Multi-shelled Hollow Structures Research Articles

Nanometer Puzzle Ball, Controlled Drug Release Just Got More Options

Biological cells express isolated cavities and hierarchical pores with various physiological roles. In a recent work by Dan Wang and colleagues, synthetic hollow multi-shelled structures (HoMSs) are designed to mimic cells and act as a delivery system for antibacterial agents with three distinct sequential release stages—burst release, sustained release, and stimulus-responsive release—in one system.

Hollow hierarchically porous La2O3 with controllable multishells: A high-performance adsorbent for phosphate removal

Multi-shelled nanomaterials, especially with hierarchically porous structures, are very promising for a variety of potential applications. Herein, the multi-shelled hollow La2O3 nanospheres (MHLN) with high specific surface areas and numerous active sites are first fabricated via a facile and universal synthetic strategy characterized by step-by-step thermal removal of templates. The shell numbers can be easily controlled by adjusting the precursor amount adsorbed into the template. The formation mechanism of the MHLN reveals that the hierarchical assembly of the La2O3 nanoparticles generates the smaller mesoporous of the shells, which providing a complicated but ordered three dimensional network for the MHLN. Notably, the combination of the multi-shelled hollow structure and the special hierarchical pores endows La2O3 nanospheres not only with a large specific surface area but also with good porosity and permeability. Further functional investigation shows that MHLN exhibit a higher removal capacity (192.68 mg P g−1) for phosphate than the reported previously, a fast sorption and exhibit a good stability in wide pH range and excellent reusability.

Photocatalysts: Steering Hollow Multishelled Structures in Photocatalysis: Optimizing Surface and Mass Transport (Adv. Mater. 44/2020)

Photocatalysts: Steering Hollow Multishelled Structures in Photocatalysis: Optimizing Surface and Mass Transport (Adv. Mater. 44/2020)

Multiphase Drug Release in Hollow Multishelled Structures

Recently in Nature Communications, Profs. Dan Wang, Suojiang Zhang, and colleagues report a highly versatile drug-delivery platform showing a promising step toward a sequential-release capability. In careful detail, they report drug-release profiles, mass-transport phenomena, and applications for enhanced bacterial sterilization.

Small Structures Bring Big Things: Performance Control of Hollow Multishelled Structures

Hollow multishelled structures (HoMSs) have gained numerous achievements in broad scientific research fields. In the past decade, the rapid developments of synthetic methods and advanced characterization technologies have enriched HoMS family with abundant chemical compositions and geometric structures. In addition, the control in phase structure and surface structure of HoMSs have also been reported in recent years. With great efforts devoted to controlling the compositional and structural characteristics, such as shell composition, shell number, shell thickness, and intershell space, HoMSs have displayed their intrinsic temporal–spatial nature and proven to be fruitful in optimizing mass transport, storage, and release. This review first summarizes the compositional and structural control of HoMSs in three levels, that is, building subunits, assembled functional shells, and HoMSs. Subsequentially, the essential influence of composition and structure on mass transport, storage, and release is deeply discussed by highlighting the application of HoMSs in energy storage, catalysis, electromagnetic wave absorption, and drug delivery. Finally, the challenges and opportunities in the future development of HoMSs are forecasted.

Accurate Control of All-Polymer Hollow Multishelled Spheres by One-Step Reaction–Diffusion

Hollow multishelled structures (HoMSs) enable material intriguing properties and diverse applications. However, constructing all-polymer HoMSs (p-HoMSs) remains a great challenge. Here, we first de...

Sequential drug release via chemical diffusion and physical barriers enabled by hollow multishelled structures

Hollow multishelled structures (HoMSs), with relatively isolated cavities and hierarchal pores in the shells, are structurally similar to cells. Functionally inspired by the different transmission forms in living cells, we studied the mass transport process in HoMSs in detail. In the present work, after introducing the antibacterial agent methylisothiazolinone (MIT) as model molecules into HoMSs, we discover three sequential release stages, i.e., burst release, sustained release and stimulus-responsive release, in one system. The triple-shelled structure can provide a long sterility period in a bacteria-rich environment that is nearly 8 times longer than that of the pure antimicrobial agent under the same conditions. More importantly, the HoMS system provides a smart responsive release mechanism that can be triggered by environmental changes. All these advantages could be attributed to chemical diffusion- and physical barrier-driven temporally-spatially ordered drug release, providing a route for the design of intelligent nanomaterials.

Dual‐Defects Adjusted Crystal‐Field Splitting of LaCo1−xNixO3−δ Hollow Multishelled Structures for Efficient Oxygen Evolution

AbstractTo boost the performance for various applications, a rational bottom‐up design on materials is necessary. The defect engineering on nanoparticle at the atomic level can efficiently tune the electronic behavior, which offers great opportunities in enhancing the catalytic performance. In this paper, we optimized the surface oxygen vacancy concentration and created the lattice distortion in rare‐earth‐based perovskite oxide through gradient replacement of the B site with valence alternated element. The dual defects make the electron spin state transit from low spin state to high spin state, thus decreasing the charge transport resistance. Furthermore, assembly the modified nanoparticle subunits into the micro‐sized hollow multishelled structures can provide porous shells, abundant interior space and effective contact, which enables an enhanced mass transfer and a shorter charge transport path. As a result, the systemic design in the electronic and nano‐micro structures for catalyst has brought an excellent oxygen evolution performance.

Dual-Defects Adjusted Crystal-Field Splitting of LaCo1-x Nix O3-δ Hollow Multishelled Structures for Efficient Oxygen Evolution.

To boost the performance for various applications, a rational bottom-up design on materials is necessary. The defect engineering on nanoparticle at the atomic level can efficiently tune the electronic behavior, which offers great opportunities in enhancing the catalytic performance. In this paper, we optimized the surface oxygen vacancy concentration and created the lattice distortion in rare-earth-based perovskite oxide through gradient replacement of the B site with valence alternated element. The dual defects make the electron spin state transit from low spin state to high spin state, thus decreasing the charge transport resistance. Furthermore, assembly the modified nanoparticle subunits into the micro-sized hollow multishelled structures can provide porous shells, abundant interior space and effective contact, which enables an enhanced mass transfer and a shorter charge transport path. As a result, the systemic design in the electronic and nano-micro structures for catalyst has brought an excellent oxygen evolution performance.

Steering Hollow Multishelled Structures in Photocatalysis: Optimizing Surface and Mass Transport.

Hollow multishelled structures (HoMSs) provide a promising platform for fabricating photocatalysts, because the unique structure optimizes the effective surface and mass transport, showing enhanced light absorption, optimized mass transport and highly effective active sites exposed. Subsequently, the rational design on HoMS photocatalytsts is elaborated to boost the photocatalytic activity with efforts in all dimensions, from nanoscale to microscale. Breakthroughs in synthetic methodology of HoMSs have greatly evoked the prosperous photocatalytic researches for HoMSs since the developing of sequential templating approach in 2009. The dawn of HoMS photocatalyst is coming after revealing the temporal-spatial ordering property, which is also discussed in this paper with pioneer works demonstrating the greatly enhanced energy/mass transfer processes. Some insights into the key challenges and perspectives of HoMSs photocatalysts are also discussed. With the reviewed fate and future of HoMSs photocatalysts, hopefully new concepts and innovative works can be inspired to flourish this sun-rise field.

Nature and Chinese Art Inspire Materials for Light Harvesting

The Holy Grail of materials science and engineering is to understand and control structure-property relationships in materials systems, so as to attain the long-standing goal of materials by design. In this Preview, we describe recently synthesized hollow multi-shelled structures (HoMSs), a porous nanomaterial whose complex architecture was inspired both by nature and by the puzzle ball—an ancient Chinese artifact. Thanks to the precise control of structure and composition, HoMSs allow to sequentially harvest sunlight, leading to improved photocatalytic activity for hydrogen production from water.

Promising hollow multi-shelled structures: discovering the temporal-spatial ordering.

Promising hollow multi-shelled structures: discovering the temporal-spatial ordering.

Development of Magnetic Multi-Shelled Hollow Catalyst for Biodiesel Production

The magnetic CaO-based catalyst has endorsed great enhancements in biodiesel synthesis. In the present work, novel multi-shelled hollow γ-Fe2O3 stabilized CaO microspheres were synthesized using a facile one-step hydrothermal method. The strategy revealed that the well-defined multi-shelled hollow structures were formed with magnetism; the presence of γ-Fe2O3 was the key for the effective structural stabilization, and the multi-shelled hollow structures provided the sites for the active material. The synthesized catalyst was employed for the preparation of biodiesel by transesterification of palm oil and methanol. A four factors response surface methodology was adopted for optimizing the reaction conditions. Ca80Fe20 with a yield of 96.12% performed the highest catalytic activity under reaction conditions of 2 h, a methanol to oil ratio of 12:1, 65 °C and 11 wt. % of catalyst dosage. The catalyst under the optimum transesterification conditions also performed a better recyclability (>85%). In addition, the response surface methodology (RSM) based on the Box–Behnken design was used to optimize the four reaction parameters.

Dan Wang.

"My biggest inspiration is the Chinese puzzle ball. This traditional artwork possesses characteristics desired for scientific study and practical application of materials, and it inspired our hollow multi-shelled structures …" Find out more about Dan Wang in his Author Profile.

Efficient sequential harvesting of solar light by heterogeneous hollow shells with hierarchical pores.

In nature, sequential harvesting of light widely exists in the old life entity, i.e. cyanobacteria, to maximize the light absorption and enhance the photosynthesis efficiency. Inspired by nature, we propose a brand new concept of temporally-spatially sequential harvesting of light in one single particle, which has purpose-designed heterogeneous hollow multi-shelled structures (HoMSs) with porous shells composed of nanoparticle subunits. Structurally, HoMSs consist of different band-gap materials outside-in, thus realizing the efficient harvesting of light with different wavelengths. Moreover, introducing oxygen vacancies into each nanoparticle subunit can also enhance the light absorption. With the benefit of sequential harvesting of light in HoMSs, the quantum efficiency at wavelength of 400 nm is enhanced by six times compared with the corresponding nanoparticles. Impressively, using these aforementioned materials as photocatalysts, highly efficient photocatalytic water splitting is realized, which cannot be achieved by using the nanoparticle counterparts. This new concept of temporally-spatially sequential harvesting of solar light paves the way for solving the ever-growing energy demand.

Template-free Synthesis of Mesoporous and Crystalline Transition Metal Oxide Nanoplates with Abundant Surface Defects

Summary Mesoporous transition metal oxides with crystalline walls show promising applications in catalysis and energy storage. Syntheses of those crystalline mesoporous oxides, however, currently remain as an unmet challenge because of the large volume shrinkage during crystallization in a sol-gel process. Here, we demonstrate a facile and general template-free method to prepare six mesoporous transition metal oxides, e.g., CuO, CoO, and spinel MCo2O4 (M = Co, Cu, Mn, Zn), with highly crystalline walls and continuous mesopores in the forms of two-dimensional nanoplates or nanosheets. The method is based on the thermal crystalline transformation from basic carbonates to mesoporous metal oxides. The crystal interconversion not only endows the crystallinity and mesoporosity of oxides but also generates abundant surface-step defects that show remarkable enhancement of the catalytic activity of porous oxides. Our method likely provides an alternative paradigm for cost-effective and universal synthesis of crystalline mesoporous oxides beyond the traditional templating methods.

Defect-Rich Multishelled Fe-Doped Co3O4 Hollow Microspheres with Multiple Spatial Confinements to Facilitate Catalytic Conversion of Polysulfides for High-Performance Li-S Batteries.

Over the past decade, lithium-sulfur (Li-S) batteries have been thought of as promising alternatives for the new generation of battery systems. Although the Li-S batteries possess high-theoretical energy density (2600 Wh kg-1) and capacity (1675 mAh g-1), the problems of poor electron and ion conduction, volumetric expansion, and sulfur immobilization greatly impede the wide applicability of Li-S batteries. Herein, a defect-rich multishelled Co3O4 microsphere structure doped with Fe was synthesized via a one-step hydrothermal method and subsequent thermal treatment. The unique multishelled structure provides multiple spatial confinements for lithium polysulfides trapping and buffering the volume variation during cycling. Moreover, the rich oxygen defect designed by controlled Fe doping can provide numerous catalytic sites for polysulfide redox reactions. Attributed to the synergistic effect of structural design and oxygen-defect fabrication, the sulfur composite electrode delivers a notable cycle performance, presenting a much lower capacity fading of 0.017% per cycle over 1000 cycles at 1 C and an excellent rate capability of 571.3 mAh g-1 at 5 C. This work proposes a potential approach for designing a transition metal oxide-based multishelled hollow structure combined with oxygen defect, which also offers a new perspective on high-performance Li-S batteries.

A Hollow Multi‐Shelled Structure for Charge Transport and Active Sites in Lithium‐Ion Capacitors

AbstractThe lithium‐ion capacitor (LIC) has attracted tremendous research interest because it meets both the requirement on high energy and power densities. The balance between effective surface areas and mass transport is highly desired to fabricate the optimized electrode material for LIC. Now, triple‐shelled (3S) Nb2O5 hollow multi‐shelled structures (HoMSs) were synthesized for the first time through the sequential templating approach and then applied for the anode of LIC. The unique structure of HoMSs, such as large efficient surface area, hierarchical pores, and multiple shells, provides abundant reaction sites, decreases the electron transport resistance, and increases the diffusion rate for ion transport. In this case, the best combination performance has been achieved among all the reported Nb2O5‐based materials, which delivered an excellent energy and power densities simultaneously, and superb cycling stability.

A Hollow Multi-Shelled Structure for Charge Transport and Active Sites in Lithium-Ion Capacitors.

The lithium-ion capacitor (LIC) has attracted tremendous research interest because it meets both the requirement on high energy and power densities. The balance between effective surface areas and mass transport is highly desired to fabricate the optimized electrode material for LIC. Now, triple-shelled (3S) Nb2 O5 hollow multi-shelled structures (HoMSs) were synthesized for the first time through the sequential templating approach and then applied for the anode of LIC. The unique structure of HoMSs, such as large efficient surface area, hierarchical pores, and multiple shells, provides abundant reaction sites, decreases the electron transport resistance, and increases the diffusion rate for ion transport. In this case, the best combination performance has been achieved among all the reported Nb2 O5 -based materials, which delivered an excellent energy and power densities simultaneously, and superb cycling stability.

V2 O5 Textile Cathodes with High Capacity and Stability for Flexible Lithium-Ion Batteries.

Textile-based energy-storage devices are highly appealing for flexible and wearable electronics. Here, a 3D textile cathode with high loading, which couples hollow multishelled structures (HoMSs) with conductive metallic fabric, is reported for high-performance flexible lithium-ion batteries. V2 O5 HoMSs prepared by sequential templating approach are used as active materials and conductive metallic fabrics are applied as current collectors and flexible substrates. Taking advantage of the desirable structure of V2 O5 HoMSs that effectively buffers the volume expansion and alleviates the stress/strain during repeated Li-insertion/extraction processes, as well as the robust flexible metallic-fabric current collector, the as-prepared fabric devices show excellent electrochemical performance and ultrahigh stability. The capacity retains a high value of 222.4 mA h g-1 at a high mass loading of 2.5 mg cm-2 even after 500 charge/discharge cycles, and no obvious performance degradation is observed after hundreds of cycles of bending and folding. These results indicate that V2 O5 HoMSs/metallic-fabric cathode electrode is promising for highly flexible lithium-ion batteries.