Core-shell Hybrid Materials Research Articles

Efficient Analysis of Small Molecules via Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (LDI-TOF MS) Using Gold Nanoshells with Nanogaps.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is a commonly used technique for analyzing large biomolecules. However, the utilization of organic matrices limits the small-molecule analysis because of the interferences in the low-mass region and the reproducibility issues. To overcome these limitations, a surface-assisted laser desorption/ionization (SALDI), which utilizes nanostructured metallic surfaces, has been developed. Herein, a novel approach for SALDI-MS was proposed using silica@gold core-shell hybrid materials with a nanogap-rich shell (SiO2@Au NGS), which is an emerging material due to its excellent heat-generating capabilities. The gold shell thickness was controlled by adjusting the concentration of gold precursor for the growth of gold nanoparticles. SALDI-MS measurements were performed on a layer formed by drop-casting a mixture of SiO2@Au NGS and analytes. At the optimized process, the gold shell thickness was observed to be 17.2 nm, which showed the highest absorbance. Based on the enhanced SALDI capability, SiO2@Au NGS was utilized to detect various small molecules, including amino acids, sugars, and flavonoids, and the ionization softness was confirmed with a survival yield upon fragmentation. The limits of detection, reproducibility, and salt tolerance of SiO2@Au NGS demonstrate its potential as an effective and reliable SALDI material for small-molecule analyses.

The mega-merger strategy: M@COF core-shell hybrid materials for facilitating CO2 capture and conversion to monocyclic and polycyclic carbonates

Metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) have garnered significant attention for their potential in CO2 capture and conversion, owing to their unique properties. However, these materials suffer from inherent drawbacks such as poor stability and catalytic activity, leading to unsatisfactory utilization efficiency. In this work, we fabricated a series of novel M@COF hybrid materials by growing pyridine-based COFs with varying thicknesses on NH2-UiO-66 cores. These materials exhibited large specific surface areas and favorable chemical stability. The combination of the high specific surface area of MOF and the multiple interacting π-π stacking interactions of COF in these M@COF hybrid materials resulted in significantly enhanced CO2 adsorption performance, surpassing that of individual parent MOF or COF. In addition, an ion-functionalized M@COF-0.15-Br was fabricated through a simple post-synthesis modification. The presence of abundant ion active sites and interfacial synergistic effects in M@COF-0.15-Br effectively facilitated activation of reactants, enabling efficient catalytic conversion of CO2 to monocyclic and polycyclic carbonates. Consequently, the superior CO2 capture and conversion achieved using this M@COF core-shell hybrid material offers a new approach to design advanced functional materials with optimized structures for CO2 capture and conversion.

Construction of core–shell MOF@COF hybrid materials as highly efficient light-responsive oxidase-like nanozymes for colorimetric detection of glutathione

In this work, a novel and light-responsive nanozyme, with enzyme-like characteristics, was synthesized based on core–shell MOF@COF hybrid materials. The donor–acceptor type COF (as shell) synthesized by 1,3,6,8-tetrakis(4-aminophenyl)pyrene (Py, donor) and thieno[3,2-b]thiophene-2,5-dicarbaldehyde (Tt, acceptor) was wrapped on the NH2-Cu-MOF (robust catalyst, as core) through a sequential growth strategy. Surprisingly, with visible-light irradiation, the core–shell Cu-MOF@Py-Tt hybrid materials exhibited extremely high oxidase-like enzymatic catalytic activity attributing to the high separation efficiency of photogenerated carriers in core–shell hybrid materials and the shell with the characteristics of large π-conjugated and D-A electronic structure. With the light-control catalytic activity, Cu-MOF@Py-Tt can form the O2•- that can catalyze the TMB to blue color. Consequently, a light-control, sensitive and rapid colorimetric method for determination of glutathione (GSH) was designed based on light-responsive oxidase mimic of core–shell Cu-MOF@Py-Tt with the linear range of 0.2–70 μM and limit of detection of 0.17 μM. The proposed method demonstrated the future potential of core–shell MOF@COF hybrid materials to obtain excellent nanozyme activity.

Fabrication of hierarchical core–shell carbon microspheres@ layered double hydroxide@ polyphosphazene architecture in flame‐retarding polypropylene

Developing advanced performance polypropylene (PP) composites with less smoke, eco-friendly and efficient flame retardants (FRs) has been a growing focus of research. In particular, it was significant to reduce the emissions of smoke and toxic gases generated during the burning of PP so that it meets green and safe industrial requirements. In this work, a CMSs@LDH@PZN hierarchical core–shell framework was designed and synthesized by using carbon microspheres (CMSs) and layered double hydroxides (LDHs) nanosheets connected to CMSs by electrostatic forces with polyphosphazene (PZN). The structure, composition and morphology of CMSs@LDH@PZN were characterized by SEM, TEM, FT-IR, XRD and TG, and the results were shown the triumphant preparation of the well-designed hierarchical core–shell structure CMSs@LDH@PZN. Additionally, the total smoke production, peak heat release rate and total heat release rate of PP/CMSs@LDH@PZN composites were decreased by 56.2%, 41% and 43.4%, respectively. With the addition of 20 wt% CMSs@LDH@PZN alone, the PP/CMSs@LDH@PZN composites reached a V-0 rating in the Vertical combustion tester (UL-94), and had a limiting oxygen index (LOI) value of 29.6%. Moreover, the heat release and toxic smoke emission were significantly lessened, which can be own to the adsorption of core–shell hybrid materials and the barrier effect of the P and N element crosslinked carbon layer. Herein, this work extends the idea of preparing multipurpose high-performance composites and designs and synthesizes an eco-friendly and efficient flame retardant with a double shell structure.

Essential role of the interfacial interaction in the core-shell electrode for its enhanced electrochemical performance

Interfacial interaction in the core-shell hybrid materials makes a great influence for the enhanced electrochemical performances. In this paper, to explore the essential role of the interfacial interaction in the core-shell hybrid electrodes, we prepare a simple mutually-coupled 3D heterogeneous core/shell electrode by NiFe PBAs (Prussian blue analogues) (shell) depositing on the surface of NiFe LDH (layered double hydroxides) (core). The elements of Fe and Ni in NiFe LDH can partly replace the original connections in the NiFe PBAs thus forming a strong interfacial coordination bonding between LDH and PBAs (Fe/Ni(LDH)–CN–Fe/Ni(PBAs) or O–Fe/Ni(PBAs)). Electrochemical tests show that the hybridization present excellent electrochemical performances with a high capacity of 1351 F g−1 at 1 A g−1, which is much higher than that of PBAs-based electrodes recently report. In-situ Raman spectroscopic analysis shows that NiFe LDH@NiFe PBAs present enhanced Faradic redox reaction during charging/discharging process, which is owing to the strong interfacial interaction between two phases. The density functional theory (DFT) calculations results demonstrate that the strong connection bonding can improve the electrical conductivities greatly. This work underscores the crucial role of interface coupling interaction between core and shell and give a new perspective to design core-shell hybrid electrode with excellent electrochemical performance.

Polyampholytic Graft Copolymers as Matrix for TiO2 /Eosin Y/[Mo3 S13 ]2- Hybrid Materials and Light-Driven Catalysis.

An effective strategy to enhance the performance of inorganic semiconductors is moving towards organic‐inorganic hybrid materials. Here, we report the design of core–shell hybrid materials based on a TiO2 core functionalized with a polyampholytic (poly(dehydroalanine)‐graft‐(n‐propyl phosphonic acid acrylamide) shell (PDha‐g‐PAA@TiO2). The PDha‐g‐PAA shell facilitates the efficient immobilization of the photosensitizer Eosin Y (EY) and enables electronic interactions between EY and the TiO2 core. This resulted in high visible‐light‐driven H2 generation. The enhanced light‐driven catalytic activity is attributed to the unique core–shell design with the graft copolymer acting as bridge and facilitating electron and proton transfer, thereby also preventing the degradation of EY. Further catalytic enhancement of PDha‐g‐PAA@TiO2 was possible by introducing [Mo3S13]2− cluster anions as hydrogen‐evolution cocatalyst. This novel design approach is an example for a multi‐component system in which reactivity can in future be independently tuned by selection of the desired molecular or polymeric species.

Hybridization of MOFs and ionic POFs: a new strategy for the construction of bifunctional catalysts for CO2 cycloaddition

A new strategy toward constructing a bifunctional catalyst for CO2 cycloaddition has been developed on the basis of post-synthetic modification of CUS-based MOFs with ionic POFs to form MOF@iPOF core–shell hybrid materials.

Crystal engineering of MOF@COF core-shell composites for ultra-sensitively electrochemical detection

Exploration and construction of novel porous core-shell composites is of crucial significance due to their prospectively enhanced performances and far-ranging applications. Herein, microporous UiO-66-NH2 as a MOF core is coated by a mesoporous TAPB-DMTP−COF shell to construct the UiO-66-NH2@COF composite via a covalent linking approach. Importantly, the composite with retentive crystallinity and hierarchical porosity significantly improves the electrochemical detection performance, for instance ATP and antibiotic, because this composite has the high affinity between the phosphate groups of aptamers and dense Zr(IV) sites, and strong π-π stacking interaction between aptamers and this MOF@COF. The synthetic strategy in this systematic research expands a rational design for other MOF@COF core-shell hybrid materials to expand their promising applications.

Preparation of CuO@PPy hybrid nanomaterials as high cyclic stability anode of lithium‐ion battery

Over the recent 20 years, numerous researches have focused on the lithium-ion batteries anodes of MOx 3d-metal oxides which have a high specific capacity. For example, the specific capacity of CuO material as an anode is ∼670 mAh g−1. Unfortunately, serious capacity degradation limits their promising applicability. To improve cyclic stability, PPy is covered on CuO surface to prepare CuO@PPy core–shell hybrid materials by chemical polymerisation. Pyrrole amount plays an important role on control the PPy shell thickness. After PPy coating, the lithium-ion battery cycling stability and coulombic efficiency have been improved greatly, and CP-5 sample has the best cyclic stability and coulombic efficiency. The capacity retention of bare CuO is only 27.9% after 200 cycles. By contrast, the capacity retention of CP-5 sample is ∼100%. The flexible conducting polymers shell (PPy) lead to improved cyclic stability. These results give a strategy to solve MOx 3d-metal oxide capacity degradation as Lithium-ion batteries anode.

Surface Functionalization of Magnetic Nanoparticles Using a Thiol-Based Grafting-Through Approach

Here we describe a simple and straightforward synthesis of different multifunctional magnetic nanoparticles by using surface bound thiol-groups as transfer agents in a free radical polymerization process. The modification includes a first step of surface silanization with (3-mercaptopropyl)trimethoxysilane to obtain thiol-modified nanoparticles, which are further used as a platform for modification with a broad variety of polymers. The silanization was optimized in terms of shell thickness and particle size distribution, and the obtained materials were investigated by dynamic light scattering (DLS), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDX). Subsequently, the free radical polymerization of different monomers (tert-butyl acrylate (tBA), methyl methacrylate (MMA), styrene, 2-vinyl pyridine (2VP), and N-isopropylacrylamide (NIPAAm)) was examined in the presence of the thiol-modified nanoparticles. During the process, a covalently anchored polymeric shell was formed and the resulting core–shell hybrid materials were analyzed in terms of size (DLS, TEM), shell thickness (TGA, TEM), and the presence of functional groups (attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FT-IR)). Hereby, the shell leads to a different solution behavior of the particles and in some cases an increased stability towards acids. Moreover, we examined the influence of the nanoparticle concentration during polymerization and we found a significant influence on dispersity of the resulting polymers. Finally, we compared the characteristics of the surface bound polymer and polymer formed in solution for the case of polystyrene. The herein presented approach provides straightforward access to a wide range of core–shell nanocomposites.

Co3 O4 @Cu-Based Conductive Metal-Organic Framework Core-Shell Nanowire Electrocatalysts Enable Efficient Low-Overall-Potential Water Splitting.

In the work reported herein, the electrocatalytic properties of Co3 O4 in hydrogen and oxygen evolution reactions have been significantly enhanced by coating a shell layer of a copper-based metal-organic framework on Co3 O4 porous nanowire arrays and using the products as high-performance bifunctional electrocatalysts for overall water splitting. The coating of the copper-based metal-organic framework resulted in the hybridization of the copper-embedded protective carbon shell layer with Co3 O4 to create a strong Cu-O-Co bonding interaction for efficient hydrogen adsorption. The hybridization also led to electronically induced oxygen defects and nitrogen doping to effectively enhance the electrical conductivity of Co3 O4 . The optimal as-prepared core-shell hybrid material displayed excellent overall-water-splitting catalytic activity that required overall voltages of 1.45 and 1.57 V to reach onset and a current density of 10 mA cm-2 , respectively. This is the first report to highlight the relevance of hybridizing MOF-based co-catalysts to boost the electrocatalytic performance of nonprecious transition-metal oxides.

In situ generated 3D hierarchical Co3O4@MnO2 core–shell hybrid materials: self-assembled fabrication, morphological control and energy applications

A new series of highly ordered 3D hierarchical Co3O4@MnO2 core–shell hybrid materials was developed by a simple in situ self-assembly strategy for two typical energy applications in DSSCs and AP decomposition with superior performances.

Magnetic solid phase extraction of trace paracetamol and caffeine in synthetic urine and wastewater samples by a using core shell hybrid material consisting of graphene oxide/multiwalled carbon nanotube/Fe3O4/SiO2

A new hybrid material was synthesized including magnetic graphene oxide/multiwalled carbon nanotube core shell (GO/MWCNT/Fe3O4/SiO2) and used as magnetic solid phase extraction adsorbent for separation and pre-concentration of paracetamol and caffeine subsequent detection by high performance liquid chromatography. The morphology, composition, and properties of the synthesized hybrid material was characterized by Fourier transform infrared spectrometry, Raman spectrometry, X-ray diffraction spectrometry, scanning electron microscopy, mapping photographs and BET surface area analysis. The experimental variables on the extraction efficiency were studied and optimized. The optimum conditions for quantitative extraction of paracetamol and caffeine were obtained as of adsorbent amount, 70 mg; pH, 8.0; and elution with 1 mL of methanol by vortex mixer for 60 s. Validation experiments showed that the developed method had good linear ranges 5–800 ng mL−1 for caffeine and 10–1000 ng mL−1 for paracetamol, respectively. The limits of detection were found as 1.48 and 3.32 ng mL−1 for caffeine and paracetamol, respectively. The accuracy of the developed magnetic solid phase extraction method was proved by addition-recovery tests by using model solutions and the developed method was successfully applied for the determination of paracetamol and caffeine in synthetically prepared urine and waste water samples.

In situ induced core/shell stabilized hybrid perovskites via gallium(iii) acetylacetonate intermediate towards highly efficient and stable solar cells

Introduction of gallium(iii) acetylacetonate (GaAA3) induced CsxFA1−xPbI3–[GaAA3]4 (0 < x < 1) core–shell hybrid-materials based perovskite solar cell with remarkably high stability.

Silica@layered double hydroxide core-shell hybrid materials.

A series of silica@layered double hydroxides (SiO2@Mg2Al-CO3-AMO-LDHs) have been synthesised by in situ precipitation of Mg2Al-CO3-LDH at room temperature in the presence of amorphous spherical silica particles (∼500 nm). We have systematically investigated a number of synthetic parameters in order to evaluate their effects on the composition, morphological and physical properties of the isolated materials. Syntheses carried out at moderate stirring speeds (e.g. 500 rpm) were found to promote the formation of vertically aligned LDH platelets with respect to the silica surface. Addition rates of the metal solutions slower than 0.43 mmol h-1 were found to create a thicker LDH shell consisting of vertically aligned LDH platelets. When the metal solutions were added rapidly (0.86 mmol h-1), we observed that for both slow and fast stirring speeds the synthesised core-shell materials had thin LDH shells and the majority of the LDH precipitated independent of the silica, forming unbound "free" LDH.

Self-Assembled Core-Shell CdTe/Poly(3-hexylthiophene) Nanoensembles as Novel Donor-Acceptor Light-Harvesting Systems.

The self-assembly of novel core-shell nanoensembles consisting of regioregular poly(3-hexylthiophene) nanoparticles (P3HTNPs) of 100 nm as core and semiconducting CdTe quantum dots (CdTeQDs) as shell with a thickness of a few tens of nanometers was accomplished by employing a reprecipitation approach. The structure, morphology, and composition of CdTeQDs/P3HTNPs nanoensembles were confirmed by high-resolution scanning transmission microscopy and dynamic light-scattering studies. Intimate interface contact between the CdTeQDs shell and the P3HTNPs core leads to the stabilization of the CdTeQDs/P3HTNPs nanoensemble as probed by the steady-state absorption spectroscopy. Effective quenching of the characteristic photoluminescence of CdTeQDs at 555 nm, accompanied by simultaneous increase in emission of P3HTNPs at 660 and 720 nm, reveals photoinduced charge-transfer processes. Probing the redox properties of films of CdTeQDs/P3HTNPs further proves the formation of a stabilized core-shell system in the solid state. Photoelectrochemical assays on CdTeQDs/P3HTNPs films show a reversible on-off photoresponse at a bias voltage of +0.8 V with a 3 times increased photocurrent compared to CdTeQDs. The improved charge separation is directly related to the unique core-shell configuration, in which the outer CdTeQDs shell forces the P3HTNPs core to effectively act as electron acceptor. The creation of novel donor-acceptor core-shell hybrid materials via self-assembly is transferable to other types of conjugated polymers and semiconducting nanoparticles. This work, therefore, opens new pathways for the design of improved optoelectronic devices.

Hybridization of MOFs and COFs: A New Strategy for Construction of MOF@COF Core-Shell Hybrid Materials.

The exploration of new porous hybrid materials is of great importance because of their unique properties and promising applications in separation of materials, catalysis, etc. Herein, for the first time, by integration of metal-organic frameworks (MOFs) and covalent organic frameworks (COFs), a new type of MOF@COF core-shell hybrid material, i.e., NH2 -MIL-68@TPA-COF, with high crystallinity and hierarchical pore structure, is synthesized. As a proof-of-concept application, the obtained NH2 -MIL-68@TPA-COF hybrid material is used as an effective visible-light-driven photocatalyst for the degradation of rhodamine B. The synthetic strategy in this study opens up a new avenue for the construction of other MOF-COF hybrid materials, which could have various promising applications.

Core-shell zeolite@aqueous miscible organic-layered double hydroxides.

We report a general method for the synthesis of core-shell hybrid materials containing a microporous zeolite core with an aqueous miscible organic-layered double hydroxide (AMO-LDH) shell using a simple in situ coprecipitation method. For example, zeolite-HY@AMO-Mg2Al-CO3-LDH contains a 150 nm hierarchical AMO-Mg2Al-CO3-LDH surface coating on zeolite-HY. It exhibits a similar BET surface area (698 m2 g-1) as the parent zeolite-HY but this surface area has been re-allocated between microspores and mesopores. We believe that surface aluminium sites act as nucleation sites for the formation of the LDH coating and so robustly links it into the zeolite lattice. We expect that this new hybrid structure with micropores dominating in the core and mesopores populating the shell will provide a desirable new hybrid structure type for adsorption or catalysis.

Core–Shell Materials: Combination of HAADF‐STEM and ADF‐STEM Tomography for Core–Shell Hybrid Materials (Part. Part. Syst. Charact. 12/2015)

Core–Shell Materials: Combination of HAADF‐STEM and ADF‐STEM Tomography for Core–Shell Hybrid Materials (Part. Part. Syst. Charact. 12/2015)

Combination of HAADF‐STEM and ADF‐STEM Tomography for Core–Shell Hybrid Materials

Characterization of core–shell type nanoparticles in 3D by transmission electron microscopy (TEM) can be very challenging. Especially when both heavy and light elements coexist within the same nanostructure, artifacts in the 3D reconstruction are often present. A representative example would be a particle comprising an anisotropic metallic (Au) nanoparticle coated with a (mesoporous) silica shell. To obtain a reliable 3D characterization of such an object, a dose‐efficient strategy is proposed to simultaneously acquire high‐angle annular dark‐field scanning TEM and annular dark‐field tilt series for tomography. The 3D reconstruction is further improved by applying an advanced masking and interpolation approach to the acquired data. This new methodology enables us to obtain high‐quality reconstructions from which also quantitative information can be extracted. This approach is broadly applicable to investigate hybrid core–shell materials.