Shell Nanocomposites Research Articles

N, P, S co-doped hollow carbon polyhedra derived from MOF-based core–shell nanocomposites for capacitive deionization

N, P, S co-doped hollow carbon polyhedra derived from MOF-based core–shell nanocomposites were developed for capacitive deionization.

Silicone/Ag@SiO2 core-shell nanocomposite as a self-cleaning antifouling coating material.

The effects of Ag@SiO2 core–shell nanofiller dispersion and micro-nano binary structure on the self-cleaning and fouling release (FR) in the modelled silicone nano-paints were studied. An ultrahydrophobic polydimethylsiloxane/Ag@SiO2 core–shell nanocomposite was prepared as an antifouling coating material. Ag@SiO2 core–shell nanospheres with 60 nm average size and a preferential {111} growth direction were prepared via a facile solvothermal and a modified Stöber methods with a controlled shell thickness. Ag@SiO2 core–shell nanofillers were inserted in the silicone composite surface via solution casting technique. A simple hydrosilation curing mechanism was used to cure the surface coating. Different concentrations of nanofillers were incorporated in the PDMS matrix for studying the structure–property relationship. Water contact angle (WCA) and surface free energy determinations as well as atomic force microscopy and scanning electron microscope were used to investigate the surface self-cleaning properties of the nanocomposites. Mechanical and physical properties were assessed as durability parameters. A comparable study was carried out between silicone/spherical Ag@SiO2 core–shell nanocomposites and other commercial FR coatings. Selected micro-foulants were used for biological and antifouling assessments up to 28 days. Well-distributed Ag@SiO2 core–shell (0.5 wt%) exhibited the preferable self-cleaning with WCA of 156° and surface free energy of 11.15 mN m−1.

CNT@Ni@Ni–Co silicate core–shell nanocomposite: a synergistic triple-coaxial catalyst for enhancing catalytic activity and controlling side products for Li–O2 batteries

The CNT@Ni@Ni–Co silicate core–shell composites prevent the formation of side-products via structural synergistic effects, thereby enhancing its electrochemical performances for Li–O2 batteries.

The synthesis of core–shell Cu9S5@mSiO2–ICG@PEG–LA for photothermal and photodynamic therapy

A Cu9S5@mSiO2–ICG@PEG–LA core–shell nanocomposite was synthesized to integrate NIR-modulated PTT and PDT, revealing enhanced cytotoxicity to the HepG2 cell.

Poly(vinylidene fluoride)/poly(3-methylthiophene) core-shell nanocomposites with improved structural and electronic properties of the conducting polymer component.

We report significant improvements in the structure and electronic properties of a poly(3-alkylthiophene) representative, namely poly(3-methylthiophene) (P3MT), when it is synthesized in the presence of submicron electroactive poly(vinylidene fluoride) (PVDF) particles. The applied template oxidative synthesis leads to the formation of the PVDF/P3MT composite consisting of core-shell particles. The shells are constituted with a monolayer of 20-40 nm nanoparticles of the doped P3MT (P3MT-Cl) precipitated at the surface of the spherical PVDF cores. This morphology differs strongly from the hierarchical one of the neat P3MT synthesized without PVDF particles. In the latter case, 20-60 nm P3MT nanoparticles form ∼200 nm aggregates, which, in turn, are arranged in a few micrometer agglomerates. Furthermore, we demonstrate that compared to the neat polymer, doped P3MT in the shells of the composite is characterized with higher effective conjugation length, regioregularity of the molecular structure, improved intrachain packing order and lower bipolaron/polaron ratio. These features of the PVDF/P3MT composite strongly suggest applicability of this material in various electronic devices. As a proof of concept, we report on an improved sensing performance of the PVDF/P3MT-Cl composite compared with the neat P3MT-Cl in detection of several volatile organic compounds known as markers for some diseases and toxic substances. We have discovered that the maximal improvement in the sensor response magnitude corresponds to the case when the values of the analyte electronegativity and polythiophene work function are close. We associate this behavior with a higher surface dipole component of the work function of the PVDF/P3MT-Cl composite compared to that of the neat conducting polymer.

Monodisperse Cu/Cu2O@C core–shell nanocomposite supported on rGO layers as an efficient catalyst derived from a Cu-based MOF/GO structure

A novel copper/copper(i) oxide@carbon (Cu/Cu2O@C) core-shell nanocomposite monodispersed on the surface of reduced graphene oxide (defined as Cu/Cu2O@C-rGO) was synthesized using a one-step calcination of Cu-based metal organic frameworks (MOFs)/graphene oxide (GO) composite structure. The size of the resultant Cu/Cu2O@C core-shell nanoparticles (NPs) on the rGO layers were mainly distributed in range of about 90-100 nm with good dispersion, which was characterized using transmission electron microscopy. X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, nitrogen adsorption-desorption isotherms, X-ray photoelectron spectrometry and thermogravimetric analyses were also carried out to characterize the structure and composition of the Cu/Cu2O@C-rGO. The catalytic performance of the Cu/Cu2O@C-rGO composite was evaluated using a reduction reaction from 4-nitrophenol to 4-aminophenol. It was demonstrated that the Cu/Cu2O@C-rGO composite exhibited an excellent catalytic performance, which can reach a nearly 100% conversion rate in 90 s with 0.1 mg of catalyst. This catalyst also showed a good performance for the degradation of other organic dyes such as methylene blue, methyl orange and rhodamine B. Additionally, the core-shell structure exhibited good stability and reusability for the reduction reaction, which was because of its relatively better oxidation resistance than that of the bare Cu NPs. This research provided an efficient and stable non-noble metal-based catalyst derived from the MOF/GO structure.

A self-assembled silicon/phenolic resin-based carbon core-shell nanocomposite as an anode material for lithium-ion batteries.

Silicon, with advantages such as high theoretical capacity and relatively low working potential, has been regarded as promising when it is used for lithium-ion battery anodes. However, its practical application is impeded by the intrinsic low electrical conductivity and the dramatic volume change during the lithiation/delithiation process, which leads to a rapid capacity fading of the electrode. In this regard, we design silicon nanoparticles homogeneously coated with a phenolic resin-based carbon layer as a core–shell nanocomposite via a facile self-assembly method followed by carbonization. The surrounding carbon shell, confirmed by transmission electron microscopy and Raman spectroscopy, is not only beneficial to the formation of a stable solid electrolyte interface film, but the electrical conductivity of the electrode is also enhanced. A high and stable specific capacity of nearly 1000 mA h g−1 is achieved at C/3 after 200 cycles with a coulombic efficiency of >99.6%. The entire synthesis process is quite simple and easy to scale up, thus having great potential for commercial applications.

Nano Silica in Cement Hydration

In this paper, the performance of nanoscale SiO2 in cement paste has been studied. The compressive strength of hardened cement paste and the formation of Calcium Silicate Hydrate (C-S-H) in presence of nano silica (SiO2) increased. Heat of hydration increased with time with the addition of nanosilica. Core shell nanocomposite of titania and nanosilica acted as a cleaning agent and increased the compressive strength of the cement paste. It is concluded that nano silica accelerated the hydration by increasing the amount of C-S-H phase and also acting as a nucleating agent.

Preparation of MoS2-based polydopamine-modified core-shell nanocomposites with elevated adsorption performances.

New molybdenum disulfide (MoS2)-based core–shell nanocomposite materials were successfully prepared through the self-assembly of mussel-inspired chemistry. Characterization by Fourier transform infrared, thermogravimetric analysis, scanning electron microscope and transmission electron microscopy revealed that the surface of the flaked MoS2 was homogeneously coated with a thin layer of polydopamine (PDA). Dye adsorption performances of the synthesized MoS2–PDA nanocomposites were investigated at different pH values and reaction times. Compared with pure MoS2 nanosheets, the obtained core–shell nanocomposites showed elevated adsorption performances and high stability, indicating their potential applications in wastewater treatment and composite materials.

Synthesis of novel Au@Void@Nb2O5 core-shell nanocomposites with enhanced photocatalytic activity.

Nb2O5 as a semiconductor material has attracted significant attention in recent years due to its outstanding advantages. In this article, novel Au@Void@Nb2O5 core-shell nanocomposites have been fabricated through a facile sol-gel method. The construction process of this core-shell nanostructure has been presented in detail. The as-prepared core-shell nanostructure exhibits nanosphere morphology with Nb2O5 acting as the shell and Au nanoparticles acting as the core, which was proved using SEM and TEM. The noble metal Au core protected by the Nb2O5 shell promotes an interfacial charge-transfer process. The core-shell nanocomposites demonstrate excellent visible light absorption, as shown by the UV-Vis diffuse reflectance spectra. The as-prepared photocatalyst Au@Void@Nb2O5-2 calcined at 300 °C exhibits higher photocatalytic efficiency than Au@SiO2@Nb2O5-2-300 °C, Nb2O5 and P25, as evaluated by the degradation of rhodamine B (Rh B) under visible light. In the photodegradation process of the Rh B solution, holes (h+) play a more important role than hydroxyl radicals (˙OH) over the as-prepared photocatalyst, which was analyzed using active species trapping experiments and photoluminescence (PL) spectroscopy. Moreover, the photocatalyst Au@Void@Nb2O5-2 calcined at 300 °C exhibits excellent durability of its photocatalytic activity even after five successive cycles. This contribution gives a new perspective for designing and preparing novel metal-Nb2O5 nanostructure catalysts applied in environmental treatments.

Synergistic peroxidase-like activity of CeO2-coated hollow Fe3O4 nanocomposites as an enzymatic mimic for low detection limit of glucose

Abstract Fe3O4@CeO2 yolk–shell nanocomposites (NCs) were synthesized by growing CeO2 onto Fe3O4 hollow nanoparticles (NPs) as an artificial peroxidase for the purpose of elevated activity. The resultant NCs exhibited strong magnetic response with narrow size distribution and high surface area. Owing to the individual peroxidase-like catalytic activity of CeO2 onto Fe3O4 nanoparticles (NPs), Fe3O4@CeO2 NCs was investigated to achieve synergistic catalytic activity. As a result, the as-prepared Fe3O4@CeO2 NCs exhibited impressive peroxidase-like catalysis activity for 3, 3′, 5, 5′-tetramethylbenzidine (TMB). Moreover, comparing with natural enzymes, hollow Fe3O4 NPs and CeO2 NPs, the Fe3O4@CeO2 NCs displayed a lower Michaelis constant (Km) value or stronger affinity to H2O2 and TMB. A limit of detection of 8.5 µmol/L for H2O2 and 21 µmol/L for glucose was attained with acceptable stability and reproducibility. The activation mechanism was also studies using competitive radical tests and Electron spin resonance (ESR) analysis.

A pH‐Sensitive Composite with Controlled Multistage Drug Release for Synergetic Photothermal Therapy and Chemotherapy

Multifunctional core–shell nanocomposites are excellent platforms for effective drug delivery, and controlled release is attracting increasing attention from researchers owing to its advantages in cancer therapy. Here, a new nanocomposite containing nitrogen‐doped carbon dots (N‐CDs) embedded in ferromagnetic Fe3O4 cores and a pH‐sensitive shell constituted by hydroxyapatite (HA) with loaded 5‐fluorouracil (5‐FU) was successfully synthesized. The nanocomposite can be used for near‐infrared laser‐induced photothermal cancer therapy and synergetic chemotherapy. The pH‐sensitive HA shell exhibits a high drug‐loading capability and achieves a pH‐controlled and multistage drug release. As a result, this multifunctional core–shell N‐CDs@Fe3O4@HA‐5FU nanocomposite is an excellent and promising candidate with significant potential for targeted and synergetic cancer treatment.

Fabrication of hierarchical MXene-based AuNPs-containing core–shell nanocomposites for high efficient catalysts

MXene is a new type of layered two-dimensional transition metal carbide materials differing from graphene, demonstrating intriguing chemical/physical properties. Here the chemical modification of MXene and next fabrication of core–shell MXene–COOH@(PEI/PAA)n composites have been investigated. The obtained MXene-based composites were treated with gold nanoparticles to form MXene–COOH@(PEI/PAA)n@AuNPs nanocomposites, and their catalytic properties for nitro-compounds were studied. The prepared nanocomposites demonstrated good catalytic activity and reproducibility, showing potential applications in composite catalysts and environmental fields.

Laser ablation of Au–CuO core–shell nanocomposite in water for optoelectronic devices

Core–shell gold–copper oxide Au–CuO nanocomposites were synthesized using laser ablation of CuO target in colloidal solution of Au nanoparticles (NPs). The effect of laser fluence on the structural, morphological, electrical, and optical properties of Au–CuO nanocomposites was investigated using x-ray diffraction (XRD), atomic force microscope (AFM), scanning electron microscope (SEM), transmission electron microscope (TEM), photoluminescence (PL), Fourier transformed infrared spectroscopy (FTIR), Hall measurement, and UV–vis spectroscopy. X-ray diffraction results confirm the formation of polycrystalline Au–CuO NPs with monoclinic structure. The optical energy gap for CuO was 4 eV and for the Au–CuO core–shell nanocomposites was found to be in the range of 3.4–3.7 eV. SEM and TEM investigations revealed that the structure and morphology of Au–CuO core–shell nanocomposites were strongly depending on the laser fluence. A formation of Au–CuO nanospheres and platelets structures was observed. The photoluminescence data showed an emission of broad visible peaks between 407 and 420 nm. The effect of laser fluence on the dark and illuminated I–V characteristics of Au–CuO/n-Si heterojunction photodetectors was investigated and analyzed. The experimental data demonstrated that the photodetector prepared at optimum laser fluence exhibited photosensitivity of 0.6 AW−1 at 800 nm.

Design and Application of Magnetic Photocatalysts for Water Treatment. The Effect of Particle Charge on Surface Functionality

Core-interlayer-shell Fe3O4/SiO2/TiO2, CoFe2O4/SiO2/TiO2 and BaFe12O19/SiO2/TiO2 magnetic photocatalysts were obtained. A water-in-oil microemulsion system with suitable surfactants was used for functionalization of the magnetic core with silica interlayer and TiO2-based photocatalyst. Uncoated and coated particles were characterized by electrophoretic measurements, X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), specific surface area (BET) measurements, diffuse reflectance spectroscopy (DRS) and vibrating sample magnetometer (VSM) analysis. The pH of the solution and corresponding zeta potential was found to be essential for appropriate formation of ferrite core/silica interlayer/TiO2 shell nanocomposite, since the electrical charge controls interactions during functionalization of the magnetic core particles. Thus, the development of multilayer structure in the isoelectric point (IEP) region enhanced adhesion of ferrite, silica and titania particles. The obtained Fe3O4/SiO2/TiO2, CoFe2O4/SiO2/TiO2 and BaFe12O19/SiO2/TiO2 nanocomposites revealed superparamagnetic behavior. The decomposition rate of phenol and carbamazepine allowed to estimate their photocatalytic activity. Progress of photocatalytic mineralization of organic compounds was evaluated by total organic carbon (TOC) measurements. Photocatalytic activity measured in four subsequent cycles showed good reusability as no loss of efficiency of phenol degradation was observed.

Hollow Copper Sulfide Nanosphere-Doxorubicin/Graphene Oxide Core-Shell Nanocomposite for Photothermo-chemotherapy.

A novel core-shell nanostructure, hollow copper sulfide nanosphere-doxorubicin (DOX)/graphene oxide (GO) (CuS-DOX/GO), is constructed for the purpose of controlled drug delivery and improved photothermo-chemotherapeutic effect. The CuS-DOX/GO nanocomposite is configured by employing dual photothermal agents, where the core, hollow CuS nanoparticle, acts as delivery-carrier for doxorubicin, and the shell, PEGylated GO nanosheet, prohibits leakage of the drug. DOX can be efficiently loaded onto the hollow CuS nanoparticles, and its subsequent release from CuS-DOX/GO nanocomposite is triggered in a pH- and near-infrared light-dependent manner. Moreover, integration of the two photothermal agents significantly improves the photothermal performance of this system. Ultimately, the combination of phototherapy and chemotherapy based on this system results in a much higher HeLa cell killing efficacy with respect to that for a single chemotherapy mode, as demonstrated by in vitro cytotoxicity tests.

Synthesis and evaluation of NiO@MCM-41 core–shell nanocomposite in the CO2 reforming of methane

In this paper, the synthesis of core shell structured NiO@MCM-41 nanocomposite via vesicles as soft template is reported for the first time. Its catalytic performance was investigated in the CO2 reforming of methane (CRM) conversion. Stable vesicles first formed with CTAB/SDBS surfactant ratio of 1:2. Nickle nitrate was added to the vesicle mixture followed by addition of the aqueous solution of vesicle containing Ni cations inside to the MCM-41 gel. After high-temperature calcination, NiO@MCM-41 nanocomposite were obtained. The structural symmetry and the surface morphology were characterized by transmission electron microscope (TEM), low angle X-Ray Diffraction (XRD) and N2 adsorption/desorption analysis. TEM image confirmed core–shell structure and the hexagonally ordered structure of shell of MCM-41 silica. The results indicated that the average diameter of synthesized core–shell NiO@MCM-41 particles is 70–80 nm and the most of them are of spherical shape. The result of small angle XRD and N2 isotherm adsorption/desorption analyses indicated successfull formation of mesoporous shell. Hydrogen consumption by the catalyst mainly at 700 °C in TPR profile showed the strong interaction of the most of Nickel content with the support. CRM conversion on the prepared catalyst after 245 min of reaction led to H2 conversion at 42%, CO2 conversion at 48% with H2/CO yield ratio of 0.8.

Synthesis, characterisation, cellular uptake and cytotoxicity of functionalised magnetic ruthenium (II) polypyridine complex core-shell nanocomposite

The development of multifunctional nanoparticles comprising of a magnetic core in conjunction with appropriate molecules with capabilities to impart functionalities like luminescent, specific binding sites to facilitate attachment of moieties. This has attracted increasing attention and enables identification of promising candidates using for applications such as diagnostics and cure through early detection and localized delivery. Many studies have been performed on the synthesis and cellular interactions of core–shell nanoparticles, in which a functional inorganic core is coated with a biocompatible polymer layer that should reduce nonspecific uptake and cytotoxicity Here we report the synthesis and characterisation of multifunctional core-shell magnetic, luminescent nanocomposite (Fe3O4@SiO2@[Ru(Phen)3]2+@SiO2@NH2). Fe3O4 as core and a luminescent ruthenium (II) complex encapsulated with silica shell, and then it is functionalized by an amine group by APTMS. The magnetic, luminescent, and biological activity of this multifunctional nanocomposite have also been studied to prove the nanocomposite is biocompatible, cellular uptake. The synthesized nanocomposite was completely characterized by X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), and emission spectroscopy. MTT assay and cellular uptake by flow cytometry results proved that magnetic ruthenium (II) polypyridine complex – core shell nanocomposite has biocompatibility, minimum cytotoxicity and internalized inside B16F10 cells and confirms the potential biomedical applications.

An Electroactive and Regenerable Fe3O4@Polypyrrole Nanocomposite: Fabrication and Its Defluorination in an Electromagnetic Coupling System

An electrochemically regenerable Fe3O4@polypyrrole (PPy) core–shell nanocomposite with superparamagnetism for selective fluoride ion removal from wastewater is fabricated. The rapid fluoride ion uptake kinetics is realized in a batch experiment due to the good affinity of PPy toward fluoride ions. It is found that the pseudo-second-order model can well describe the adsorption kinetics and the equilibrium data fits well with the Freundlich isotherm model. The spontaneity and exothermic nature of the fluoride ion adsorption are confirmed based on thermodynamic parameter analysis. In an electromagnetic coupling system, the nanocomposites exhibit a high regeneration efficiency around 95% in each cycle and only a slight drop in the capacity retention rate of fluoride ion adsorption even after 20 adsorption–regeneration cycles. This intelligently magnetic nanocomposite should be a promising alternative material for fluoride ion removal from wastewater.

Laser pyrolysis synthesis of Sn–Fe–N@polycarbosilazane nanocomposites, characterization and evaluation as energy storage materials

We report the single-step synthesis of novel tin-based core–carbosilazane shell nano-composites using laser pyrolysis technique. Controlled NH3 flows were used to entrain the vapors of volatile precursors: Sn(CH3)4 (TMT) and Fe(CO)5 injected through center for the core and [Si(CH3)3]2NH (HMDS) through the annular nozzle for the shell. Both NH3 and HMDS plays also the role of absorbers of the IR laser radiation. The obtained nanoparticles shown polydispersity with sizes from 5 up to around 120 nm, having spheroidal crystalline core—disordered shell morphology as confirmed by transmission electron microscopy images, where also short amorphous nanofibers were observed. The dominant crystalline phase β-Sn (having mean crystallite size between 22 and 29 nm) and minor tin-iron intermetallic and nitride phases were identified by X-ray diffraction. Infrared spectra show the presence of Si–N and Si–C bonds, pointing to a carbosilazane composition of the shells, accompanied by Si–O bonds due to partial oxidation after air exposure. Three different samples were obtained by keeping constant the Sn and Fe precursors flows and diminishing the HDMS flow, together with the corresponding NH3 flows. Preliminary tests of these materials as anodes for Li-ion battery showed an initial discharge capacity near 800 mAg/h which decreased to 300 mAh/g after 20 cycles for the sample having the highest Sn content.