, all of which are of great significance for the design of smart drug carriers. Next, recent advances in external microenvironment‐responsive drug delivery systems are introduced, based on various chemical signals and external field assists. Focusing on the unique view of intra‐carrier variability, the strategies for regulating the internal environment are then highlighted, including pH regulation, temperature regulation, and mechanical force regulation. Finally, this review discusses possible challenges and prospects for hollow structure‐based, particularly hollow multishelled structures intelligence‐responsive drug delivery platforms, providing valuable strategies for the development of the next generation of responsive DDS.

The construction of defect-rich CoP@CoP@(Co/Ni)2P triple-shell hollow nanospheres with boosted electrocatalytic hydrogen evolution performances over a wide pH range

The development of highly effective non-precious metal catalysts with high intrinsic activity and rich accessible catalysis centers are the relentless goals of the scientific community to lower energy consumption and production cost. In this work, a unique triple-shell CoP@CoP@(Co/Ni)2P hollow structure with rich defect structure has been successfully constructed, which presents remarkable activity against HER over a wide pH range. The overpotentials of 147 mV, 139 mV, and 144 mV are achieved at 10 mA cm−2 current density for CoP@CoP@(Co/Ni)2P in 1 M KOH, 0.5 M H2SO4, and 1 M phosphate-buffered saline (PBS) conditions, respectively. The excellent HER activity of CoP@CoP@(Co/Ni)2P can be attributed to their multi-shell hollow structure for abundant activity centers, and rich defect structure for the enhanced intrinsic activity. This work provides new insights into the design and synthesis of multi-shell hollow structures with diverse compositions and defect-rich catalysts for energy storage and conversion application.

Hollow Nanomaterials in Advanced Drug Delivery Systems: From Single- to Multiple Shells.

Hollow-structured nanomaterials (HSNMs) have attracted increased interest in biomedical fields, owing to their excellent potential as drug delivery systems (DDSs) for clinical applications. Among HSNMs, hollow multi-shelled structures (HoMSs) exhibit properties such as high loading capacity, sequential drug release, and multi-functionalized modification and represent a new class of nanoplatforms for clinical applications. The remarkable properties of HoMS-based DDS can simultaneously satisfy and enhance DDSs for delivering small molecular drugs (e.g., antibiotics, chemotherapy drugs, and imaging agents) and macromolecular drugs (e.g., protein/peptide- and nucleic acid-based drugs). First, the latest research advances in delivering small molecular drugs are summarized and highlight the inherent advantages of HoMS-based DDSs for small molecular drug targeting, combining continuous therapeutic drug delivery and theranostics to optimize the clinical benefit. Meanwhile, the macromolecular drugs DDSs are in the initial development stage and currently offer limited delivery modes. There is a growing need to analyze the deficiency of other HSNMs and integrate the advantages of HSNMs, providing solutions for the safe, stable, and cascade delivery of macromolecular drugs to meet vast treatment requirements. Therefore, the latest advances in HoMS-based DDSs are comprehensively reviewed, mainly focusing on the characteristics, research progress by drug category, and future research prospects.

Controllable construction of multi-shelled ZnSnO3 hollow microspheres as high-performance sensing material for acetone detection

Multi-shelled hollow structures have been drawing wide attention in various fields because of their large surface area, short diffusion path and less agglomerated configuration. Herein, ZnSnO3 hollow microspheres with controllable shell numbers have been prepared by a facile solvothermal reaction and following annealing treatment. The test results show that multi-shelled ZnSnO3 hollow microspheres exhibit excellent acetone sensing performance, which is superior than that of double-shelled samples. In particular, multi-shelled ZnSnO3 hollow microspheres not only show high responses of 105.1 and rapid response/recovery speed (1/18 s) to 100 ppm acetone, but also exhibit good repeatability, long-term stability and anti-humidity properties. Furthermore, they can easily distinguish healthy breath from simulated diabetic breath. And they still show rapid response/recovery speed in actual breath detection, which is beneficial to the achievement of real-time detection. The enhanced sensing performance has been studied systematically. Thus, multi-shelled ZnSnO3 hollow microspheres have a great potential for the diagnosis of diabetes.

PEG-Functionalized Hollow Multishelled Structures with On-Off Switch and Rate-Regulation for Controllable Antimicrobial Release.

The construction of responsive antimicrobial carriers with multifunctional and controllable release is an attractive but challenging proposition. Recently developed hollow multishelled structures (HoMSs) offers structural advantages, such as easily modifiable surfaces and mutually influenced shells. Herein, we report a novel pH-responsive antimicrobial carrier having hierarchical shells as multilevel responsive bodies using polyethylene glycol (PEG) as a gated regulator. The interaction between PEG-functionalized shells endows them with a pH-responsive switch and rate-regulator capability. These features are present in the form of rapid release of molecules wrapped in the outer shell, and controlled diffusion of antimicrobials stored in the inner shell by electrostatic interaction, resulting in a long-lasting mildew resistance for up to 71 days. The versatility of the hierarchical interactions of HoMSs will inspire the design of promising smart drug carriers.