Core-shell Structure Nanoparticles Research Articles

Multifunctional Fe3O4@CuS nanoparticle-driven colorimetric and photothermal immunochromatographic test strip for the sensitive detection of Salmonella typhimurium in milk

Magnetic nanoparticles are widely employed as signal labeling reporters in immunochromatographic test strips (ICTS) for detecting foodborne pathogens due to their outstanding anti-interference and magnetic enrichment performance. However, the insufficient colorimetric signal brightness of magnetic nanoparticles results in poor sensitivity, hindering their ability to meet the growing demand for advanced ICTS. Herein, we synthesized Fe3O4@CuS core-shell structure nanoparticles using a facile in-situ growth method. These Fe3O4@CuS nanoparticles exhibit a superior photothermal conversion efficiency of 42.12 % and a magnetization strength of 35 emu/g. We developed a dual-readout format ICTS based on Fe3O4@CuS, incorporating both colorimetric and photothermal formats to enhance sensitivity for Salmonella typhimurium detection. The limit of detection for Fe3O4@CuS-ICTS in the colorimetric and photothermal format was 5 × 10⁴ CFU/mL and 7.7 × 10³ CFU/mL, respectively. Additionally, the average recoveries ranged from 91.25 % to 103.39 %, with variations from 2.2 % to 11.1 %, demonstrating good accuracy and precision. Therefore, this work suggests that Fe3O4@CuS nanoparticles, with their superior magnetic, optical, and photothermal properties, can serve as promising signal labeling reporters to improve the detection performance of ICTS and hold potential for constructing more accurate and sensitive point-of-care testing platforms.

C@Ag core-shell structure as lubricating additives towards high efficient lubrication

Efficient cooperative lubrication can be achieved via the introduction of core-shell structure lubricant additives with hard core and soft shell, for obtaining the expected anti-wear performance from the structural changes in the friction process. In this study, C@Ag microspheres with a core-shell structure were prepared by the redox method with carbon spheres as the core and Ag nanoparticles as the shell. Their tribological behaviors as base oil (G1830) additive with different concentrations were investigated in detail. Compared with base oil, the addition of C@Ag particles at 0.5 wt% can reduce the coefficient of friction (COF) and wear volume (Wv) up to 15.5% and 88%, respectively. More importantly, C@Ag particles provide superior lubrication performance to single additive (like carbon sphere (CS) and Ag nanoparticle). C@Ag core-shell particles contribute to the formation of tribo-film by melt bonding of flexible Ag and carbon sphere (CS) toward excellent self-repair performance and high-efficiency lubrication. Hence, core-shell structural nanoparticles with hard-core and soft-shell hold bright future for high-performance lubrication application.

Microstructure and properties of oxide-reinforced FeCrAl matrix alloy manufactured by selective laser melting

In this work, nano-Y2O3 dispersed FeCrAl powders (NYD-Fe) were used to produce oxide dispersion strengthened (ODS) alloy by selective laser melting (SLM), and their microstructures and properties were investigated in detail by the kinds of characterization techniques. The results indicate that the Y2O3 particles adhered to the surface of FeCrAl powder absorb more laser, thus increasing the laser energy demand. High quality ODS deposits can be obtained at 600 mm/s and 180 W parameters. The ODS samples deposited by SLM exhibit coarse columnar grains with [001] texture. The Ti-rich nanoparticles and core-shell structured nanoparticles (Y- and O-rich core surrounded by a Ti-rich shell) are observed in ODS alloys. The precipitation formation of core-shell structured nanoparticles involves ball milling amorphization and dissolution reprecipitation. The ODS-180 alloy exhibits a higher ductility compared to FeCrAl-180 alloy, which is caused by the cellular structure with high density dislocations and the nano-sized precipitates inhibit the dislocation motion. The wear rate of the ODS-180 alloy is 51% lower than that of FeCrAl-180 alloy, which is mainly ascribed to the hardness and interface oxide layer resulting from its specific microstructural features.

Chemical synthesis of Mn–Zn magnetic ferrite nanoparticles: Effect of secondary phase on extrinsic magnetic properties of Mn–Zn ferrite nanoparticles

This paper presents a comprehensive investigation of the magnetic properties of co-precipitated MnxZn1–xFe2O4 nanoferrites, where x takes the values of 0.5, 0.6, and 0.7. X-ray diffraction patterns indicated the presence of spinel phase. However, the ferrite composition x = 0.6 contains little trace of secondary phase α-Fe2O3. The occurrence of cation redistribution in the current ferrite samples can be concluded from the deviation of oxygen position parameter (U) to that of optimum value (0.375). The bond angles facilitate the reduction of the A–B interaction and the increase of the B–B interaction. With the substitution of Mn2+ ions, the saturation magnetization (Ms) exhibits both drops and increases whereas the coercivity (Hc) consistently declines. The ferrite composition x = 0.7 exhibits the maximum value of Ms and is equal to 27.9 emu/g. The blocking temperature (TB) rises in proportion to the degree of Mn2+ ion doping. The observation of quadruple doublets in the Mӧssbauer spectra indicates that the ferrite nanoparticles exist in single domain state exhibiting the quadruple interactions. The range of isomer shift (δ) 0.199–0.267 mm/s indicates the existence of exclusively high spin Fe3+ ions. Two paramagnetic doublets are anticipated to exist as a result of the core and shell of present ferrite nanoparticles. In the core-shell morphology of nanoparticles, the core is characterized by larger quadruple splitting (Δ) while the shell is characterized by smaller Δ. The results are integrated in terms of magnetocrystalline anisotropy and secondary phase presuming the core-shell structure of nanoparticles.

Effect of ligand and shell densities on the surface structure of core-shell nanoparticles self-assembled from function-spacer-lipid constructs.

Biomolecular corona is the major obstacle to the clinical translation of nanomedicines. Since corona formation is governed by molecular interactions at the nano-bio interface, nanoparticle surface properties such as topography, charge and surface chemistry can be tuned to manipulate biomolecular corona formation. To this end, as the first step towards a deep understanding of the processes of corona formation, it is necessary to develop nanoparticles employing various biocompatible materials and characterize their surface structure and dynamics at the molecular level. In this work, we applied molecular dynamics simulation to study the surface structure of organic core-shell nanoparticles formed by the self-assembly of synthetic molecules composed of a DOPE lipid, a carboxymethylglycine spacer and biotin. Lipid moieties form the hydrophobic core, spacer motifs serve as a hydrophilic shell and biotin residues function as a targeting ligand. By mixing such function-spacer-lipid, spacer-lipid and lipid-only constructs at various molar ratios, densities of the ligand and spacer on the nanoparticle surface were modified. For convenient analysis of the structure and dynamics of all regions of the nanoparticle surface, we compiled topography maps based on atomic coordinates. It was shown that an increase in the density of the shell does not reduce exposure of the core, but increases shell average thickness. Biotin, due to its alkyl valeric acid chain and spacer flexibility, is localized primarily near the hydrophobic core and its partial presentation on the surface occurs only in nanoparticles with higher ligand densities. However, an increase in biotin density leads to its clustering. In turn, ligand clustering diminishes the stealth properties of the shell and targeting efficiency. Based on nanoparticle surface structures, we determined the optimal density of biotin. Experimental studies reported in the literature confirm these conclusions. We also suggest design tips to achieve the preferred biotin presentation. Simulation results are consistent with the synchrotron SAXS profile. We believe that such studies will contribute to a better understanding of nano-bio interactions towards the rational design of efficient drug delivery systems.

Pore size-tunable core-shell structured Ni-Ru Nanoparticles catalyst for the reductive amination of isosorbide diketone

Isosorbide has been produced on a large scale and is expected to become the most important raw material for producing diaminoisomannide (DAIS) as a monomer for synthesis of polyamides. However, the direct catalytic amination of isosorbide to DAIS is impossible over heterogeneous catalysts, therefore, a two-step process, consisting of oxidation of isosorbide to isosorbide-diketone (ISDK) and reductive amination of ISDK to DAIS, has been proposed. The second step is key to realize this process. Therefore, a series of core-shell structured Ni-Ru nanoparticles bimetallic catalysts (Ni-Ru@SiO2 and meso-Ni-Ru@SiO2) for the reductive amination of ISDK to DAIS have been developed by doping ruthenium to Ni@SiO2. Among the catalysts, the meso-Ni-Ru@SiO2 catalyst (Ni: Ru = 76, Si: Ni = 0.625, C18TMS: Si = 0.2) demonstrated the highest catalytic activity in the catalytic amination of ISDK to DAIS, and the yield of DAIS reached up to 99 % with a turnover frequency (TOF) of 26.90 s−1. The catalyst also showed excellent performance in the catalytic amination of various aldehydes and ketones including (hetro)aromatic aldehydes and ketones as well as aliphatic aldehydes and ketones. The characterization results revealed that the Ni-Ru nanoparticles in the catalyst are uniformly dispersed and encapsulated within the SiO2 shell, and the doped Ru can adjust the electronic state of Ni. The porosity and pore size of the SiO2 shell can be tuned by adjusting the amount of C18TMS during the formation of the SiO2 shell, which facilitate the performance of the catalyst. Density functional theory (DFT) calculation in combination with experimental validation have shown that the porosity and pore size of the SiO2 shell affect the diffusion efficiency of reactants and products.

Rapid capture and quantification of food-borne spores based on the double-enhanced Fe3O4@PEI@Ag@PEI core-shell structure SERS sensor

To realize rapid capture and quantification of food-borne spores and prevent their potential harm, Fe3O4@PEI@Ag@PEI core-shell structure nanoparticles were combined with flower-like AgNPs for double enhancement and efficient capture of spores. The developed sensor showed excellent reproducibility and SERS enhancement factor (AEF) is 4.6 × 104. Orthogonal partial least-squares discrimination analysis and linear discriminant analysis accurately identified the three spores (Bacillus subtilis, Bacillus cereus, and Clostridium perfringens), and the qualitative identification accuracy of linear discriminant analysis was 100 %. Efficient enrichment of B. subtilis spores was realized within 5 min, with a detection limit of 3 cfu/mL. Spiked tests revealed that this sensor was effective in detecting spores in milk, orange juice, and water samples, with recovery ratio of 95.2−103.9 % and relative standard deviation of 3.1−7.7 %. Thus, the developed sensor was accurate and reliable, and could achieve rapid identification and quantitative detection of food-borne spores.

Preparation of SiO2@Au Nanoparticle Photonic Crystal Array as Surface-Enhanced Raman Scattering (SERS) Substrate.

Surface-enhanced Raman scattering technology plays a prominent role in spectroscopy. By introducing plasmonic metals and photonic crystals as a substrate, SERS signals can achieve further enhancement. However, the conventional doping preparation methods of these SERS substrates are insufficient in terms of metal-loading capacity and the coupling strength between plasmonic metals and photonic crystals, both of which reduce the SERS activity and reproducibility of SERS substrates. In this work, we report an approach combining spin-coating, surface modification, and in situ reduction methods. Using this approach, a photonic crystal array of SiO2@Au core-shell structure nanoparticles was prepared as a SERS substrate (SiO2@Au NP array). To study the SERS properties of these substrates, Rhodamine 6G was employed as the probe molecule. Compared with a Au-SiO2 NP array prepared using doping methods, the SiO2@Au NP array presented better SERS properties, and it reproduced the SERS spectra after one month. The detection limit of the Rhodamine 6G on SiO2@Au NP array reached 1 × 10-8 mol/L; furthermore, the relative standard deviation (9.82%) of reproducibility and the enhancement factor (1.51 × 106) were evaluated. Our approach provides a new potential option for the preparation of SERS substrates and offers a potential advantage in trace contaminant detection, and nondestructive testing.

Simple design of upconversion nanoparticles-based aptasensor integrated microfluidic chip for ultra-sensitive detection of bisphenol A in aquatic products

Bisphenol A (BPA) is an endocrine disrupting chemical having estrogenic properties that can enter the body through leaking from food containers or the food chain. An upconversion nanoparticle-based aptasensor integrated with microfluidic chip was simply designed to achieve the determination of BPA in foodstuff. Core-shell structured upconversion nanoparticles with 6.41-fold luminescence enhancement were used as fluorescence donors and gold nanoparticles as fluorescence acceptors to construct fluorescence resonance energy transfer (FRET) system. The BPA aptamer serves as a link between the building of the FRET system and the BPA-specific recognition component. The fishbone-structured microfluidic chip only needs 0.5 μL sample solution and 4 min to determine the presence of BPA. The proposed method has good linearity for BPA in the range of 0.02–100 ng/mL with calibration curve of y = 0.0918x + 0.6477 and limit of detection of 0.014 ng/mL. It is tremendously competitive to perform on-chip analysis that enables microsampling and rapid determination.

An innovative approach to photolithography for optical recording of high-resolution two-dimensional structures in a negative SU8 photoresist by activation of up-conversion luminescence in Yb[formula omitted] and Tm[formula omitted] doped NaYF[formula omitted] nanoparticles

In this work, we demonstrate the success of an innovative approach to photolithographic recording of high-resolution 2D structures in thin films of hybrid inorganic nanoparticles/photoresist systems. This is done by utilising Yb3+, Tm3+ up-conversion luminescence in core–shell (β-NaYF4:Yb3+, Tm3+/ β-NaYF4)-structured nanoparticles (33.9 nm in size) mixed into a negative photoresist SU8. This approach is a promising alternative compared to traditional optical lithography performed by i-line UV radiation through a surface. Specially designed core–shell-structured nanoparticles were synthetised to emit Tm3+-characteristic up-conversion luminescence bands in the UV spectral region at 345 and 361 nm, and in the blue spectral region at 450 and 476 nm under IR excitation at 976 nm. The exposed elliptically shaped uniform structure, with dimensions of ∼160 ×320μm, was recorded in a ∼500 nm thin photosensitive layer by 1–5 min long infrared exposure when core–shell nanoparticles doped with Yb3+ and Tm3+ ions were mixed into negative photoresist SU8. Such hybrid systems of organic chromophores/UCNP/SU8 are highly prospective for the fabrication of various types of microstructures without damaging the light-sensitive organic compound, which is required in medicine (microsurgery, laboratory on a chip, etc.), telecommunications, military, sensor technologies and a wide range of photonic applications, e.g. for the fabrication of micro disk resonators used as active media in organic solid-state lasers.

Core-Shell Structured Chitosan-Polyethylenimine Nanoparticles for Gene Delivery: Improved Stability, Cellular Uptake, and Transfection Efficiency.

The delivery of nucleic acids relies on vectors that condense and encapsulate their cargo. Especially nonviral gene delivery systems are of increasing interest. However, low transgene expression levels and limited tolerability of these systems remain a challenge. The improvement of nucleic acid delivery using depolymerized chitosan-polyethylenimine DNA complexes (dCS-PEI/DNA) is investigated. The secore complexes are further combined with chitosan-based shells and functionalized with polyethylene glycol (PEG) and cell penetrating peptides. This modular approach allows to evaluate the effect of functional shell components on physicochemical particle characteristics and biological effects. The optimized ternary complex combines a core-dCS-linear PEI/DNA complex with a shell consisting of dCS-PEG-COOH, which results in improved nucleic acid encapsulation, cellular uptake and transfection potency in human hepatoma HuH-7cells and murine primary hepatocytes. Effects on transgene expression are confirmed in wild-type mice following retrograde intrabiliary infusion. After administration of only 100 ng complexed DNA, ternary complexes induced a high reporter gene signal for three days. It is concluded that ternary coreshell structured nanoparticles comprising functionalized chitosan can be used for in vitro andin vivo gene delivery.

Modulating Pt Interaction in Au@Pt Nanoparticle/WO3 Photocatalysts for Enhanced Production of Peroxodisulphate

Production of peroxodisulphate (S2O82–) on powdered photocatalysts is a promising way to obtain high-value-added chemicals using solar energy; however, it is still suffering from low efficiency. In the present work, we fabricated bimetallic Au core and Pt shell nanoparticle-loaded WO3 (Au@Pt/WO3) photocatalyst for enhanced production of S2O82–, which is 1.7 times that of Pt nanoparticle-loaded WO3 (Pt/WO3), and was reported to be the best catalyst for S2O82– production. A further study demonstrated that the electronic interaction of Pt was successfully modulated by the core–shell nanoparticle architecture, and the core–shell nanoparticle structure between Au and Pt improved the formation of the surface chemical state of Pt to be metallic Pt, proposed as the active site for oxygen reduction. Besides, the core–shell nanoparticle structure also exposed a large amount of Pt on the surface of the substrate. As a result, Au@Pt/WO3 showed significantly enhanced photocatalytic activity of S2O82– with a quantum efficiency of 5.2% at 420 nm, whereas Pt–Au bimetallic alloy nanoparticle-loaded WO3 with a large amount of surface PtOx and exposed both Au and Pt on the surface showed very low activity. This work provides insights into the bimetallic Pt nanoparticle-loaded WO3 for enhanced photocatalytic activity.

Tuning interfacial relaxations in P(VDF-HFP) with Al2O3@ZrO2 core-shell nanofillers for enhanced dielectric and energy storage performance

High energy density is a desirable index for advanced energy storage materials. Here, core-shell structured nanoparticles Al2O3@ZrO2 (A@Z) are synthesized to fabricate P(VDF-HFP)/A@Z nanocomposite films. Experimental and simulation results confirm that A@Z nanoparticles are effective in suppressing the local electric field distortion of nanocomposites, as well as intensifying the interfacial polarization without affecting the intrinsic orientational polarization. The activation energy of the interfacial relaxation in crystalline/amorphous region is increased from 0.96 eV of the neat P(VDF-HFP) to 1.25 eV of P(VDF-HFP)/5 vol%-A@Z nanocomposite. Meanwhile, a new dielectric relaxation with energy of ∼1.08 eV related to nanoparticles/amorphous phase of P(VDF-HFP) is induced. The modulated interfaces present substantial capability in inhibiting charge motion, which contributes to an improved electrical property and energy density of the nanocomposites. Specifically, a ∼200% enhancement in discharged energy density is achieved in the P(VDF-HFP)/5 vol%-A@Z nanocomposite, demonstrating a promising dielectric material choice for energy storage capacitor applications.

Study of Electrokinetic Properties of Magnetite – Silica Core – Shell Nanoparticles

In this work, the electrokinetic properties of Fe3O4 nanoparticles modified with various alkoxysilanes (tetraethoxysilane and 3-aminopropyltriethoxysilane) in various media were investigated. The determined values of the zeta potential of the Fe3O4/SiO2 samples indicate the complete coverage of nanoparticles with a tetraethoxysilane shell, as well as in the case of the Fe3O4/aminopropyltriethoxysilane. The data obtained on the zeta-potentials of modified nanoparticles with various ligands make it possible to predict the efficiency of subsequent functionalization by target molecules. A decisive role in the study of surface properties is played by cleaning from low molecular weight impurities that can screen the surface of nanoparticles or bind with an indifferent electrolyte. Thus, dispersion on a magnetic stirrer leads to an increase in the sorption capacity of the sample in comparison with ultrasonic dispersion, which causes irreversible destruction of the core-shell nanoparticle structure due to an increase in temperature and pressure in the cavities. This opens the prospective for practical application of modified nanoparticles for creation of tailored composite materials.

Preparation and MRI performances of core-shell structural PEG salicylic acid-gadolinium composite nanoparticles

Gadolinium (III)-based T1 contrast agents have been widely used in clinical MRI. In this study, salicylic acid-gadolinium chelate was prepared via directly coordination reaction of gadolinium ion and salicylic acid. Then, three polyethylene glycols with different molecular weight were modified on the surface of salicylic acid-gadolinium by simple chemical coupling to construct three core-shell structural Gd based composites. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) characterization results show that the composite is a spherical particle with a diameter of about 100–200 nm. The longitudinal relaxation rate r1 of the Gal-PEG-2000 is 11.097 (mmol/L)−1/s, and the ratio of r2/r1 is as low as 2.53. The composite shows good liver and intestines MRI performances after being used in in vivo imaging, showing a good prospect of biological application.

Use of single particle inductively coupled plasma mass spectrometry for understanding the formation of bimetallic nanoparticles

Bimetallic nanoparticles (NPs), including core-shell structure and bimetallic alloy nanoparticles, were synthesized and characterized using flow field-flow fractionation (FlFFF), single particle inductively coupled plasma mass spectrometry (SP-ICP-MS), and transmission electron microscope (TEM) with energy-dispersive x-ray spectroscopy (EDS). For the core-shell particles, a nominal 80 nm commercial core-shell AuAg bimetallic nanoparticle was used to examine the applicability of SP-ICP-MS to determine the core size of Au and shell thickness of Ag. Then, the method was applied to estimate the core size of Au and shell thickness of Ag for the laboratory synthesized particles. The results were compared with those obtained from TEM-EDS. For the alloy nanoparticles, two synthesis protocols, based on the galvanic replacement of Ag seed particles with Au, were used. One was to prepare a hollow AgAu particle by varying the volume of dissolved Au in basic solution (K-gold) to etch some parts of AgNPs to dissolved ionic silver with the formation of AuNPs covering the remaining AgNPs, producing a hole inside the core nanoparticles. Another protocol was to prepare AgAu alloy nanoparticles. SP-ICP-MS was used in combination with FlFFF to provide information on the changes of particle size with varying volume of K-gold reagent. Hydrodynamic diameter increased with increasing K-gold, as observed by FlFFF. With SP-ICP-MS without prior FlFFF, bimodal distributions were observed in the size distribution of Au and Ag. With prior FlFFF, monomodal distributions were observed by SP-ICP-MS, which allow the use of particle concentration and size to estimate the mass concentration of elements on the fractionated bimetallic nanoparticles. This study illustrates the potential use of SP-ICP-MS for gaining information about particle transformation during the synthesis of bimetallic nanoparticles.

Selective emitter with core–shell nanosphere structure for thermophotovoltaic systems

For thermophotovoltaic (TPV) systems, traditional thermal emitters waste considerable energy due to the mismatch between the thermal radiation power spectrum and the bandgap of the photovoltaic (PV) cells. Here, a core–shell nanosphere (CSN) structured selective emitter was designed and optimized on the basis of numerical calculation. By iteratively optimizing the geometric parameters of the CSN emitter, the average emissivity of the CSN emitter exceeds 0.93 within the bandgap and is suppressed to 0.13 outside the bandgap. The mechanism of selective emission characteristics is elucidated in detail. Additionally, the simulation results demonstrate that the CSN emitter exhibits emissivity insensitivity to polarization and incident angle. For the TPV system with the InGaAs cells, an output power density of 0.594 W/cm2 and a system efficiency of 12.83% are achieved at a CSN emitter temperature of 1338 K. The obtained output power density is relatively high, i.e., 3.2 times that of the previously reported record (0.184 W/cm2). And ultimately, the core–shell structural nanoparticles were synthesized by solution–processed and their performance was tested. This research improves the performance of the selective emitter and paves the way for a more efficient design of TPV systems.

Significantly Enhanced Overall Water Splitting Performance by Partial Oxidation of Ir through Au Modification in Core–Shell Alloy Structure

Developing efficient bifunctional electrocatalysts for overall water splitting in acidic conditions is the essential step for proton exchange membrane water electrolyzers (PEMWEs). We first report the synthesis of core-shell structure nanoparticles (NPs) with an Au core and an AuIr2 alloy shell (Au@AuIr2). Au@AuIr2 displayed 4.6 (5.6) times higher intrinsic (mass) activity toward the oxygen evolution reaction (OER) than a commercial Ir catalyst. Furthermore, it showed hydrogen evolution reaction (HER) catalytic properties comparable to those of commercial Pt/C. Significantly, when Au@AuIr2 was used as both the anode and cathode catalyst, the overall water splitting cell achieved 10 mA/cm2 with a low cell voltage of 1.55 V and maintained this activity for more than 40 h, which greatly outperformed the commercial couples (Ir/C||Pt/C, 1.63 V, activity decreased within minutes) and is among the most efficient bifunctional catalysts reported. Theoretical calculations coupled with X-ray-based structural analyses suggest that partially oxidized surfaces originating from the electronic interaction between Au and Ir provide a balance for different intermediates binding and realize significantly enhanced OER performance.

Preparation of BaTiO3@NiO core-shell nanoparticles with antiferroelectric-like characteristic and high energy storage capability

A core-shell structural nanoparticles preparative technique was applied to produce BaTiO3@NiO ceramics with excellent energy storage performance. Shell layers of NiO were coated onto BaTiO3 nanoparticles by sol-precipitation method. The structures, dielectric and energy storage properties of the BaTiO3@NiO ceramics were systematically investigated. Results show that, high-densification microstructures with fine-crystalline and uniform distribution are observed in all the ceramics, and excellent energy storage density of 2.72 J cm−3 with low remnant polarization is achieved at 230 kV cm-1 in BaTiO3@1 %NiO ceramics, which also possesses fast discharge features (τ0.9<2 μs), superior thermal stability (20–80 °C) and prominent cyclic stability (up to 1 × 105 times). Moreover, the BaTiO3@NiO ceramics exhibits an antiferroelectric-like feature due to the synergistic effect of NiO and BaTiO3. The antiferroelectric-like dielectric material could be a prospective material for energy storage application.

Biomass-derived ultrathin carbon-shell coated iron nanoparticles as high-performance tri-functional HER, ORR and Fenton-like catalysts

The development of cost-effective carbon-shell coated metal-based nanocatalysts is currently a highly desirable goal towards the fabrication of more sustainable non-precious nanocatalysts. Herein, we design an easy, cheap, scalable, and eco-friendly carbothermal reduction strategy to develop core-shell structured metallic iron nanoparticles using coffee waste grounds as starting renewable materials (Fe@BMC). The structural properties of the as-synthesized nanoparticles were nicely tuned by varying the reaction temperature. Remarkably, ultrathin carbon-shell coated metallic iron nanoparticles were obtained at 800 °C, which was clearly elucidated by the HRTEM, XRD, and XPS measurements. The Fe-800 °C@BMC nanocatalyst showed excellent properties as an ORR electrocatalyst with an onset potential of 0.93 V vs RHE, keeping 90% of the initial current applied after the 20000s. Noticeably, the Fe-800 °C@BMC carbon-shell nanostructures delivered a Pt-like performance with a very low onset potential of −25 mV vs RHE, an overpotential of 75 mV at a current density of 10 mA cm−2 and an ultrahigh stability to keep the 99% of the initial current applied after 20000s, behaving like one of the most efficient HER core-shell structured non-precious electrocatalysts reported up to now. Also, the Fenton like catalytic studies revealed that the Fe-800 °C@BMC nanocatalyst was so far the most active catalyst for the degradation of tetracycline (TC) antibiotic allowing the degradation of 95.72% of TC in 45 min with a higher reaction rate constant of 0.068 min−1. The impressive catalytic behavior of the Fe-800 °C@BMC nanocatalyst was attributed to the hierarchically porous carbon network as well as to the synergistic interaction between the encapsulated metallic iron core and the ultrathin carbon shell, which regulate the adsorption energy of the reactive species. The present work offers new insights into the development of scalable and high-performance tri-functional catalysts through a sustainable and low-cost synthetic route.