Synthesized Core Shell Nanoparticles Research Articles

Sub-3 nm Pt@Ru toward Outstanding Hydrogen Oxidation Reaction Performance in Alkaline Media.

Anion-exchange membrane fuel cells (AEMFCs) are promising alternative hydrogen conversion devices. However, the sluggish kinetics of the hydrogen oxidation reaction in alkaline media hinders further development of AEMFCs. As a synthesis method commonly used to prepare disordered PtRu alloys, the impregnation process is ingeniously designed herein to synthesize sub-3 nm Pt@Ru core-shell nanoparticles by sequentially reducing Pt and Ru at different annealing temperatures. This method avoids complex procedures and synthesis conditions for organic synthesis systems, and the atomic structure evolution of the synthesized core-shell nanoparticles can be tracked. The synthesized Pt@Ru electrocatalyst shows an ultrasmall average size of ∼2.5 nm and thereby a large electrochemical surface area (ECSA) of 166.66 m2 gPt+Ru-1. Exchange current densities (j0) normalized to the mass (Pt + Ru) and ECSA of this electrocatalyst are 8.0 and 5.8 times as high as those of commercial Pt/C, respectively. To the best of our knowledge, the achieved mass-normalized j0 measured by rotating disk electrodes is the highest reported so far. The membrane electrode assembly test of the Pt@Ru electrocatalyst shows a peak power density of 1.78 W cm-2 (0.152 mgPt+Ru cmanode-2), which is higher than that of commercial PtRu/C (1.62 W cm-2, 0.211 mgPt+Ru cmanode-2). The improvement of the intrinsic activity can be attributed to the electron transfer from the Ru shell to the Pt core, and the ultrafine particles further enhance the mass activity. This work reveals the feasibility of using simple impregnation to synthesize fine core-shell nanocatalysts and the importance of investigating the atomic structure of PtRu nanoparticles and other disordered alloys.

Suppression of Cation Intermixing Highly Boosts the Performance of Core-Shell Lanthanide Upconversion Nanoparticles.

Lanthanide upconversion nanoparticles (UCNPs) have been extensively explored as biomarkers, energy transducers, and information carriers in wide-ranging applications in areas from healthcare and energy to information technology. In promoting the brightness and enriching the functionalities of UCNPs, core-shell structural engineering has been well-established as an important approach. Despite its importance, a strong limiting issue has been identified, namely, cation intermixing in the interfacial region of the synthesized core-shell nanoparticles. Currently, there still exists confusion regarding this destructive phenomenon and there is a lack of facile means to reach a delicate control of it. By means of a new set of experiments, we identify and provide in this work a comprehensive picture for the major physical mechanism of cation intermixing occurring in synthesis of core-shell UCNPs, i.e., partial or substantial core nanoparticle dissolution followed by epitaxial growth of the outer layer and ripening of the entire particle. Based on this picture, we provide an easy but effective approach to tackle this issue that enables us to produce UCNPs with highly boosted optical properties.

α-Fe2 O3 @Ag and Fe3 O4 @Ag Core-Shell Nanoparticles: Green Synthesis, Magnetic Properties and Cytotoxic Performance.

This work provides the synthetic route for the arrangement of Fe3 O4 @Ag and α-Fe2 O3 @Ag core-shell nanoparticles (NPs) with cytotoxic capabilities. The production of Fe3 O4 @Ag and α-Fe2 O3 @Ag core-shell NPs was facilitated utilizing S. persica bark extracts. The results of Powder X-ray Diffraction (PXRD), Ultraviolet-visible (UV-Vis) spectroscopy, Vibrating Sample Magnetometry (VSM), Energy Dispersive X-ray (EDX) analysis, Field Emission Scanning Electron Microscopy (FESEM), and Transmission Electron Microscopy (TEM) supported the green synthesis and characterization of Fe3 O4 @Ag and α-Fe2 O3 @Ag NPs. The particle size was measured by the TEM analysis to be about 30 and 50 nm, respectively; while the results of FESEM showed that α-Fe2 O3 @Ag and Fe3 O4 @Ag particles contained multifaceted particles with a size of 50-60 nm and 20-25 nm, respectively. The outcomes of VSM were indicative of a saturation magnetization of 37 and 0.18 emu/g at room temperature, respectively. The potential cytotoxicity of the synthesized core-shell nanoparticles towards breast cancer (MCF-7) and human umbilical vein endothelial (HUVEC) cells was evaluated by an MTT assay. α-Fe2 O3 @Ag NPs were able to destroy 100 % of MCF-7 cell at doses above 80 μg/mL, and it was confirmed that Fe3 O4 @Ag NPs at a volume of 160 μg/mL can destroy 90 % of MCF-7 cells. Thus, the applicability of the prepared nanoparticles of these nanoparticles in biological and medical fields has been demonstrated.

Targeted dielectric coating of silver nanoparticles with silica to manipulate optical properties for metasurface applications

An epsilon-negative metamaterial (ENM) containing core@shell nanoparticles (NPs) was designed, where silver (Ag) NPs served as core and silica (SiO2) was used as spacer shell. AgNPs were synthesized in large scale, using microwave-assisted polyol method, in three average particle sizes, as 30, 54, and 61 nm, with a narrow particle size distribution. Optical absorption of Ag NPs was investigated using UV–Vis spectroscopy. Their optical behavior was also theoretically predicted for different thicknesses of the SiO2 shell immersed in media of different refractive indices using the Clausius - Mossotti equation. Based on the results, optimal outputs were obtained with a SiO2 shell of 10 nm in thickness encompassing 54 nm Ag NPs based on the analytical model and numerical simulations here developed for core-shell structures. Then 10 nm SiO2 shell was grown on 54 nm Ag NPs by sol-gel synthesis. The NPs were then characterized by UV–Vis, TEM, SEM, EDX, DLS, and zeta potential analyses. The synthesized core-shell NPs can be used to establish epsilon-negative properties in polymer layers within visible range of wavelengths.

New Core-Shell Nanostructures for FRET Studies: Synthesis, Characterization, and Quantitative Analysis.

This work describes the synthesis and characterization of new core-shell material designed for Förster resonance energy transfer (FRET) studies. Synthesis, structural and optical properties of core-shell nanostructures with a large number of two kinds of fluorophores bound to the shell are presented. As fluorophores, strongly fluorescent rhodamine 101 and rhodamine 110 chloride were selected. The dyes exhibit significant spectral overlap between acceptor absorption and donor emission spectra, which enables effective FRET. Core-shell nanoparticles strongly differing in the ratio of donors to acceptor numbers were prepared. This leads to two different interesting cases: typical single-step FRET or multistep energy migration preceding FRET. The single-step FRET model that was designed and presented by some of us recently for core-shell nanoparticles is herein experimentally verified. Very good agreement between the analytical expression for donor fluorescence intensity decay and experimental data was obtained, which confirmed the correctness of the model. Multistep energy migration between donors preceding the final transfer to the acceptor can also be successfully described. In this case, however, experimental data are compared with the results of Monte Carlo simulations, as there is no respective analytical expression. Excellent agreement in this more general case evidences the usefulness of this numerical method in the design and prediction of the properties of the synthesized core-shell nanoparticles labelled with multiple and chemically different fluorophores.

Tuning visible emission of core-shell nanostructure by exchange the inner and outer layer

Herein, we report that synthesis of ZnS/Bi2S3 and Bi2S3/ZnS core-shell nanostructure prepared by ‘one-pot’ chemical method. We have studied the effect of structural, morphological, optical and thermal properties by exchanging the inner and outer layer of core-shell nanoparticles. The samples were studied using various characterization techniques such as XRD, TEM, FTIR, UV–Vis, Photoluminescence and TG-DTA. The XRD and TEM results demonstrated that the synthesized core-shell nanoparticles were in cubic (ZnS)-orthorhombic (Bi2S3) mixed crystal structures with a diameter of 18.6 nm and 16.3 nm with extremely monodispersing. The obtained result provides a new and simple route for synthesis of sulfide-based core-shell nanoparticles with high crystal quality.

Synthesis of core-shell structure based on silica nanoparticles and methacrylic acid via RAFT method: An efficient pH-sensitive hydrogel for prolonging doxorubicin release

In recent years, much attention has been received on stimuli-responsive nanocarriers in nanomedicine. In this work, a pH-responsive core-shell system based on silica nanoparticles (SNPs) as core and methacrylic acid hydrogels as shell were synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. Methacrylic acid hydrogel through bulk and RAFT polymerization was developed as a model to compare with core-shell hydrogel. The synthesized nanocarriers were characterized by TGA, FT-IR, SEM, TEM, and DLS techniques. To investigate the synthesized core-shell nanoparticles as anticancer nanocarriers, Doxorubicin (DOX) was used as a model drug. In-vitro drug release manner at physiological barriers (pH 7.4) and cancer cell conditions (pH 4.8) illustrates a pH-controlled release for the nanocarriers over 15 days. The study of drug release kinetics reveals that the release mechanism of the carriers followed by the Gompertz model. In addition, the DOX-loaded nanocarriers have notable cytotoxicity against human breast MCF-7 cells with 0.7866 μM IC50 for core-shell nanocarrier. The obtained results showed that the prepared pH-responsive core-shell hydrogel has a high potential to be employed as a sustained pH-sensitive drug release system.

Synthesis of Fe3O4@MIL-101(Fe) for a Novel Electrochemistry Detection of Citric Acid

Introduction Urolithiasis is one of the most common diseases in the urinary system with very high incidence worldwide. In recent studies, citric acid (CA) has been considered as a biomarker of urolithiasis due to its vital suppression role in urinary stone formation. The detection of CA in urine is of great significance for early screening and prognostic monitoring of urolithiasis. However, most analytical methods for detecting CA are complicated and require expensive equipment.In the present study[1, 2], MIL-101(Fe) and Fe3O4 were used for electrochemical detection of CA, based on the reaction of Fe(Ⅲ) and CA. Following these ideas, the electrodes modified with Fe3O4@MIL-101(Fe) nanoparticles were fabricated and investigated for whether they were able to detect CA and improve the sensitivity. Method Synthesis of Fe3O4@MIL-101(Fe) nanoparticles(Figure1. A): The Fe3O4@MIL-101(Fe) core-shell nanoparticles were synthesized according to previous literatures[3, 4]. Specifically, 3.6 g NaAC and 0.87 g FeCl3 were dissolved in 75 mL ethylene glycol under ultrasound for 30 minutes. The mixture was transferred to a Teflon-lined autoclave chamber and heated at 200 °C for 16 h, then naturally cooled to room temperature. The obtained magnetic nanoparticles were collected with a magnet and washed with ethanol for three times. 350 mg above nanoparticles was dissolved to 75mL ethanol with 0.58mM Mercapto acetic acid (MAA), and gently stirred for 24h under nitrogen protection. The steps of self-assembly cycle were as follows. Firstly, 100 mg Fe3O4-MAA was dispersed in 10mM FeCl3, shaked for 1 minute and left for 15 minutes, then washed with ethanol for three times. Next, the nanoparticles was re-dispersed in 10 mM benzene-1,3,5-tricarboxylic acid, kept for 30 min at 70 °C with stripping, and then washed with ethanol for three times. After repeating this cycle 31 times, the synthesized core-shell nanoparticles were dried at 75 °C. Fabrication of the Fe3O4@MIL-101(Fe) /GCE: The GCE working electrode was polished with 1.0, 0.3, and 0.05 μm Al2O3 substance and sonicated with an ethyl alcohol and water solution for 5 min respectively then dried under a N2 stream. For the modification, the synthesized Fe3O4@MIL-101(Fe) core-shell nanoparticles was dissolved in ultrapure water and the final concentration was 1.0 mg/mL. After sonicating for 1 hour, 7 µL of the suspension was dripped onto the surface of the GCE and dried at room temperature. Detection of CA: Electrochemical analyses were carried out using differential pulse voltammetry (DPV) measurements in 0.01M KCl solution with different concentration of CA at pH 7.0. All experiments were performed at room temperature with a three-electrode system: Ag/AgCl (3 M KCl) electrode and platinum wire were used as a reference electrode and counter electrode, respectively, and applying in a potential range of 0 to 0.60 V, with an amplitude of 0.025 V and pulse period of 0.5 s. Results and Conclusions Characterization of Fe3O4@MIL-101(Fe): TEM images of as-prepared nanoparticles is shown in Figure 1. B. The Fe3O4@MIL-101(Fe) had spherical morphology and the core–shell structures which indicated the formation of MIL-101(Fe) layer on the Fe3O4 nanoparticles.. The dark core was the Fe3O4 with a diameter of about 348 nm, and the relatively bright outer layer was the MIL-101(Fe) with the thickness of 246 nm. The detection of CA: The DPVs of Fe3O4@MIL-101(Fe) /GCE in the 0.1M KCl with or without 100 mg/L CA are shown in Figure 1. C. In the presence of CA, a current peak was obtained in 0.324V. This could be explained due to the reaction of Fe3+ ions in Fe3O4@MIL-101(Fe) with CA. The performance of the Fe3O4@MIL-101(Fe) /GCE in different concentrations of CA solutions were monitored by DPV, and the corresponding ΔCurrent( ) are shown in Figure 1.D. The resulting calibration is presented in the Figure 1. E, which was linear over the concentration range of 40 to 100 mg/L and 100-500 mg/L CA, with the linear regression equations of Y = 0.0004*X +0.004 (R2 = 0.9956) and Y = 0.00016*X + 0.03773 (R2 = 0.9766), respectively. Based on three times the background noise, the modified electrode provided a limit of detection of 31 mg/L. References Valizadeh, H., J. Tashkhourian, and A.J.M.A. Abbaspour, A carbon paste electrode modified with a metal-organic framework of type MIL-101 (Fe) for voltammetric determination of citric acid. 2019. 186(7): p. 455. Guivar, J.A.R., et al., Preparation and characterization of cetyltrimethylammonium bromide (CTAB)-stabilized Fe3O4 nanoparticles for electrochemistry detection of citric acid. 2015. 755: p. 158-166. Chen, Y., et al., Facile preparation of core–shell magnetic metal–organic framework nanoparticles for the selective capture of phosphopeptides. 2015. 7(30): p. 16338-16347. Salman, F., A. Zengin, and H.Ç.J.I. Kazici, Synthesis and characterization of Fe 3 O 4-supported metal–organic framework MIL-101 (Fe) for a highly selective and sensitive hydrogen peroxide electrochemical sensor. 2020. 26(10): p. 5221-5232. Figure 1

Synthesis, Characterization and Photocatalytic study of FeCr2 O4 @ZnO@MgO Core-Shell Nanoparticle

In the present work, the sol-gel derived powders of the chemical form FeCr2O4@ZnO@MgO Core-shell, has been synthesized and used as a photocatalyst. The synthesized core-shell nanoparticles characterized by various analytical techniques including FTIR, XRD, SEM-EDAX, and HR-TEM-SEAD. The successful performance of synthesized core-shell photocatalyst FeCr2O4@ZnO@MgO has been also demonstrated for the complete mineralization of Orange G dye. The effect of various operational parameters used in dye degradation such as concentration of dye, light intensity, amount of photocatalyst, effect of light and effect of electrolyte has been studied on the rate of reaction. TEM analysis clearly shows two layers of ZnO and MgO on FeCr2O4. The highest degradation rate was found with concentration of Orange G dye 10 ppm, 0.8 g of FeCr2O4@ZnO@MgO and time 50 min. The recyclability of the photocatalyst, FeCr2O4@ZnO@MgO was performed up to four runs. The degradation mechanism has been established by using LC-MS analysis and it was used to track the numerous intermediate products formed during the course of Orange G dye degradation.

Smartphone-based Fluoride-specific Sensor for Rapid and Affordable Colorimetric Detection and Precise Quantification at Sub-ppm Levels for Field Applications

Higher levels of fluoride (F–) in groundwater constitute a severe problem that affects more than 200 million people spread over 25 countries. It is essential not only to detect but also to accurately quantify aqueous F– to ensure safety. The need of the hour is to develop smart water quality testing systems that would be effective in location-based real-time water quality data collection, devoid of professional expertise for handling. We report a cheap, handheld, portable mobile device for colorimetric detection and rapid estimation of F– in water by the application of the synthesized core–shell nanoparticles (near-cubic ceria@zirconia nanocages) and a chemoresponsive dye (xylenol orange). The nanomaterial has been characterized thoroughly, and the mechanism of sensing has been studied in detail. The sensor system is highly selective toward F– and shows unprecedented sensitivity in the range of 0.1–5 ppm of F–, in field water samples, which is the transition regime, where remedial measures may be needed. It addresses multiple issues expressed by indicator-based metal complexes used to determine F– previously. Consistency in the performance of the sensing material has been tested with synthetic F– standards, water samples from F– affected regions, and dental care products like toothpastes and mouthwash using a smartphone attachment and by the naked eye. The sensor performs better than what was reported by prior works on aqueous F– sensing.

Optimization of Fe@Cu Core–Shell Nanoparticle Synthesis, Characterization, and Application in Dye Removal and Wastewater Treatment

Green synthesis of core–shell nanoparticles is gaining importance nowadays as it is viewed as being environmental friendly and cost effective. The present study aimed to synthesize iron@copper core–shell nanoparticles using a polysaccharide-based bioflocculant from Alcalegenis faecalis and to evaluate its efficiency in dye removal and river water and domestic wastewater treatment. The synthesized samples were characterized by Fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, transmission electron microscopy, and UV-Vis spectroscopy analysis. To optimize the best concentration for core–shell formation, different ratios of iron to copper were prepared. Sample 1 (S1) contained 1:3 iron to copper (Fe 25%–Cu 75%), sample 2 (S2) contained 1:1 iron to copper (Fe 50%–Cu 50%), and the third sample (S3) contained 3:1 iron to copper (Fe 75%–Cu 25%). The flocculation activity (FA) was above 98% at 0.2 mg/mL for all the samples and the samples flocculated well under acidic, alkaline, and neutral pH conditions. Sample 3 was shown to be thermostable, with flocculation activity above 90%, and samples 2 and 1 were also thermostable, but the flocculation decreased to 87 at 100 °C. All three samples revealed some remarkable properties for staining dye removal as the removal efficiency was above 89% for all dyes tested. The synthesized core–shell nanoparticles could remove nutrients such as total nitrogen and phosphate in both domestic wastewater and Mzingazi river water. Furthermore, high removal efficiency for chemical oxygen demand (COD) and biological oxygen demand (BOD) was also observed.

Synthesis of Iron Oxide@Pt Core-Shell Nanoparticles for Reductive Conversion of Cr(VI) to Cr(III) and Antibacterial Studies.

Herein, we report the facile synthesis of Iron oxide@Pt core-shell nanoparticles (NPs) by facile two step synthesis process. The first step follows the growth of iron oxide nanoparticle by thermal decomposition process while the second step deals with the formation of iron oxide@Pt core-shell nanoparticles by the chemical reduction method. The synthesized core-shell nanoparticles were characterized by several techniques and used for the catalytic reductive translation of Cr(VI) to Cr(III) in the presence of formic acid by a UV-vis spectrophotometer. The UV photo-spectrometer analysis confirmed the conversion efficiency from 12% to as high as 98.8% at the end of 30 minutes. Thus, the presence of Iron oxide @Pt core-shell nanoparticles (NPs) can be effectively used as a catalyst for the reducion of Cr(VI) to Cr(III) ions. Additionally, antibacterial studies were performed for the prepared core-shell nanoparticles against two bacterial strains, i.e., gram (+ve) Staphylococcus Aureus (S. Aureus) and gram (-ve) Escherichia Coli (E. Coli).

Intense Pulsed Light Sintered Core-Shell Nanoparticles for Organic Photovoltaic Devices

A fast and low-cost fabrication process using intense pulsed light sintering of metal nanoparticles was studied. Silver, copper, and four different copper-silver core-shell alloy nanoparticles were synthesized. The composition and resistivity of the sintered metal electrodes were studied. The resistivity of the silver electrode formed through nanoparticle sintering was comparable to that of a conventional solution-processed silver electrode. The performance of the device prepared using the copper nanoparticles only was low due to the oxidation of copper in the air. The current density-voltage (J-V) characteristics of the devices fabricated using the synthesized core-shell nanoparticles revealed that the alloy ratio up to approximately 2 did neither affect the performances nor the lifetime of the devices. As the content of copper increased, the device performance decreased due to the oxidation of copper. Usage of the sintered metal alloy electrodes resulted in the reduction of cost by 33% compared with the conventional silver electrode.

Ultrafast electrochemical deposition of core shell metal nanoparticles on TiO2 nanotubes for electrocatalytic applications

In this work, we report a rapid and reliable electrochemical synthetic method for decoration of core–shell nanoparticles of Pt and Au over titania nanotubes (TNTs). The decoration was achieved in an ultrafast manner within a span of 60 s without using any reducing agents or any use of further thermal of chemical treatments. The successful formation of double shell nanoparticles such as AuPt@Pt-TNT, PtAu@Au-TNT and single shell nanoparticles such as Pt@Au-TNT was characterized by using transmission electron microscopy (TEM), x-ray photo electron spectroscopy (XPS), energy dispersive x-ray spectroscopy (EDS) and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) techniques. The synthesized core–shell nanoparticles showed good electrocatalytic activity towards aqueous and non-aqueous ORR applications.

Self-healing and corrosion protection performance of organic polysulfide@urea-formaldehyde resin core-shell nanoparticles in epoxy/PANI/ZnO nanocomposite coatings on anodized aluminum alloy

Coatings of epoxy resin blended with polyaniline (PANI)/ZnO nanocomposites and core-shell nanoparticles of organic polysulfide@urea-formaldehyde resin as self-healing agents have been prepared. The corrosion inhibition and self-healing performance of the scratched coatings on the anodized aluminum alloy (2024-T3) substrates in 3.5% brine at 65 °C were investigated. PANI/ZnO nanocomposite (1.3% ZnO) have been successfully prepared by in-situ emulsion polymerization of aniline in the presence of ZnO nanoparticles. The core-shell nanoparticles of organic polysulfide@urea-formaldehyde resin (60–80 nm) was synthesized via two microemulsions method. The materials were characterized by Fourier transform infrared (FT-IR) spectroscopy, dynamic light scattering (DLS), scanning electron microscopy (SEM) and thermal gravimetric analysis (TGA) techniques. The morphology of the coatings was studied by atomic force microscopy (AFM). Corrosion behavior of the coatings were investigated by electrochemical impedance spectroscopy (EIS). Finally, epoxy/PANI/ZnO coatings containing relative amounts of 0, 5, 7.5 and 10 wt% of the synthesized core-shell nanoparticles were fabricated on the anodized aluminum alloy and their electrochemical and self-healing behavior were studied. The coating with 7.5% core-shell have resulted to a much more superior corrosion protection than other samples, and also a significant self-healing response against the cracks exerted on the coatings.

Synthesis of pH‐responsive magnetic yolk–shell nanoparticles: A comparison between conventional etching and new deswelling approaches

Iron oxide (Fe3O4) magnetic nanoparticles as movable cores were used to synthesize yolk–shell nanoparticles with pH‐responsive shell composed of ethylene glycol dimethacrylate (EGDMA)‐crosslinked poly(acrylic acid) (PAA) via two different routes. In the first more common route, Fe3O4 nanoparticles were coated with silica layer via the Stöber process to yield Fe3O4@SiO2 core–shell nanoparticles, subsequently used as seeds in the distillation precipitation copolymerization of AA and EGDMA to yield Fe3O4@SiO2@P(AA‐EGDMA). The silica layer was selectively removed through alkali etching to yield Fe3O4@air@P(AA‐EGDMA). In the second route, Fe3O4 nanoparticles without any stabilization were used as seeds in the distillation precipitation copolymerization of AA and EGDMA to yield Fe3O4@P(AA‐EGDMA) core–shell nanoparticles. The nanoparticles were subsequently dispersed in acidic medium of pH = 2. Yolk–shell Fe3O4@air@P(AA‐EGDMA) nanoparticles were formed through deswelling of crosslinked PAA because of protonation of carboxyl groups at low pH values. Various techniques were utilized to investigate the characteristics of the synthesized core–shell nanoparticles. Formation of yolk–shell nanostructure was observed for both synthesis routes, namely etching of silica layer and deswelling approaches, from vibrating sample magnetometry and transmission electron microscopy results. Both types of nanoparticles showed pH‐responsive behaviour, i.e. decrease in absorption with increase in pH, as examined using UV–visible spectroscopy.

Phyto and hydrothermal synthesis of Fe3O4@ZnO core-shell nanoparticles using Azadirachta indica and its cytotoxicity studies

Core-shell nanoparticles are highly functional material having potential applications in biomedical and pharmaceuticals due to its excellent properties like increased thermal and chemical stability, dispersibility, less cytotoxicity and biocompatibility. Fe3O4@ZnO core-shell nanoparticles were synthesized with different molar ratios of core to shell by the two-step synthesis of phyto and hydrothermal synthesis using Azadirachta indica (neem) leaves. Synthesis of nanoparticles using plants is mostly preferable nowadays owing to its eco-friendly, simple, cost-effective and biocompatible nature. The synthesized core-shell nanoparticles were identified and nanostructural properties were studied by X-ray diffractometer (XRD), Fourier Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscope (SEM) techniques with EDX and Transmission Electron Microscope (TEM). Thermal stability of nanoparticles was obtained from Thermo Gravimetric Analyzer (TGA). The toxicity of the Fe3O4@ZnO core-shell nanoparticles against Vero cells was investigated using MTT assay shows that the cell viability decreases with the higher concentration of nanoparticles.

A comparative study of electrocatalytic performance of the M@Pt (M = Fe3O4, Co and Ni) nanoparticles for direct ethanol fuel cells

In this study, we have successfully synthesized the M@Pt (M = Fe3O4, Co and Ni) nanoparticles catalysts through the sodium borohydride reduction method for a comparative studies of their electrocatalytic performance towards ethanol oxidation in acidic media. After the structure, surface morphology and chemical composition characterization of the synthesized core–shell nanoparticles, their electrocatalytic activities towards oxidation of ethanol in acidic media were studied in detail. We investigated the effect of the core element (Fe3O4, Co and Ni) on the electrochemical behaviour as well as the enhancement of the electrocatalytic activity for ethanol oxidation reaction. Overall, the obtained results show that the all of these electrocatalysts exhibited an enhanced activity than Pt-alone nanoparticles towards ethanol oxidation reaction. On the other hand, the comparative studies of their electrocatalytic performance show that the Ni@Pt nanoparticles present the best performance with the maximum electrocatalytic activity and stability.

Synthesis, structural, optical and morphological properties of CdSe:Zn/CdS core–shell nanoparticles

CdSe:Zn/CdS core–shell nanoparticles have been synthesized through the chemical precipitation method. The structural, optical and morphological properties of the synthesized core–shell nanoparticles were characterized by an X-ray diffraction, UV–vis absorption spectroscopy, photoluminescence spectroscopy and high-resolution transmission electron microscopy techniques. The X-ray diffraction analysis of the synthesized core–shell nanoparticles confirms the formation of cubic phase. The absorption and emission spectra of the synthesized core–shell nanoparticles show the red shift with respect to the CdS shell thickness on Zn-doped CdSe core. High-resolution transmission electron microscopy images display the synthesized core–shell nanoparticles were in spherical shape.

Response of iron oxide on hetero-nanostructures of soft and hard ferrites

Core-shell nanostructures of Zinc and Cobalt ferrites synthesized by solution evaporation route are observed to perform novel magnetic response. The structural and morphological analyses of ZnFe2O4−core/Fe3O4−shell and CoFe2O4−core/Fe3O4−shell nanoparticles (NPs) are confirmed with X-ray diffractometer (XRD) and high resolution transmission electron microscopy (HRTEM). Physical properties measurement system (PPMS) investigations at room temperature reveal that the synthesized core-shell NPs (∼8 nm in diameter) are in super-paramagnetic state. The coercivity of ZnFe2O4/Fe3O4 is much lower than that of CoFe2O4/Fe3O4 NPs (e.g., at 5 K: Hc=0.6kOe for ZnFe2O4/Fe3O4 and Hc = 18kOe for CoFe2O4/Fe3O4. Fe3O4 is preferable to reduce magnetic hardness for Zinc ferrite and enhance for Cobalt Ferrite.