Core-shell Micro Research Articles

3D Printed Microlattices of Transition Metal/Metal Oxides for Highly Stable and Efficient Water Splitting

AbstractDeveloping affordable electrocatalysts is crucial for driving the sustainable energy transition to green hydrogen. Here, a generalizable method known as polymer infusion additive manufacturing is reported for transforming 3D‐printed photopolymers into core–shell micro lattice electrodes for electrocatalytic water splitting with transition metal/metal oxides/carbon heterointerfaces. The optimized free‐standing architectures integrate Cu/CuOx on carbon (Cu/CuOx/C) microlattices, yielding high electrocatalytic activity (overpotential of 145 mV at 10 mA cm−2 and a Tafel slope of 134 mV dec−1) and excellent durability for the hydrogen evolution reaction (HER) (>100 h), surpassing state‐of‐the‐art Cu foams. Additionally, for the oxygen evolution reaction (OER), Co/CoOx on carbon (Co/CoOx/C) microlattices display exceptional activity with the lowest overpotential (1.40 V to gain 10 mA cm−2) among all reported PGM‐free electrodes. The study explores the gas phase mass‐transport properties of these 3D microlattices via microscopic imaging of bubble evolution, finding that the outstanding electrocatalytic performance and long‐term stability of microlattice electrodes leverages their mesoscale (100–300 µm) pores, providing accessibility of electrolytes, maximizing utilization of active sites, and ensuring rapid evolution of gas bubbles. Thus, a simple but pioneering method is introduced for manufacturing 3D mesostructured electrocatalysts with deep control of liquid and gas phase mass‐transport, enhancing the efficacy of alkaline water electrolysis.

Protective primers with reduced zinc powder content caused by the addition of core-shell micro talc/polyaniline pigment

This study aims to verify the possibility of replacing a portion of zinc (up to 30 wt.%) with a newly designed micro talc/polyaniline (PANI) core-shell pigment that can be used in the protective primer compositions for metals. Measurements of the electrode potential of painted steel and the electrical capacity of the steel/coating/electrolyte system showed that synthesized pigment bears two functions. Firstly, its presence in the epoxy-amine coatings provides a cathodic protection mechanism for steel with the lower zinc content. Secondly, it allows long-term preservation of the sacrificial metal activity and passive state of the substrate due to the autocatalytic redox cycle based on the reversible conversion of PANI from its emeraldine to leucoemeraldine form. The corresponding mechanism that allows the retaining of sacrificial metal activity and the passive state of the substrate is proposed.

Synthesis of petaloid and origami-lantern shaped MnO2/Co2CH@C hierarchical core-shell nanorod arrays for portable asymmetric supercapacitor

Freestanding electrodes fabricated with hierarchical core-shell micro-/nano-structured materials synthesized from redox-type metal oxides show enormous potential for portable electronic devices. In this, a novel and facile strategy for the preparation of petaloid and origami-lantern shaped MnO2/Co2CH@C hierarchical porous core-shell nanorod arrays is proposed. The fabricated electrode based on MnO2/Co2CH@C hybrid composite exhibits superior capability of 2022 mF cm−2 under high current density of 5 mA cm−2, which can be explained by the well-oriented petal-like and origami-lantern shaped nanosheets as well as the 3D core-shell porous hierarchical structure. Additionally, a solid-state asymmetric supercapacitor equipment is assembled on basis of the synthesized hierarchical MnO2/Co2CH@C hybrid, exhibiting an energy density of 15 Wh kg−1 at the power density of 255 W kg−1. Notably, the multifunctional instrument can be operated by the assembled device for 8 min, while monitoring time, temperature and air humidity in a portable outdoor environment. Moreover, a blue indicator can also be operated for 9 min long, evidencing their potential commercial applications. Overall, this work demonstrates the promising potential of the synthesized novel origami-lantern shaped and highly oriented hierarchical composites for electrochemical energy storage applications.

Product Modification in Catalytic Fast Pyrolysis of Corn Stalk: The Decoupled Effect of Acidity and Porosity within a Core–Shell Micro-/Mesoporous Zeolite

The large production of biomass waste is causing worldwide concern about its low-value application and toxic potential. Catalytic fast pyrolysis (CFP) is a promising method to convert biomass waste...

High-entropy alloy@air@Ni–NiO core-shell microspheres for electromagnetic absorption applications

Core-shell microspheres with high-entropy alloy (HEA: FeCoNiCrCuAl0.3) as core and metal oxide (Ni–NiO) as shell have been successfully constructed via a two-step hydrothermal method. The chemical composition, microstructure, electromagnetic (EM) properties and EM wave absorption properties were characterized in detail. We find that the magnetic loss originated from high-entropy alloy and the dielectric loss caused by Ni–NiO can promote the consumption of EM energy through synergistic effect. The effective absorption bandwidth (fE, RL < −10 dB) of HEA@air@Ni–NiO composites was 4.0 GHz with an ultra-thin matching thickness (d) of 1.3 mm. We believe that this HEA@air@Ni–NiO composite can be a new generation of high-efficiency high-entropy alloy based EM wave absorber because of its strong EM wave absorption capability under an ultra-thin matching thickness. In addition, the new preparation method of core-shell micro-/nanostructure also has important reference value.

Impact of Fat Replacement by Core-shell Microparticles on Set Type Yoghurts: Study of Their Physicochemical, Textural and Microstructural Properties

Background: Core-shell micro and nanoparticles can be used to encapsulate bioactive or functional components and to replace fat content also, since they are able to mimic the organoleptic characteristics of the fat globules. &lt;/P&gt;&lt;P&gt; Objective: The aim of this study was to investigate the effect of replacing milk fat matter by core-shell microparticles in set type yoghurt. &lt;/P&gt;&lt;P&gt; Method: Microparticles were produced by electrostatic deposition of carboxymethylcellulose (CMC) on thermally induced aggregates of &amp;#946;-lactoglobulin (&amp;#946;-lg)n. Laboratory made yoghurts were prepared with: full fat milk (F), low fat milk (L) and low fat milk with CS microparticles (CS). Yoghurts properties (e.g. physicochemical, rheological, textural) were characterized during storage at 4 &amp;#176;C. Trials were also conducted in commercial yoghurts taken as references. &lt;/P&gt;&lt;P&gt; Results: Water holding capacity (WHC) and elastic modulus (G´) of CS yoghurts resulted similar to commercial yoghurts. Color properties (L*, a*. b*) were slightly altered and showed no significant variation upon time. CS yoghurts behaved as a weak gel as indicated by the higher n values obtained from mechanical spectra and by the lower firmness obtained from texture measurements. Important differences were observed in microstructure. CS yoghurts showed homogeneous aspect with large aggregates and empty spaces. Bacterial growth in CS yoghurts resulted similar to low fat yoghurts. &lt;/P&gt;&lt;P&gt; Conclusion: Replacement of milk fat by core-shell microparticles would be feasible giving a final product without major differences, at least instrumentally measurable, to commercial yogurt.

Catalytic reduction of toxic dyes in the presence of silver nanoparticles impregnated core-shell composite microgels

Novel polystyrene-poly(N-isopropylmethacrylamide-acrylic acid) [PSTY-PNIPMA-ACC] core-shell micro particles were prepared by seed induced emulsion polymerization. Nano-Ag-PSTY-PNIPMA-ACC composite particles were synthesized by reduction of AgNO3 salt with reductant NaBH4 in the presence of water as medium and micro particles as template. The pure and composite micro particles were characterized by various techniques such as UV-visible spectroscopy (UV-vis) and Fourier transform infrared spectroscopy (FTiR) to illustrate their optical properties and structural hierarchies, respectively. Dynamic light scattering (DLS) analysis was performed to study the particles size distribution. TEM analysis shows that Ag NPs were monodispersed and equally distributed in spherical shaped shell of PSTY-PNIPMA-ACC micro particles. The prepared nano-Ag-PSTY-PNIPMA-ACC particles were used as catalyst in reduction of Rhodamine B (Rh-B) using NaBH4 as reductant. For comparative analysis, reduction of Rh-B was also performed in absence of nano-Ag-PSTY-PNIPMA-ACC catalyst and in the absence of NaBH4, respectively. Rh-B was only reduced in short time at feasible rate in presence of both composite micro particles and NaBH4. Degradation of Rh-B followed the pseudo first order kinetics and values of apparent rate constant (kapp) were come out to be 1.127 and 0.004min−1 with percentage degradation of 99.03 and 4.37%, respectively. Results showed that our prepared nano-Ag-PSTY-PNIPMA-ACC particles are promising catalysts. High catalytic activity of composite micro particles may be attributed to their core-shell type morphology, sieved shell, small sized Ag NPs restricted in shell region. Langmuir Hinshelwood mechanism was followed by degradation of dye. Optimum concentration for maximum degradation of Rh-B in small time interval was found 4.95 mM. Various other toxic dyes such as brilliant blue (Bb) and methylene blue (MB) were also reduced individually and simultaneously under same reaction conditions.

Core-Shell Medicated Nanoparticles Prepared Using Coaxial Electrospray for Fast Dissolution of Paracetamol

Background The dissolution of insoluble drugs is one of the most intractable challenges in pharmaceutics, particularly for those used to rapidly bring down a fever or stop pain. Advanced technologies are frequently introduced into this field for developing nano drug delivery systems (DDS) for this purpose. Methods Coaxial electrospray is a popular advanced process for creating core-shell micro-/nano-structures. Here, a core-shell nano DDS was fabricated and characterised in detail for enhancing the fast dissolution of paracetamol. A surfactant solution (consisting of 0.5% w/v Triton X-100% and 10% w/v polyvinylpyrrolidone (PVP) K10 in ethanol) and a drug solution (composed of 5% w/v paracetamol and 10% w/v PVP K10 in ethanol) were exploited. Results Under the selected conditions (an applied voltage of 20 kV, a collecting distance of 15 cm, and a shell-to-core fluid flow rate ratio of 0.5/1.5 mL/h), uniform core-shell nanoparticles were stably and continuously fabricated. Owing to the secondary interactions between PVP and paracetamol, the particles were amorphous composites, as verified by the XRD patterns and attenuated total reflectance–FTIR spectra. The nanoparticles could release the loaded cargoes within one minute after they were placed into the dissolution media. Conclusion Core-shell medicated nanoparticles prepared using coaxial electrospray can be an alternative approach for improving the dissolution rate of insoluble drugs. Acknowledgements Supported by the National Natural Science Foundation of China (No. 51373101).

Demonstration of (In, Ga)N/GaN Core–Shell Micro Light-Emitting Diodes Grown by Molecular Beam Epitaxy on Ordered MOVPE GaN Pillars

This work reports on the growth of (In, Ga)N core–shell micro pillars by plasma-assisted molecular beam epitaxy using an ordered array of GaN cores grown by metal organic vapor phase epitaxy as a template. Upon (In, Ga)N growth, core–shell structures with emission at around 3.0 eV are formed. With spatially resolved cathodoluminescence, an increasing In content toward the pillar top is found to be present in the (In, Ga)N shell, as indicated by a shift of CL peak position from 3.2 eV at the shell bottom to 3.0 eV at the shell top. Further, the fabrication of a core–shell pin structure is demonstrated. Spatially resolved electroluminescence measurements performed on individual pillars confirm electroluminescence from the (In, Ga)N shell (lateral diode) at around 3.0 eV, as well as from the pillar top facet (axial diode) at around 2.3 eV.

The interfacial effect of TiO2–Ag core–shell micro‐/nanowires on poly(arylene ether nitrile)

AbstractNovel TiO2–Ag core–shell micro‐/nanowires (TiO2 shell coating on Ag core) have been successfully prepared via a solvent–thermal method. Energy dispersive spectroscopy and X‐ray diffraction analyses revealed that the micro‐/nanowires were composed of Ag, Ti and O elements, and Ag was face‐centered cubic whereas TiO2 was mainly amorphous. Interestingly, scanning electron microscopy (SEM) and transmission electron microscopy results showed that most of the TiO2 bristles were perpendicular to and uniformly studded on the surface of the Ag cores. Subsequently, TiO2–Ag/poly(arylene ether nitrile) (PEN) composite films were prepared via a solution‐casting method in order to investigate the effect of TiO2–Ag on the PEN matrix. SEM images showed that there was good interfacial adhesion between fillers and PEN matrix owing to the special bristle‐like structure. Thermal analysis results showed that the TiO2–Ag/PEN composite films possessed excellent thermal properties endowed by the PEN matrix. The dielectric constant of the composite films increased to 9.3 at 100 Hz when the TiO2–Ag loading reached 40 wt%. Rheology measurements revealed that the network formed by TiO2–Ag was sensitive to shear stress and nearly time independent. © 2013 Society of Chemical Industry

Synthesis and study of carbon/TiO2 and carbon/TiO2 core–shell micro-/nanospheres with increased density

Abstract

Fabrication of Flake-Shaped Core-Shell Micro Particles by Way of Thermal Decomposition of Pentacarbonyl Iron on Diatomite Surface

In order to fabricate flake-shaped core-shell micro particles (FCMP) with light weight efficiently, deposition on diatomite was carried out by thermal decomposition. The deposition of Fe on diatomite was accomplished by thermal decomposition of pentacarbonyl iron (Fe(CO)5). The scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), and X-ray diffraction (XRD) are used to make clear their morphology microstructure, chemical composition, and crystal structure. The average diameter of FCMP is around 40μm, and the average aspect ratio is over 15. The main chemical composition of the FCMP is Fe, Si, Oand C. The XRD result revealed that crystal structures of the FCMP is close to α-Fe. The vibrant sample magnetometer (VSM) result revealed that the FCMP belong to soft magnetic material. The density test results show that the density of FCMP is close to the 2.6, which is lower than the density of pure carbonyl iron powder.

A novel hypurgia for cancer chemotherapy: Programmable release of antineoplastics and cytothesis agents from core–shell micro-/nano-particles

As one of the main cancer therapeutic methods, chemotherapy plays a vital role in clinical practice. However, when killing the cancerous cells, the chemotherapy drugs also damage the normal cells. Side effects are still urgent problems to be solved. Cytothesis agents, like hepatocyte growth factor, can stimulate cell mitotic division and promote regeneration of blood vessel endothelium and cell migration. In this hypothesis, an adjuvant strategy for chemotherapy is proposed: the anticancer drugs and the cytothesis agents release sequentially, thus the cytothesis agents can work following the anticancer drugs killing tumor cells thoroughly, to promote normal cells proliferation. The programmable release can be achieved through micro-/nano-particles with core-shell structures that simultaneously encapsulate the two different agents in the core and shell regions, respectively. Owing to the advantages of concentrated effects, convenience, and especially its controllability, the hypothesis has potential applications in cancer chemotherapy.