Core Shell Heteronanostructures Research Articles

A study of exchange bias effect in Fe3O4/MnO core–shell hetero-nanostructures

A study of exchange bias effect in Fe3O4/MnO core–shell hetero-nanostructures

Photocontrol of Exchange Bias Using Cobalt–Iron Prussian Blue Analogues for Applications in Spintronics

Multiphysics manipulation of the exchange bias (EB) effect to achieve spin-valve-type spintronic device versatility has begun to attract increasing attention recently. Light-controlled EB is considered to be an attractive approach because the photon mode allows access to a wide variety of materials with high speed, remote control, noncontact, and superior resolution. In this work, we report a detailed photocontrolled EB effect in the well-defined CoO@CoFePBA core–shell heteronanostructure, where the EB effect of this composite can be permanently changed after being exposed to light. As demonstrated, such an interesting photocontrolled effect is actually affected by the composition of the CoFePBA shell. More deeply, the alkali-metal-ion content in the CoFePBA shell is the major factor in controlling these hybrids’ EB effects. Different alkali-metal insertions result in different ratios of the FeIII–CoII magnetic pair to the FeII–CoIII diamagnetic pair in the CoFePBA shell, where FeIII–CoII and FeII–CoIII control the magnetic and photomagnetic effects of CoFePBA, respectively. Therefore, the photocontrolled EB effect of the whole nanohybrid can be adjusted by the amount of alkali-metal insertion in the CoFePBA shell. This study is an advance in the research of light-controlled EB effects, which are useful for the evolution of new functional spintronic devices, such as photomagnetic switches, photomagnetic sensors, and photointelligent information storage materials.

Thermally controlled structural strain reduction in core shell magnetoelectric nanocomposite

In this research, we have presented detailed studies of the effect of temperature-controlled hydrothermal fabrication techniques on the morphology and structural strain in magnetoelectric core-shell nanocomposite having magnetic CoFe2O4 core coated with a piezoelectric BaTiO3 shell. We have presented the effect of controlled cooling rate during annealing process of synthesis on the structural integrity and structural strain of the core-shell hetero-nanostructure. Using temperature controlled hydrothermal method, it has been observed that controlling the cooling rate to 20 °C/min while annealing process leads to low structural strain on the deposited BaTiO3 shell. This also leads to high structural integrity of the fabricated heterostructure nanocomposite. To measure the strain distribution in the coated shell, geometric phase analysis was performed on the high-resolution transmission electron microscopic image of the fabricated core-shell nanostructure. Semi quantitative Energy-dispersive X-ray spectroscopy line scan elemental mapping have confirmed the elemental distribution throughout the nanostructure and formation of the core–shell structure. Moreover, through the geometric phase analysis, the core and the shell can be distinctively visualized which confirms the homogeneity of the coating of single crystalline BaTiO3 shell on the CoFe2O4 core.

A versatile core–shell hetero-nanostructure catalysed chemo-selective synthesis of β-enamino carbonyl compounds

A core–shell hetero-nanostructure has been developed and used for the enamination of β-carbonyl compounds.

Tunable Optical Response Based on Au@GST Core–Shell Hetero-nanostructures

Tunable Optical Response Based on Au@GST Core–Shell Hetero-nanostructures

Direct growth of highly organized, 2D ultra-thin nano-accordion Ni-MOF@NiS2@C core-shell for high performance energy storage device

Metal-organic framework (MOF) as an active material is a state-of-the-art challenge to improve performance of energy storage devices due to its high porosity, ion diffusion channel and provision of redox sites. Nevertheless, the development of next-generation devices requires overcoming shortcomings such as low electrical conductivity and low MOF stability. Herein, the in situ growth of a nickel-based MOF on a Ni foam and the formation of a Ni-MOF@NiS2@C (NMSC) core-shell hetero-nanostructure is reported to overcome the challenge of using MOFs as active materials. Additionally, a surfactant-assisted approach is demonstrated to construct an ultra-thin 2D nano-accordion structure with interstitial gaps between the nanosheets. The unique nano-accordion structure facilitates faster ion diffusion and decreases the total resistance owing to the excellent charge transfer ability. In particular, the solid-state flexible supercapacitor exhibited a high performance with a specific capacitance of 283.5 F g−1 with an excellent energy density of 77.2 W h kg−1 at a power density of 7000 W kg−1.

Mesoporous SiO2-derived g-C3N4@CdS core-shell heteronanostructure for efficient and stable photocatalytic H2 production

Semiconductor-based heteronanostructures with wide light absorption and efficient electron-hole separation properties exhibit great potential for photocatalytic applications. Here we employ the mesoporous SiO2 nanoparticles as the template to simultaneously exfoliate the nano-confined g-C3N4 and deposit the CdS nanoparticles to form a series of core-shell SiCN@CdS heteronanostructures for photocatalytic H2 production under the visible light irradiation. Based on the physicochemical characterizations, we have been able to discuss the compositions, structures, and properties of the core-shell photocatalysts. Benefiting from the optimized equilibrium state of a relative high specific surface area, light absorption, crystalline degree, and a homogeneous dispersion of the outer CdS nanoparticles, the SiCN@2CdS exhibits the highest photocatalytic activity and stability for H2 production under the visible light irradiation. Results also suggest that the existence of the SiO2 template is benefit to suppress the aggregation and improve the recyclability of the core-shell photocatalysts when they are applied in the aqueous phase. The present study suggests a new sight on the template-assisted designing and synthesizing high-reactive, low-cost, environmental-stable, and easy-recyclable photocatalysts by precisely controlling the microstructures.

Enhanced photoexcited carrier separation in CdS–SnS2 heteronanostructures: a new 1D–0D visible-light photocatalytic system for the hydrogen evolution reaction

CdS–SnS2 1D–0D core–shell heteronanostructures were designed for an efficient visible-light photocatalytic H2 evolution reaction.

Shape-controlled Pd nanocrystal–polyaniline heteronanostructures with modulated polyaniline thickness for efficient electrochemical ethanol oxidation

A facile synthesis method for shape-controlled Pd NC–PANI core–shell heteronanostructures with controllable PANI thickness for efficient electrochemical ethanol oxidation.

Investigation of γ-AlOOH and NiWO4-coated boehmite micro/nanostructure under UV/visible light photocatalysis

A large-scale boehmite (γ-AlOOH) sphere and NiWO4-coated boehmite micro/nanostructured materials were synthesized via a facile two-step hydrothermal method with microwave irradiation using a solution phase route. The morphologies and structures of the prepared samples were characterized by scanning electron microscopy, high-resolution transmission electron microscopy (HR-TEM), X-ray diffraction, Fourier transform infrared spectroscopy, and energy-dispersive X-ray spectroscopy, and their optical and photocatalytic properties were also measured. The samples boehmite, AN1 and AN2 (different concentrations by NiWO4) were evaluated under UV/visible-light irradiation, and the AN1 sample showed intense (92.6%) degradation of methyl blue dye of the three samples. This enhancement was explained reasonably by HR-TEM evaluated surface-coated core–shell structured γ-AlOOH@NiWO4 shell width was about 10–15 nm and the core–shell size 120 nm. From the optical analysis, the core–shell heteronanostructure new energy level was attributed to the synergistic effect between NiWO4 and boehmite. In particular, a down-conversion luminescence process at the 450 nm excited energy optimization of redox for the efficient photogeneration of electron–hole pairs. Additionally, trapping measurement showed that O2·− and OH· species generated in the photocatalytic process played a key role in the degradation reaction. Based on these findings, this approach may offer a new strategy for the fabrication of surface-controlled spheres of core/shell structure-based photocatalysts with enhanced efficiency for environmental remediation applications.

Fabrication of core@interface:shell structured CuS@CuInS2:In2S3 particles for highly efficient solar hydrogen production

The ultimate goal of this study was to synthesize core-shell hetero-nanostructures for efficient charge separation during photocatalytic reactions. This is expected to result in increased photocatalytic activity. A core@shell structured CuS@In2S3 was proposed for solar hydrogen production with CuInS2 as an interface between the CuS and In2S3 components. The formation of the CuInS2 interface was confirmed from the XRD and HRTEM analysis. The introduction of the CuInS2 interface resulted in sulfur vacancies on the surface of the photocatalyst, which in turn increased the reactant active sites. In particular, it behaved like an electron trap to retard electron-hole recombination, so that it could eventually improve the photocatalytic activity. The designed CuS@CuInS2:In2S3 photocatalyst exhibited a hydrogen production of 2000 μmol/g after 10 h. Photoluminescence, photocurrent and IMVS measurements validated the enhanced photoactivity which was due to both the reduced recombination rate between the excited electron and hole pairs (e−/h+), and the rapid electron transfer in the core@interface:shell structured CuS@CuInS2:In2S3 photocatalyst.

Smart Hybridization of Au Coupled CdS Nanorods with Few Layered MoS2 Nanosheets for High Performance Photocatalytic Hydrogen Evolution Reaction

Fabrication of core–shell heteronanostructures with excellent optical properties and light induced charge separation effects have recently emerged as promising materials for solar to hydrogen conversion. Here, one-dimensional CdS–Au/MoS2 hierarchical core/shell heteronanostructures (CSHNSs) have been successfully synthesized by a facile two-step hydrothermal method. Such heteronanostructures exhibit high efficiency and excellent stability toward hydrogen production. The introduction of Au nanoparticles on to CdS nanorods not only made a Schottky junction with strong plasmonic absorption enhancement but also directed the growth of few layered MoS2 nanosheets as a hierarchical protective shell around the CdS nanorods. These CdS–Au/MoS2 hybrid structures possess a large number of edge sites in the MoS2 layers which are active sites for hydrogen evolution reaction. As a result, the CdS–Au/MoS2 CSHNSs exhibit outstanding hydrogen evolution performance which is 7 times that of pure CdS nanorods. Also these CdS–...

Synthesis of TiO2@α-Fe2O3 core–shell heteronanostructures by thermal decomposition approach and their application towards sunlight-driven photodegradation of rhodamine B

TiO2@α-Fe2O3 core–shell heteronanostructures that act as a good photocatalyst for the degradation of RhB were synthesized by a novel thermal decomposition approach.

Plasmon Modes Induced by Anisotropic Gap Opening in Au@Cu2 O Nanorods.

Integration of semiconductors with noble metals to form heteronanostructures can give rise to many interesting plasmonic and electronic properties. A number of such heteronanostructures have been demonstrated comprising noble metals and n-type semiconductors, such as TiO2 , ZnO, SnO2 , Fe3 O4 , and CuO. In contrast, reports on heteronanostructures made of noble metals and p-type semiconductors are scarce. Cu2 O is an unintentional p-type semiconductor with unique properties. Here, the uniform coating of Cu2 O on two types of Au nanorods and systematic studies of the plasmonic properties of the resultant core-shell heteronanostructures are reported. One type of Au nanorods is prepared by seed-mediated growth, and the other is obtained by oxidation of the as-prepared Au nanorods. The (Au nanorod)@Cu2 O nanostructures produced from the as-prepared nanorods exhibit two transverse plasmon peaks, whereas those derived from the oxidized nanorods display only one transverse plasmon peak. Through electrodynamic simulations the additional transverse plasmon peak is found to originate from a discontinuous gap formed at the side of the as-prepared nanorods. The existence of the gap is verified and its formation mechanism is unraveled with additional experiments. The results will be useful for designing metal-semiconductor heteronanostructures with desired plasmonic properties and therefore also for exploring plasmon-enhanced applications in photocatalysis, solar-energy harvesting, and biotechnologies.

Enhanced H2gas sensing properties of Au@In2O3core–shell hybrid metal–semiconductor heteronanostructures

The interest in hybrid nanoparticles (NPs) arises from their combined and often synergetic properties exceeding the functionality of the individual components. Herein, a general, environmentally friendly, and facile hydrothermal approach to synthesizing the metal–semiconductor, Au@In2O3 core–shell heteronanostructures, is described. These Au@In2O3 core–shell NPs are used as chemiresistive gas sensors for the detection of hydrogen gas in air. The sensor device based on Au@In2O3 core–shell NPs showed ∼4 times greater response and is also more selective to H2 gas compared to the In2O3 NPs sensor device. The enhanced activity can be attributed to the catalytic effect of Au, and synergistic interactions between the Au and In2O3 NPs formed in the core–shell heteronanostructures in such a way that favors the efficient electron transfer at the interface. The hydrogen sensing behavior is dependent on the redox reaction between the H2 and chemisorbed oxygen species.

Synthesis and Gas Sensing Properties of Au@In2O3 Core-shell Nanoparticles

The interest in hybrid nanoparticles (NPs) arises from their combined and often synergetic properties exceeding the functionality of the individual components. Herein, a general, environmentally friendly, and facile hydrothermal approach to synthesize the metal-semiconductor, Au@In2O3 core-shell heteronanostructures is described. These Au@In2O3 core-shell NPs are used as chemiresistive gas sensors for the detection of gases such H2, CO, NO2, VOCs in air. Sensor device based on Au@In2O3 core-shell NPs showed greater response than that of In2O3 NPs sensor device. The enhanced activity can be attributed to the catalytic effect of Au, and synergistic interactions between the Au and In2O3 NPs formed into the core-shell heteronanostructures in such a way that favors the efficient electron transfer at the interface

Atom-precise polyoxometalate-ag2 s core-shell nanoparticles.

Atomically precise polyoxometalate-Ag2 S core-shell nanoparticles were generated in a top-down approach under solvothermal conditions and structurally confirmed by X-ray single-crystal diffraction as an interesting core-shell structure comprising an in situ generated Mo6 O22 (8-) polyoxometalate core and a mango-like Ag58 S38 shell. This result demonstrates the possibility to integrate polyoxometalate and Ag2 S nanoparticles into a core-shell heteronanostructure with precisely controlled atomical compositions of both core and shell.

A triple-layered, hierarchical 1D core–shell nanostructure with a plasmonic Ag octahedral core for use in solid-state dye-sensitized solar cells

A triple-layered, core–shell hetero-nanostructure was prepared with Ag octahedra, a SnO2nanotube (SNT), and a TiO2nanosheet (TNS)viaa combined process of electrospinning and solvothermal reaction.

Synthesis of TiO2@ATO core–shell nanofibers using coaxial electrospinning

Core–shell TiO2@ATO nanofibers were prepared using coaxial electrospinning technique followed by calcination. The as-prepared products were characterized by SEM, TEM, XRD and XPS. The results revealed that the nanofibers had a core of crystalline TiO2 and a shell of ATO nanoparticles. An average diameter of the nanofibers was 140nm with core diameter of 100nm and shell thickness of 20nm. This morphology leads to a high electrical activity and the versatile approach is expected to produce other core–shell heteronanostructures with high-efficiency electronic properties.

Preparation of carbon-coated NiCo2 O4 @SnO2 hetero-nanostructures and their reversible lithium storage properties.

Carbon-coated NiCo2 O4 @SnO2 core-shell hetero-nanostructures are synthesized by a facile hydrothermal process and subsequent carbon nano-coating. When evaluated as anode materials for lithium-ion batteries, the 3D hetero-nanostructures exhibit enhanced lithium storage properties due to advantageous structural features.