Hierarchical Shell Structure Research Articles

Cell membrane-inspired regulation of reactant diffusion for active agent microencapsulation via interface engineering

Microencapsulation of hydrophilic amines in nonaqueous emulsions provides opportunities for a variety of applications, such as CO2 absorbents, and adhesives, but also presents challenges due to the intense reactant diffusion and disruptive interfacial reaction kinetics. Drawing inspiration from cellular systems, where cell membranes effectively regulate mass transfer for essential activities, we propose an interface engineering approach to manage interfacial reactant diffusion. This strategy obviates the modification of emulsion phases with additives in literature, which lowered effective core content. To achieve this, a solvent-induced polymer self-assembling method is adopted. The self-assembled polymer effectively formed a stabilizing viscoelastic film, which kinetically traps the microdroplets, serves as a viscous barrier lowering intense amine diffusion and interfacial polymerization kinetics, and provides protection for the microdroplets against the destructive forces from reaction turbulence and emulsion collision. This approach possesses high tolerance against microencapsulation conditions and is technically friendly, laying the groundwork for scalable microencapsulation of amines to meet industrial demands. We successfully synthesized Tetraethylenepentamine (TEPA)-loaded microcapsules with adjustable shell tightness, hierarchical shell structures, high shell strength and high core content. The method's versatility is further evidenced with different species containing reactive hydrogens. The demonstrated potential of TEPA-loaded microcapsules in effective CO2 capture and instant adhesives provides a fresh perspective on the microencapsulation of distinct polar payloads through interface engineering and its wide-ranging applications.

ZnSn(OH)6 nanocube/ Zn2SnO4 nanowires yolk–shell hierarchical structure with tunable band gap for deep-UV photodetection

Ternary oxides nanomaterials (TONs) are the mostly investigated as a promising candidate for ultraviolet detection due to its excellent photoconductivity. Among them, Zn2SnO4 (ZTO) has received extensive attention, but its advantages cannot be utilized in deep-ultraviolet (DUV) detection due to band gap limitation. Herein, we synthesized ZnSn(OH)6 nanocube/ ZTO nanowires yolk–shell hierarchical structure with tunable band gap between 3.6 and 4.4 eV by the dual laser ablation in liquid plus hydrothermal method. This hierarchical structure is applied to DUV photodetection and the results showed that it could improve the Ilight/ Idark ratio of ZTO DUV photodetection by two orders of magnitude while retaining the advantage of ZTO’s rapid response time (τrise =0.43 ms, τdecay =0.55 ms). Moreover, deep-UV imaging is also realized based on this material. This approach provides a new way of tuning the TONs’ band gap and its application to DUV photodetection or imaging.

Low-Temperature Cu-Cu Bonding by Using Cu₂O Nanoparticle Coated Hierarchical Structure

To solve the problems of high cost of Cu nanoparticles (NPs) and high bonding temperature of Cu microparticles (MPs), a Cu₂O NP-coated hierarchical structure (Cu-MP&#x0040;Cu₂O-NP) was proposed and fabricated for low-temperature Cu&#x2013;Cu bonding. The Cu-MP&#x0040;Cu-NP particles were obtained by Cu MPs through preoxidation and <i>in situ</i> reduction process, which formed a Cu particle with micro&#x2013;nano core&#x2013;shell hierarchical structure. The effect of preoxidation temperature on morphological features of Cu-MP&#x0040;Cu₂O-NP particles and mechanical properties of bonded joints were investigated. After reduction process, the generated Cu₂O NPs on the surface of the hierarchical structure were reduced to Cu NPs completely. The surface NPs significantly enhanced the sinterability and structure density. After sintering at 300 &#x00B0;C, the shear strength of the bonded joints improved to 23.7 MPa, which is higher than that of Cu MPs without hierarchical structure. A sintering mechanism of Cu-MP&#x0040;Cu-NP particles was proposed, revealing the surface NP layer is the key factor in this bonding process.

Low-Temperature Solution-Processed Synthesis of Hollow SnO2@TiO2 Core–Shell Hierarchical Structure for Self-Powered Ultraviolet Photodetectors

The interest in investigating hollow core–shell nanostructures was stimulated by their intrinsic advantage in light absorption and photocarrier separation for promising applications in photoelectrochemical devices. Here, SnO2@TiO2 core–shell hierarchical tubular structure was designed and prepared via a low-temperature solution route using carbon nanofibers as templates. The heterostructure consists of SnO2 nanotubes and TiO2 nanocones, which facilities photocarrier separation and transport by built-in electric field at their interface, and direct transport path served by SnO2 nanotubes. The large specific surface area was also believed to contribute to improve performance by providing more active sites for chemical reactions. After assembling into a photoelectrochemical-type ultraviolet photodetector, the detector exhibits a high short-circuit photocurrent density of 870 μA cm–2 under ultraviolet illumination (λ = 365 nm) of 35 mW cm–2 without bias voltage. The photosensitivity can reach up to 3781, and the feature response time was in microseconds, 33 ms for rise process and 13 ms for decay process. It is believed that this structure with combined advantageous features is extendable to other photoelectrochemical cases, such as dye-sensitized solar cells and artificial photosynthesis.

CuO dot-decorated Cu@Gd2O3 core-shell hierarchical structure for Cu(i) self-supplying chemodynamic therapy in combination with MRI-guided photothermal synergistic therapy.

Theoretically, the Fenton catalytic efficiency of the Cu-based nanoplatform is approximately 160 times that of traditional Fe-based agents. However, the coordination interaction between Cu(ii) and intracellular GSH significantly inhibits the high catalytic activity of Cu(i) generation, dramatically decreasing the Fenton-like catalytic efficiency. Herein, we designed a completely new and highly efficient hierarchical structural nanoplatform to enhance the mimic-peroxidase activity through utilizing comproportionation between CuO and elemental Cu core to self-supply Cu(i). The catalytic rate of this nanoplatform was approximately 55-fold that of traditional Fe-based agents. In a cell assay, this nanoplatform could function as an antagonist of GPX4 and agonist of SOD-1, resulting in intracellular ROS and H2O2 accumulation. Next, the accumulated H2O2 could be quickly catalyzed to highly toxic ˙OH by self-supplying Cu(i), causing strong oxidative stress damage to mitochondria and cell membranes. Under 808 nm laser irradiation, this nanoplatform exhibited a stronger inhibition of tumor growth, and effectively overcame the tumor resistance and recurrence. In addition, this hierarchical structure significantly promoted the interaction between water molecules and gadolinium centers, making TRF-mCuGd possess an ultrahigh T1 MRI contrast performance, and hence, more pathological information of the tumor could be achieved. Overall, this work provides a promising pattern for the design and development of cancer theranostics.

Synthesis and properties of multifunctional microencapsulated phase change material for intelligent textiles

Microencapsulated phase change materials (MEPCMs) have been widely used in many fields as thermal energy storage materials. This study reported a novel MEPCM with the functions of thermal energy storage, photothermal conversion, ultraviolet (UV) shielding, and superhydrophobicity, which was particularly suitable for intelligent textiles. The microcapsules based on an n-eicosane core and a CuO-doped polyurea shell with hierarchical structure were fabricated through a one-step interfacial polymerization. The morphology of the capsules and the hierarchical shell structure were identified through scanning and transmission electron microscopy. Thermal analysis indicated that the microcapsules had a high latent heat of 162.3 J/g and demonstrated a high thermal reliability. These microcapsules achieved a good photothermal conversion capability and can reduce UV radiation by approximately 30%. The water contact angle of the MEPCM was over 148° and showed a good superhydrophobic property. Cotton fabric coated with the prepared MEPCM was investigated. Results showed that it achieved a high phase change enthalpy of 36.8 J/g, an effective thermoregulation capability, and a large contact angle of 141.6°.

Polyaniline‐Modified Hierarchical Graphene Fiber for Ultrahigh‐Performance Electrochemical Supercapacitor with Carbon Fiber in Core as Current Collector

As the demand for portable and wearable energy‐storage devices increases, fiber‐type supercapacitors have rapidly developed. Herein, a two‐step synthesis method is developed to fabricate polyaniline‐modified hierarchical graphene fibers (GFs) with carbon fiber as the core. Using these fibers as the electrode of the supercapacitor, the highly conductive graphene sheets in these fibers can accelerate the transfer of electrolyte ions and fully enhance the Faraday redox transition of polyaniline on the fiber surface, thus realizing the volume capacitance of 2053 F cm−3. The core–shell hierarchical structures contribute to the high robustness and flexibility of the fibers, which are beneficial to their application in wearable or flexible systems. Moreover, large‐scale production of the core–shell fibers as supercapacitor electrodes without metal wires can be easily realized by a simple bonding technique, which opens up a promising opportunity for practical flexible devices.

Monodispersed Silica@Nickel Silicate Hydroxide Core–Shell Spheres for Supercapacitor Electrodes

Monodispersed silica@nickel silicate hydroxide core–shell microspheres are prepared using a hydrothermal method. The core–shell microsphere with an average diameter of 525 nm displays a hierarchical structure. The shell with an average thickness of about 40 nm consists of Ni3Si2O5(OH)4 nanosheets yielding porous surface. Surface‐dependent electrochemical property exhibits a specific capacitance of 356.7 F g−1 at 0.5 A g−1 and a good rate performance, which is attributed to the special core–shell hierarchical structures not only providing abundant electroactive sites for redox reaction but also shortening ion/electron transportation path. The current study provides a simple and efficient way to design low‐cost electrodes for supercapacitors.

Constructing ZnCo2O4@LDH Core–Shell hierarchical structure for high performance supercapacitor electrodes

Abstract In this article, ZnCo 2 O 4 nanowires deposited with two kinds of typical layered double hydroxides (Ni–Al,Co–Al LDH) are developed via scalable method. Two materials all display core–shell hierarchical structure. High specific capacitance of 2041 F g −1 and 1586 F g −1 are obtained for ZnCo 2 O 4 @Co–Al LDH and ZnCo 2 O 4 @Ni–Al LDH,respectively. Combining with active surface and synergistic effect, the role of hierarchical structure in enhancing performance is revealed. Moreover, two all solid state supercapacitors based on fabricated materials as positive electrodes, activated carbon as negative electrodes and PVA–KOH as polymer electrolyte are assembled. The maximum power and energy densities of ZnCo 2 O 4 @Co–Al LDH//AC are 6200 W kg −1 and 50.1 Wh kg −1 , respectively. While the power and energy densities of ZnCo 2 O 4 @Ni–Al LDH//AC are 3400 W kg −1 and 27.8 Wh kg −1 . At last, an energy storage–conversion system, based on solar cell as input device and assembled asymmetric supercapacitor ZnCo 2 O 4 @Co–Al LDH//AC as output device, is integrated as a self–sustaining power device, indicating its potential in practical applications.

From 1D nanotube arrays to 2D nanosheet networks on silver-coated textiles: new insights into the factors determining the performance of a core–shell hierarchical structure for wearable supercapacitors

Investigating the factors that determine the performance of the electrodes with different sub-structure helps to extend the application of wearable energy storage devices.

Cu2O templating strategy for the synthesis of octahedral Cu2O@Mn(OH)2 core–shell hierarchical structures with a superior performance supercapacitor

We demonstrate the design and fabrication of novel Cu2O@Mn(OH)2 core–shell hierarchical structures using octahedral Cu2O as a template.

Ultra-long life nickel nanowires@nickel-cobalt hydroxide nanoarrays composite pseudocapacitive electrode: Construction and activation mechanism

A three dimensional hierarchical composite electrode composed of nickel nanowires@nickel-cobalt double hydroxide aligned on nickel foam is successfully fabricated by an in-situ growth route. In this composite electrode, the nickel nanowires are used as core materials to support high-pseudocapacitance nickel-cobalt double hydroxide and construct the typical Ni nanowires core@Ni-Co double hydroxide shell hierarchical structure on Ni foam. Compared with Ni-Co double hydroxide/Ni foam electrode (without nickel nanowires), the electrochemical performance of the obtained composite electrode is apparently improved, which shows a high areal specific capacitance (2.25 F cm−2 at 5 mA cm−2), excellent rate capability (1.65 F cm−2 at 100 mA cm−2) and superior cycle stability (151.2% retained in the 20000th cycle). And the activation mechanism of ultra-long cycle life of the obtained composite electrode is studied in this work, which indicates that the transforms of surface atoms on Ni nanowires into high-pseudocapacitance Ni(OH)2 and NiOOH during cycles make major contributions for the performance improvement.

Formation of hollow Co3O4 nanocages with hierarchical shell structure as anode materials for lithium-ion batteries

Two kinds of unusually hollow and porous Co3O4 nanocages with high complexity in shell architecture and high surface areas of 58.8 and 43.8 m2 g−1 are synthesized by a straightforward pyrolysis of zeolitic imidazolate framework (ZIF-67) rhombic dodecahedrons as self-sacrificing template under different temperature. The two types complex hollow Co3O4 nanocomposites utilized as anode materials for Lithium ion batteries (LIBs) manifested the initial discharge capacities as high as 2169 and 1928 mA h g−1 and initial Coulombic efficiency under a specific current of 100 mA g−1, which could still show a high reversible capacity of 915 and 668 mA h g−1 after 100 cycles. The two electrodes materials also exhibited rate capability of 322 and 169 mA h g−1 at a large specific current of 2 A g−1. The hollow architecture, complex shell structure, high surface area and ultrafine building blocks might give rise to the high specific capacities. Moreover, the simple synthesis route rendered it to be a potential and promising electrode materials for rechargeable LIBs.

A novel nano-Sn particle/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)/poly(vinyl alcohol) core–shell hierarchical composite as high-performance anode material for lithium ion batteries

A novel nano-Sn particle/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)/poly(vinyl alcohol) core–shell hierarchical composite (nano-Sn/PEDOT:PSS/PVA CSHC) was fabricated for the first time and evaluated as a high-performance anode material in lithium ion batteries (LIBs). The core–shell hierarchical structure of the composite was revealed by field-emission scanning electron microscope and transmission electron microscope; the components of the composite were investigated by X-ray diffraction and fourier transform infrared spectroscopy; the nano-Sn particle content in the composite was obtained by thermogravimetric analysis and the electrochemical performance was studied by galvanostatic charge/discharge cycling tests and electrochemical impedance spectroscopy. When used as LIB anode material, the nano-Sn/PEDOT:PSS/PVA CSHC electrode exhibited high reversible capacity (568 mA h g−1 after 100 charge/discharge cycles at a current density of 100 mA g−1), superior cycling stability (capacity retention of 66.0 % after 100 cycles), good rate performance (143 mA h g−1 at 1500 mA g−1) and low charge transfer resistance compared to pristine nano-Sn particle and nano-Sn/PEDOT:PSS composite electrodes. The improved electrochemical performance can be attributed to the core–shell hierarchical structure. The results show that the nano-Sn/PEDOT:PSS/PVA CSHC is a promising anode candidate for next-generation LIBs.

Capsules with a hierarchical shell structure assembled by aminoglycosides and DNA via the kinetic path.

Aminoglycosides are capable of expelling water molecules when forming a complex with DNA via electrostatic interaction. The "water-proof" nature of the complex leads to the formation of capsules, which possess hierarchical shell structures with a smooth and rigid outer layer and a viscoelastic inner layer.

Template-free synthesis of homogeneous yolk–shell TiO2 hierarchical microspheres for high performance lithium ion batteries

The homogeneous yolk–shell TiO2 hierarchical microspheres (TiO2 HYSHMs) consisting of small nanoparticles have been fabricated through a facile template-free solvothermal reaction followed by calcination. The obtained samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, nitrogen adsorption/desorption analysis and Fourier transform infrared spectroscopy. It was found that the microspheres have porous shell (∼100 nm in thickness) composed of small nanoparticles with an average diameter of 10 nm. The interspace between the yolk and shell is ∼150 nm. The BET specific surface area and pore volume of the sample are 151.1 m2 g−1 and 0.23 cm3 g−1, respectively. Ostwald ripening processes are proposed to explain the growth mechanism of the TiO2 HYSHMs based on a series of time-dependent experiments. As the anode materials for the lithium ion batteries, TiO2 HYSHMs exhibit a high initial discharge capacity of 267.6 mAh g−1 at 0.25 C and retain 191 mAh g−1 even after 40 cycles, indicating good electrochemical performance. These good electrochemical performances could be attributed to the short Li-ion and electron pathways, and enough elastic buffer space to accommodate large volume variation of the special yolk–shell hierarchical structure.

Recyclable chestnut-like Fe3O4@C@ZnSnO3 core–shell particles for the photocatalytic degradation of 2,5-dichlorophenol

Numerous efforts have been made to integrate nanorods into 3D ordered multifunctional architectures. Herein, we report a rational design and the successful fabrication of a novel chestnut-like Fe3O4@C@ZnSnO3 core–shell hierarchical structure. Reactive Zn and Sn colloids obtained using laser ablation in liquids were used as non-ion precursors to intentionally grow ZnSnO3 nanorods onto the surfaces of core–shell Fe3O4@C particles under solvothermal conditions. The core–shell hierarchical structures were analyzed by scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray analysis (EDX), X-ray diffraction, and a superconducting quantum interference device magnetometer (Quantum Design MPMS). The results showed that the Fe3O4@C particles served as nucleation sites for the oriented growth of ZnSnO3 nanorods on the surfaces of the carbon layer. The synthesized core–shell composite exhibited cyclic photocatalytic ability toward the degradation of 2,5-dichlorophenol model molecules because of the compact assembly of the magnetic Fe3O4 core, the active ZnSnO3 photocatalyst, and a protective carbon layer.

Amorphous carbon nanotube–polyaniline core–shell nanostructures for efficient cold cathode applications

The general challenge to improve the field emission properties of conducting polymers depends on the fabrication of novel nanostructures from their polymeric aggregates and/or the synthesis of novel nanocomposites. Here we report amorphous carbon nanotube (aCNT)–polyaniline (PANI) core–shell hierarchical structures for the first time, which exhibit high field emission properties. The aCNT–PANI hierarchical nanostructures were prepared using a facile and cost effective method, which involved a simple in situ oxidative polymerization of aniline in the presence of aCNTs at three different temperatures. The as-synthesized samples were characterized using X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy and Raman spectroscopy. The field emission characteristics of the pristine aCNT sample were compared with the composites synthesized at different temperatures. The turn-on fields of the aCNT–PANI composites in comparison with the pristine aCNTs decreased from 9.13 to 2.57 V μm−1 and the emission current density increased from 0.031 to 1.27 mA cm−2 at an electric field of 11.50 V μm−1. The improvement in the field emission properties of the aCNT–PANI composites can be explained in terms of both a higher enhancement factor and a lower work function of the composite. This research gives a new perception towards the radical improvement of field emission properties of conducting polymers, based on unique hierarchical core–shell nanostructures.

Self-assembled 3D flower-like hierarchical Fe3O4/KxMnO2 core–shell architectures and their application for removal of dye pollutants

A simple method for fabricating hierarchical composite structures consisting of K-birnessite (KxMnO2) nanosheets on Fe3O4 microspheres was reported in this paper. The field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) measurements indicated that the size of the three-dimensional (3D) flower-like hierarchical microspheres was about 420 ± 5 nm and the shell was composed of nanosheets with a thickness of about 5 nm. The experimental parameters such as reaction time, reaction temperature and the concentration of KMnO4 used in the solution were investigated for the growth of the core–shell hierarchical structures. These core–shell composites exhibited excellent removal efficiency (over 98% for rhodamine B (RB) and 94% for methylene blue (MB)) and rapid separation from aqueous solution by an external magnetic field, taking advantage of the combined benefits of hierarchical structured KxMnO2 nanosheets and magnetic microspheres. In addition, the adsorption behavior of this new adsorbent fitted well with both Langmuir and Freundlich isotherms and the pseudo-second-order kinetic model. All the results demonstrate that the core–shell composites are effective adsorbents for the removal of dye pollutants and thus could provide a new platform for dye decontamination.

ChemInform Abstract: Controlling Electrostatic Co‐Assembly Using Ion‐Containing Copolymers : From Surfactants to Nanoparticles

AbstractReview: 121 refs.