Shell Nanoparticles Research Articles

Phase controlled Fe2N@Fe3O4 core-shell nanoparticles hybridized with nitrogen-doped reduced graphene oxide for boosted charge transfer in asymmetric supercapacitor

Due to environmental concerns and requirements for sustainable development, there are increasing demands for electrode materials with high energy density in supercapacitors, utilizing earth-abundant materials. In that response, we designed a novel composite material by hybridizing core–shell nanoparticles (NPs), which were composed of iron oxide (Fe3O4) and its derivative iron nitride (Fe2N) as plentiful elements in the earth crust or air, with nitrogen-doped reduced graphene oxide (NrGO). The electrode prepared with the Fe2N@Fe3O4 NPs/NrGO demonstrated outstanding specific capacitance of 341.3 F g−1 at 0.5 A g−1, along with an improved rate capability approximately 4 times higher than that of pristine Fe3O4 NPs/GO. Also, the Fe2N@Fe3O4 NPs/NrGO exhibited stable performance within a wide potential range of −1.05 to 0.15 V and excellent cycle stability of 91.2 % at 5 A g−1 after 10,000 cycles. These exceptional characteristics might be attributed to the enhanced electrical conductivity and increased surface area of the material, achieved through the simultaneous formation of the NrGO from the GO and the phase-transformed Fe2N from the pristine Fe3O4 in a monolithic nitridation process. In addition, the core–shell hybrid was used for an asymmetric supercapacitor (ASC) anode, and it exhibited a wide potential range of 1.65 V and a maximum energy density of 28.6 Wh kg−1 at a power density of 825.0 W kg−1. Moreover, a green LED was successfully powered by the serial connection of two ASCs. These results and demonstrations prove that our strategies for designing materials composition, hybrid heterostructure, and core–shell configuration are highly effective in improving energy density, making them promising and economical next-generation energy device materials utilizing earth-abundant elements (e.g. Fe, O, N).

The Optical and Structural Properties of the Fe@Au Core–Shell Nanoparticles Prepared by PLAL

In this research, metal targets dipped in 3 mL of distilled water (DW) were subjected to pulsed laser ablation. Colloidal dispersions of Fe and Au, and bimetallic Fe@Au core/shell nanoparticles are created. The core/shell structure of these particles was subsequently studied using X-ray diffraction. UV–Vis and HRTEM measurements are used to determine surface Plasmon resonance (SPR) and particle sizes. We also carried out an investigation to gauge the stability in terms of the surface charge of the produced nanoparticles (Zeta-potential). The findings show that maximum absorption value of Fe Nps was 0.45 in the range (200–350) nm, while Au exhibits a surface Plasmon resonance (SPR) peaked at a wavelength of 545 nm in the range (290–1100) nm. Another peak was noticed at (555) nm for the surface Plasmon band of the particles Fe@Au in the range (290–1100) nm, HRTEM measurement was used to check the shape and particle size, and the results showed that the average particle size was less than 50 nm.

Conductive polyacrylate coatings filled with bimetal Cu–Ni, Zn–Cu, or Zn–Ni powders and graphene nanoplatelets

AbstractConductive coatings on a glass substrate are widely used in electronics and automotive, ship, aircraft, and optical industries. The method for obtaining electroconductive polyacrylate coatings filled with bimetal Cu–Ni, Zn–Cu, or Zn–Ni particles and graphene nanoplatelets (GNPs) is developed in this work. At the ratio GNPs:bimetal powder:polymer of (33–35):(17–35):(30–50) (wt%) and the coating thickness 50 μm specific volume resistance is 0.12–0.26 Ω·cm owing to the percolation effect. Bimetal particles are synthesized by nickel or copper ions reduction from aqueous solutions on copper or zinc particles. Their composition is regulated by the duration of metal ions reduction. Bimetal particles have a structure of copper or zinc core with a loose shell of nickel or copper nanoparticles, they ensure the contact between GNPs forming a continuous network in polymer matrix. GNPs are obtained by thermal exfoliation of natural flake graphite treated in liquid ammonia containing metal sodium. Polymer composite is prepared using the solution of methyl‐ and n‐butylmethacrylate copolymer. Coatings have adequate adhesion to the glass, and owing to their high conductivity, absence of noble metals, simplicity and cheapness of fabrication can be used for production of conductive elements on glass and other substrates.Highlights Cu–Ni, Zn–Cu, or Zn–Ni powder and GNPs filled conductive polyacrylate coatings Bimetal core‐shell particles are obtained by Ni(II) or Cu(II) reduction in solutions Bimetal particles and GNPs form a network in polymer with percolation effect Specific volume resistance of coatings 50 μm thick on glass is 0.12–0.26 Ω·cm Coatings conductivity and adhesion to glass open great prospects for application

Optimization of Core–Shell Nanoparticles Using a Combination of Machine Learning and Ising Machine

Machine‐learning‐based optimization techniques are widely used for designing complex materials. However, an efficient search for the complex systems, where a combinatorial explosion occurs in the materials search space, is still challenging. Core–shell nanoparticles (CSNPs) are an example of a complex system with a high degree of freedom owing to their complicated structure and multiple constituent materials. In this study, a new black box optimization technique is developed. In this method, the structure of the CSNPs is optimized using an Ising machine and their constituent materials are selected using Bayesian optimization with the optical properties of the materials as the “descriptors”. Aiming for applications to i‐line photolithography, the authors search for CSNPs that are transparent to ultraviolet light of wavelength 355–375 nm and opaque to visible light of wavelength 400–830 nm. The transmittance spectra of the nanoparticles are obtained using a Mie theory calculator. The proposed nanoparticles with the best optical properties have a multilayered structure with a radius of approximately 40 nm and an outer shell composed of either Mg or Pb. The results indicate that a combination of various optimization techniques is more efficient in discovering the better complex materials.

Growth and property evaluation of nickel–graphite core–shell nanoparticles based on temperature parameters for utilization in silver paste

Growth and property evaluation of nickel–graphite core–shell nanoparticles based on temperature parameters for utilization in silver paste

Asymmetric nanoparticle oxidation observed in-situ by the evolution of diffraction contrast

The use of transmission electron microscopy (TEM) to observe real-time structural and compositional changes has proven to be a valuable tool for understanding the dynamic behavior of nanomaterials. However, identifying the nanoparticles of interest typically require an obvious change in position, size, or structure, as compositional changes may not be noticeable during the experiment. Oxidation or reduction can often result in subtle volume changes only, so elucidating mechanisms in real-time requires atomic-scale resolution or in-situ electron energy loss spectroscopy, which may not be widely accessible. Here, by monitoring the evolution of diffraction contrast, we can observe both structural and compositional changes in iron oxide nanoparticles, specifically the oxidation from a wüstite-magnetite (FeO@Fe3O4) core–shell nanoparticle to single crystalline magnetite, Fe3O4 nanoparticle. The in-situ TEM images reveal a distinctive light and dark contrast known as the ‘Ashby-Brown contrast’, which is a result of coherent strain across the core–shell interface. As the nanoparticles fully oxidize to Fe3O4, the diffraction contrast evolves and then disappears completely, which is then confirmed by modeling and simulation of TEM images. This represents a new, simplified approach to tracking the oxidation or reduction mechanisms of nanoparticles using in-situ TEM experiments.

One-pot synthesis of iron core—iron oxide shell nanoparticles with potential for magnetic imaging

One-pot synthesis of iron core—iron oxide shell nanoparticles with potential for magnetic imaging

A revisit to the quasistatic analysis of hyperbolic metamaterial supported core-shell nanoparticle

A study of the interaction of light with a certain kind of nanoparticle –a core–shell nanoparticle with the shell being of the multilayer hyperbolic metamaterial (HMM) kind–was reported before (Baqir et al. (2021)). However, the study had certain limitations regarding the choice of filling fraction used in the construction of the HMM shell. Herein, the constraints were highlighted and an attempt was made to obtain an appropriate formula for the effective dielectric function of the system for the case ɛt/ɛr<−1/8, where ɛr and ɛt being the radial and tangential components of HMM relative permittivity.

Effective utilization of cashew nut shell pyro oil blended with optimum amount of Al2O3 and TiO2 nanoparticles in DI engine

The present research activity's major objective is to improve the performance and emission characteristics of diesel engines that burn pyro oil and cashew nut shell nanoparticles. This work identifies the nanoparticles that should be added to cashew nut shell pyro oil to allow it to be utilized efficiently in compression ignition engines. In this experiment, the two nanoparticles, Al2O3 and TiO2, were mixed with cashew nut shell pyro oil. For testing purposes, nanoparticles were combined with cashew nut shell pyro oil at various concentrations, including 150 and 200 ppm. The criterion for picking the best combination was stability. To improve the optimal performance of the nanoparticle-blended oil, the cashew nut shell pyro oil was emulsified. The nanoparticles, which also act as an enhancing agent, speed up the combustion process. The combination of pyro oil, cashew nut shell emulsion, and nanoparticles improved performance and reduced emissions. The brake thermal efficiency values for 200 ppm Al2O3 and TiO2 mixed emulsified cashew nut shell pyro oil were 29.6% and 29.4%, respectively, whereas the values for diesel and cashew nut shell pyro oil were 31.6% and 29.8%. When comparing cashew nut shell pyro oil to oil with 200 ppm Al2O3 and TiO2, the smoke value was found to be reduced by 58.8% and 56.7%, respectively. It was discovered that cashew nutshell pyro oil with 200 ppm Al2O3 and TiO2 had 35.3% and 34.96% reduced hydrocarbon emissions respectively.

Thermo-Responsive Hydrogels Encapsulating Targeted Core-Shell Nanoparticles as Injectable Drug Delivery Systems.

As therapeutic agents that allow for minimally invasive administration, injectable biomaterials stand out as effective tools with tunable properties. Furthermore, hydrogels with responsive features present potential platforms for delivering therapeutics to desired sites in the body. Herein, temperature-responsive hydrogel scaffolds with embedded targeted nanoparticles were utilized to achieve controlled drug delivery via local drug administration. Poly(N-isopropylacrylamide) (pNIPAM) hydrogels, prepared with an ethylene-glycol-based cross-linker, demonstrated thermo-sensitive gelation ability upon injection into environments at body temperature. This hydrogel network was engineered to provide a slow and controlled drug release profile by being incorporated with curcumin-loaded nanoparticles bearing high encapsulation efficiency. A core (alginate)-shell (chitosan) nanoparticle design was preferred to ensure the stability of the drug molecules encapsulated in the core and to provide slower drug release. Nanoparticle-embedded hydrogels were shown to release curcumin at least four times slower compared to the free nanoparticle itself and to possess high water uptake capacity and more mechanically stable viscoelastic behavior. Moreover, this therapy has the potential to specifically address tumor tissues over-expressing folate receptors like ovaries, as the nanoparticles target the receptors by folic acid conjugation to the periphery. Together with its temperature-driven injectability, it can be concluded that this hydrogel scaffold with drug-loaded and embedded folate-targeting nanoparticles would provide effective therapy for tumor tissues accessible via minimally invasive routes and be beneficial for post-operative drug administration after tumor resection.

Magnetite core and ZnO shell – What is in between and how does it affect on nanoparticles properties?

Fe3O4 superparamagnetic nanoparticles are one of the most promising material for MRI T2 contrast agent production. Today a problem still exist with magnetite nanoparticles stabilization and protection against the loss of magnetic properties due to the oxidation process. Present work is devoted to the study of the Fe3O4 nanoparticles with ZnO protective shell focusing on the impact of shell properties and the impact of shell synthesis conditions on magnetic properties of the obtained core–shell nanoparticles, including the formation and transformation of transition layer between magnetite and shell.Magnetic core–shell nanoparticles Fe3O4@ZnO were obtained by two different synthesis procedures at three different temperatures to impact shell formation process. All samples were thoroughly characterized with complex of physical and chemical methods, including XRD, FTIR, HR-TEM, BET, DLS, VSM and TGA-DSC measurement. Computer simulations and Mössbauer spectroscopy were engaged to understand the processes occurring between the core and the shell during the shell formation.ZnO shell was successfully synthesized over the magnetite NPs surface, the shell is thick enough to protect magnetite surface from the environment. Presence of an transition layer, which composition depends on the synthesis procedure, was revealed. Correlations between magnetic and thermal characteristics and transition layer composition were found. MRI in vitro experiments have shown that T2 relaxation times decrease with increase of shell density.

Cobalt-Doped Pd@Pt Core–Shell Nanoparticles: A Correlative Study of Electronic Structure and Catalytic Activity in ORR

Cobalt-Doped Pd@Pt Core–Shell Nanoparticles: A Correlative Study of Electronic Structure and Catalytic Activity in ORR

Synthesis of silver nanoparticles with polyols under reflux and microwave irradiation conditions

Four polyols were used as stabilisers to synthesise silver nanospheres under reflux and microwave irradiation conditions. The nanoparticles were covered with a protective up to 10 nm silicon dioxide shell. The shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) technique was used to analyse the self-assembled monolayer of 4-mercaptobenzoic acid (4-MBA) by applying the produced silver core-silica shell nanoparticles. The article provides a detailed description of the synthesis, analysis and application of the nanoparticles based on UV/Vis, HR-TEM and SHINERS data.

Precise tuning of silica pore length and pore diameter on silica-encapsulated gold core–shell nanoparticles and catalytic impact

The ability to individually tune the pore length and pore diameter of silica-encapsulated gold core–shell nanoparticles (CSNPs) via a seeded encapsulation method is demonstrated and their impact on catalysis determined. Reducing the solvent volume during the shell growth phase resulted in CSNPs with shells of increasing thickness from 75 nm to 202 nm, following a linear relationship. The addition of 1, 3, 5-triisopropylbenzene (TIB) during synthesis increased the average pore diameter from 25 Å to 32 Å by swelling the pore template, swelling further to 38 Å when adding both TIB and n-decane. By decoupling the gold core reduction and silica condensation stages, gold core diameters were largely unaffected by silica growth reaction conditions. This was achieved by encapsulating CTAB-stabilized nanoparticles rather than reducing and stabilizing the nanoparticles during silica condensation. When used to catalyze solvent-free benzyl alcohol oxidation, it was found that CSNPs with increasing shell thicknesses demonstrated increased formation of the desirable aldehyde product, holding the undesired ester product yield constant. In contrast, CSNPs with increasing pore diameter exhibit increased formation of both aldehyde and ester products unselectively. These results—uniquely observed through the parametric isolation of pore length and diameter—suggest the reactant concentration at the pore wall due to hydrogen bonding, forming concentric “microphases” within the pores.

Polymer–lipid hybrid nanoparticles as potential lipophilic anticancer drug carriers

Nanocarrier systems are widely used for drug delivery applications, but limitations such as the use of synthetic surfactants, leakage of toxic drugs, and a poor encapsulation capacity remain as challenges. We present a new hybrid nanocarrier system that utilizes natural materials to overcome these limitations and improve the safety and efficacy of drug delivery. The system comprises a biopolymeric shell and a lipid core, encapsulating the lipophilic anticancer drug paclitaxel. Bovine serum albumin and dextran, in various molecular weights, are covalently conjugated via Maillard reaction to form the shell which serves as a stabilizer to maintain nanoparticle integrity. The properties of the system, such as Maillard conjugate concentration, protein/polysaccharide molar ratio, and polysaccharide molecular weight, are optimized to enhance nanoparticle size and stability. The system shows high stability at different pH conditions, high drug loading capacity, and effective in vitro drug release through the trigger of enzymes and passive diffusion. Serine proteases are used to digest the protein portion of the nanoparticle shell to enhance the drug release. This nanocarrier system represents a significant advancement in the field of nanomedicine, offering a safe and effective alternative for the delivery of lipophilic drugs.Graphical abstract

Fabrication of Fe3O4 core-TiO2/mesoSiO2 and Fe3O4 core-mesoSiO2/TiO2 Double Shell Nanoparticles for Methylene Blue Adsorption: Kinetic, Isotherms and Thermodynamic Characterization.

Herein, Fe3O4 core-TiO2/mesoSiO2 and Fe3O4 core-mesoSiO2/TiO2 double shell nanoparticles were prepared by first (R1) and second (R2) routes and applied for the removal of methylene blue. The reported adsorption capacities for R1-0.2, R1-0.4 and R2 samples were 128, 118 and 133 mg.g-1, respectively, which were obtained after 80 min as equilibrium contact time, and pH of 6 using a methylene blue concentration of 200 ppm. The adsorption of methylene blue using the prepared Fe3O4 core-meso SiO2/TiO2 double shell was analyzed by kinetic and isotherms models. In addition, thermodynamic investigations were applied to assess the spontaneous nature of the process. The obtained results confirmed that the pseudo-second order model is well fitted with the adsorption data and the Freundlich-isotherm assumption suggested a multilayer adsorption mechanism. In addition, results of the thermodynamic investigation indicated that ΔG° was in the range of -2.3 to -6.8 kJ/mol for R1-0.2, -2.8 to -6.3 kJ/mol for R1-0.4 and -2.0 to -5.2 kJ/mol for R2. In addition, the ΔH° and ΔS° values were found in the range of 26.4 to 36.19 kJ.mol-1 and 94.9 to 126.3 Jmol-1 K-1, respectively. These results confirm that the surfaces of Fe3O4 core-mesoSiO2/TiO2 and Fe3O4 core-TiO2/mesoSiO2 double shell exhibit a spontaneous tendency to adsorb methylene blue from the aqueous solutions. The achieved performance of Fe3O4 core-meso SiO2/TiO2 and Fe3O4 core-TiO2/meso SiO2 double shell as adsorbent for methylene blue removal will encourage future research investigations on the removal of a broad range of contaminants from wastewater.

Solution Self-Assembly of Amphiphilic Tadpole-like Giant Molecules Constructed by Monotethering Diblock Copolymer Chain onto a Nanoparticle.

The self-assembly behavior of a tadpole-like giant molecule (TGM) constructed from a hydrophobic nanoparticle (NP) monotethered by a single amphiphilic AB diblock copolymer chain was investigated by combining self-consistent field theory and density functional theory in solution. The effects of the hydrophobicities of the B blocks and NPs (i.e., solvent properties) on the self-assembly behavior of the TGMs were investigated in the cases of weak and strong intramolecular interactions (i.e., incompatibilities) between the components of giant molecules, respectively. Besides conventional ordered aggregates (such as spheres, rings, and vesicles) with hydrophobic B-cores covered by NP shells, several aggregates with novel hierarchical structures, including vesicles with NP-inserted hydrophobic walls, bead-string-like micelles, and long cylindrical micelles with NP bumps, were obtained by tuning the solvent properties under different intramolecular interactions. Noteworthy that the simulation results show that the arrangement of the NP bumps on the long cylindrical micelles may have a certain degree of helicity, which means that these micelles may have some unique electromagnetic features such as circular dichroism. Phase diagrams as a function of the hydrophobicities of the B blocks and NPs were constructed to show the formation conditions of these novel structures. These findings can not only offer new insights into understanding of the self-assembly behavior of the TGM in solution but also provide useful guidance for simple and efficient regulation of the morphology, as well as the NP distribution and arrangement of the ordered aggregates in experiments.

Confinement-enabled infusion-alloying of iron into platinum nanoparticle for core-shell PtFe@Pt intermetallic electrocatalyst

Platinum-based intermetallics are efficient electrocatalysts for the oxygen reduction reaction (ORR) in polymer electrolyte fuel cells (PEFCs) because of their high catalytic activity and durability. However, conventional manufacturing methods are complex and require high-temperature heat treatment, resulting in reduced uniformity in particle size and composition. Therefore, a facile and efficient synthesis method was developed for intermetallic PtFe@Pt core–shell nanoparticles using ultrasound-assisted coating of FeOx and subsequent post-treatment. Fe atoms in the oxide coatings of Pt@FeOx/C samples were incorporated into the Pt lattices as the heat-treatment temperature increased, resulting in the formation of random PtFe alloy cores at 400 °C and intermetallic PtFe alloy cores at temperatures above 600 °C. Interestingly, PtFe@Pt/C samples annealed at different temperatures had similar particle sizes (5–6 nm) and their PtFe cores were enclosed in 1–2 layers of Pt shells. Electrochemical analysis indicated that compared to the random PtFe core, the intermetallic PtFe core exhibited superior ORR performance owing to the modification of the Pt electronic structure. Additionally, increasing the chemical ordering parameters of the intermetallic PtFe core improved durability. Therefore, ultrasound-assisted metal oxide coating is a promising approach for synthesizing advanced electrocatalysts and, consequently, enhancing the commercial viability of PEFCs as clean energy converting systems.

Magnetoelectric Core–Shell Nanoparticle–Based Wearable Hybrid Energy Harvesters for Biomedical Applications

In this work, a novel barium titanate–coated cobalt ferrite core–shell magnetoelectric nanoparticle and poly(3,4‐ethylenedioxythiophene): polystyrene sulfonate–based wearable energy‐harvesting patch for wireless power‐transfer applications are proposed. The developed flexible patch has unique ease of fabrication and high‐efficiency energy conversion capability from the magnetic field and mechanical motion to the electric field as compared to bulk or thin‐film‐based devices. This unique power‐transfer capability of this device is achieved due to the crystalline nature of fabricated nanoparticles, which is confirmed using X‐ray diffraction and high‐resolution transmission electron microscopy. This wearable patch can generate a high voltage of 560 mV when exposed to a 40 μT alternating magnetic field at the resonance frequency of 48.6 kHz. The hybrid mode of electric power generation is achieved by coupling bodily motion with the remotely applied alternating magnetic field (40 μT), which results in the generation of a higher electric potential of 860 mV and maximum power density of 0.458 mW cm−3 across a 10 kΩ load. The maximum magnetoelectric coefficient is recorded as 1300 mV cm−1 Oe−1. The flexible nature and hybrid operation of the proposed device make it an efficient alternative for powering a wide range of wearable medical electronic devices.

Properties of core–shell nanoparticles based on PLGA and human serum albumin prepared by different methods

Core–shell nanoparticles with poly(lactide-co-glycolide) cores and human serum albumin shells (PLGA/HSA NPs) were prepared by three methods: by interfacial embedding of HSA in the PLGA NP surface during their formation and by adsorption or conjugation of HSA on pre-prepared PLGA NPs. All methods yielded PLGA/HSA NPs with a size of 130–150 nm and a narrow size distribution. In vitro fluorescence microscopy revealed the integrity of all core–shell systems when internalized in GL261 cells.