Core-shell Composites Research Articles

In-situ constructing nano ternary Ni-P-Cu alloy shell on the micro-aluminum surface: Enhancing its ignition and combustion performances

To improve the combustion efficiency of widely used micro-aluminum (μAl) particle, enhancing its ignition and combustion performances is a critical issue via breaking through the intrinsic Al2O3 layer covering the Al-core. This study proposed a facile in-situ ‘one-pot’ electroless plating method to functionalize the surface of μAl particles with ternary-shelled nickel-phosphorus-copper alloy coating and furthermore investigated the thermochemical and ignition/combustion behaviors of energetic core–shell composites (defined as Al@Ni-P-Cu). The microstructure characterization results of Al@Ni-P-Cu demonstrated that a spherically distributed triple-shell Ni-P-Cu alloy with the thickness of 129 nm was tightly coated on μAl particle surface. Through TG-DSC analysis, the Al@Ni-P-Cu composites exhibited improved heat release (7597.7 J/g) and decreased initial oxidation temperature (814.3 °C) in comparison to that of μAl particle with 949.2 J/g and 960.1 °C, respectively. The Al@Ni-P-Cu exhibited extremely shorter laser ignition delay time of 36.3 ms under 1 MPa O2 atmosphere, reducing by 86.86% compared with that of raw μAl particles (276.3 ms); and its maximum flame temperature could reach up to 1588.93 °C, increasing by 243.36 °C compared with that of μAl (1345.57 °C). The drastic improving performances were attributed to the synergistic effects of surface/interfaces reactions along with heat release in the core–shell structure, resulting in enhanced mass and heat transfer to facilitate the combustion of internal Al-core.

Dual-pathway optimization on microwave absorption characteristics of core–shell Fe3O4@C microcapsules: Composition regulation on magnetic core and MoS2 nanosheets growth on carbon shell

Core-shell Fe3O4@C composites with unique configuration and complementary loss mechanisms are widely considered as a kind of prospective functional materials in the field of microwave absorption. However, the balance between core–shell configuration and intrinsic loss is always a thorny problem on the way of good microwave absorption characteristics. Herein, we propose a dual-pathway optimization strategy to consolidate the electromagnetic functions of core–shell Fe3O4@C microcapsules for the first time. On one hand, the chemical composition of magnetic core is finely regulated from Fe3O4 to metal Fe, and it is found that both magnetic loss and dielectric loss can be strengthened effectively through the partial reduction of Fe3O4 core. On the other hand, MoS2 nanosheets are closely anchored on the surface of carbon shell, which can bring more powerful interfacial polarization and dipole polarization to compensate the insufficient dielectric loss caused by the limited thickness and graphitization degree of carbon shell. With the multiple benefits from the dual-pathway optimization strategy, the optimal composite will present good microwave absorption performance, whose effective absorption bandwidth (EAB) and minimum RL value are 5.4 GHz (d = 1.8 mm) and −36.1 dB (5.9 GHz, 4.0 mm), respectively. In particular, its specific EABs (EAB per unit thickness) in different bands are superior to those of most microwave absorbing materials with similar chemical composition. These results demonstrate that this dual-pathway optimization will open a new avenue to enhance microwave absorption performance of core–shell composites in the future.

Polycrystalline ZSM-5@Beta core–shell composites fabricated by a seed-directed approach: A catalyst to boosting light olefin production by ordered hierarchical cracking

Featuring engineerable reaction pathway, ordered hierarchical cracking over core–shell structured zeolites (core@shell) plays a pivotal role in achieving the high-efficient conversion of low-value oil fractions into important petrochemical building blocks such as ethylene and propylene. However, the synthesis of core@shell zeolite composites with specific desirable textures is technically challenging. Herein, a novel embryo seed-breeding (ESB) approach was developed to synthesize polycrystalline ZSM-5@Beta core–shell composites (pZ@B) for boosted light olefin production. For the first time, pZ@B composites composed of a polycrystalline ZSM-5 core and a submicron-sized Beta shell was reported, which shows enhanced inner-diffusion properties and improved hydrothermal stabilities than that of conventional ZSM-5@Beta composites. In pZ@B-catalyzed reations, bulky molecules undergone a preliminary cracking into intermediate products within the Beta shell, followed by the direct diffusion into the micropores of the ZSM-5 core where they could be cracked selectively into ethylene and propylene. Compared with physically mixed zeolites and hierarchical ZSM-5, pZ@B composites showed the highest conversion and yield of ethylene and propylene in the cracking reaction of both decalin and practical industrial heavy oil. The superior catalytic activity of pZ@B can be attributed to the high accessibility of acid sites and the ordered hierarchical cracking space derived from the core–shell structure.

Microstructure and Mechanical Properties of Core-Shell B4C-Reinforced Ti Matrix Composites.

Composite material uses ceramic reinforcement to add to the metal matrix to obtain higher material properties. Structural design is an important direction of composite research. The reinforcement distribution of the core-shell structure has the unique advantages of strong continuity and uniform stress distribution. In this paper, a method of preparing boron carbide (B4C)-coated titanium (Ti) powder particles by ball milling and preparing core-shell B4C-reinforced Ti matrix composites by Spark Plasma Sintering was proposed. It can be seen that B4C coated on the surface of the spherical Ti powder to form a shell structure, and B4C had a certain continuity. Through X-ray diffraction characterization, it was found that B4C reacted with Ti to form layered phases of titanium boride (TiB) and titanium carbide (TiC). The compressive strength of the composite reached 1529.1 MPa, while maintaining a compressive strain rate of 5%. At the same time, conductivity and thermal conductivity were also characterized. The preparation process of the core-shell structure composites proposed in this paper has high feasibility and universality, and it is expected to be applied to other ceramic reinforcements. This result provides a reference for the design, preparation and performance research of core-shell composite materials.

Chiral Covalent-Organic Framework MDI-β-CD-Modified COF@SiO2 Core-Shell Composite for HPLC Enantioseparation.

The chiral covalent-organic framework (CCOF) is a new kind of chiral porous material, which has been broadly applied in many fields owing to its high porosity, regular pores, and structural adjustability. However, conventional CCOF particles have the characteristics of irregular morphology and inhomogeneous particle size distribution, which lead to difficulties in fabricating chromatographic columns and high column backpressure when the pure CCOFs particles are directly used as the HPLC stationary phases. Herein, we used an in situ growth strategy to prepare core-shell composite by immobilizing MDI-β-CD-modified COF on the surface of SiO2-NH2. The synthesized MDI-β-CD-modified COF@SiO2 was utilized as a novel chiral stationary phase (CSP) to explore its enantiomeric-separation performance in HPLC. The separation of racemates and positional isomers on MDI-β-CD-modified COF@SiO2-packed column (column A) utilizing n-hexane/isopropanol as the mobile phase was investigated. The results demonstrated that column A displayed remarkable separation ability for racemic compounds and positional isomers with good reproducibility and stability. By comparing the MDI-β-CD-modified COF@SiO2-packed column (column A) with commercial Chiralpak AD-H column and the previously reported β-CD-COF@SiO2-packed column (column B), the chiral recognition ability of column A can be complementary to that of Chiralpak AD-H column and column B. The relative standard deviations (RSDs) of the retention time and peak area for the separation of 1,2-bis(4-fluorophenyl)-2-hydroxyethanone were 0.28% and 0.79%, respectively. Hence, the synthesis of CCOFs@SiO2 core-shell composites as the CSPs for chromatographic separation has significant research potential and application prospects.

Metal-Enhanced Fluorescence for Alpha-Fetoprotein Detection and for SERS Using Hybrid Nanoparticles of Magnetic Cluster Core—Plasmonic Shell Composite

We demonstrated that the hybrid core–shell nanostructure of Fe3O4 (core) and gold (shell) could be a good substrate candidate both for metal-enhanced fluorescence (MEF) and surface-enhanced Raman spectroscopy (SERS). The magnetic properties of the core material could provide functionalities such as the magnetically induced aggregation/distribution of nanostructures to increase the hot-spot density, while the nano-thickness gold shell allows for the plasmonic enhancement of both fluorescence and SERS. The gold-capped magnetic (Fe3O4) nanoparticles (GMPs) were facilely synthesized using a newly developed chemical method. The relative molar ratio of the constituent materials of the core–shell composite was optimized for tuning the plasmonic resonance wavelengths for MEF and SERS. We employed GMP-based MEF to detect alpha-fetoprotein (AFP), with concentrations ranging from 0.05 to 1000 ng/mL, and obtained a limit of detection (LOD) as low as 3.8 × 10−4 ng/mL. The signal enhancement factor (EF) in the GMP-based MEF was 1.5 at maximum. In addition, the GMPs were used in SERS to detect rhodamine B (RhB). Its LOD was 3.5 × 10−12 M, and the EF was estimated to be about 2 × 108. The hybrid core–shell nanoparticles could find potential applications in diagnostic assays based on MEF and SERS in various fields such as food verification, environmental testing/monitoring, and disease diagnosis.

High-performance microwave absorption by optimizing hydrothermal synthesis of BaFe12O19@MnO2 core-shell composites.

Stealth technology advances in radar-absorbing materials (RAMs) continue to grow rapidly. Barium hexaferrite is the best candidate for RAMs applications. Manganese dioxide (MnO2) is a transition metal with high dielectric loss and can be used as a booster for changing polarization and reducing reflection loss. The advantages of BaFe12O19 and MnO2 can be combined in a core-shell BaFe12O19@MnO2 composite to improve the material's performance. MnO2 composition, temperature, hydrothermal holding time, and sample thickness all have an impact on the core-shell structure. In this study, a core-shell BaFe12O19@MnO2 composite is synthesized in two stages: molten salt synthesis to produce BaFe12O19 as the core and hydrothermal synthesis to synthesize MnO2 as the shell. In the hydrothermal synthesis, BaFe12O19 and KMnO4 were mixed in deionized water using different mass ratios of BaFe12O19 to KMnO4 (1 : 0.25, 1 : 0.5, 1 : 0.75, and 1 : 1). The main goal of the analysis was to figure out how well the hydrothermal synthesis method worked at different temperatures (140 °C, 160 °C, and 180 °C) and holding times (9 h, 12 h, and 15 h). The composite material was subjected to characterization using a vector network analyzer, specifically at thicknesses of 1.5 mm, 2 mm, 2.5 mm, and 3 mm. The hydrothermal temperature and composition ratio of BaFe12O19 : MnO2 are the most influential parameters in reducing reflection loss. Accurate control of the parameters makes a BaFe12O19@MnO2 core-shell composite structure with a lot of sheets. The structure is capable of absorbing 99.99% of electromagnetic waves up to a sample thickness of 1.5 mm. The novelty of this study is its ability to achieve maximal absorptions on a sample with minimal thickness through precise parametric control. This characteristic makes it highly suitable for practical applications, such as performing as an anti-radar coating material. BaFe12O19@MnO2 demonstrates performance as a reliable electromagnetic wave absorber material with simple fabrication, producing absorption at C and X band frequencies.

An effective strategy for promoting charge separation by integrating heterojunctions and multiple homojunctions in TiO2 nanorods to enhance photoelectrochemical oxygen evolution.

It is important to achieve high photoelectrochemical (PEC) oxygen evolution performance in titanium oxide (TiO2) via the separation and transportation of photogenerated carriers. Herein, three-dimensional (3D) TiO2 nanorod arrays growing on flexible carbon cloth (CC) were decorated with graphitic carbon nitride (g-C3N4) to yield a 3D g-C3N4/TiO2/CC heterojunction composite (TCN). The photocurrent density of TCN is 10.6 times that of the bare TiO2 nanorod arrays, which can be attributed to the promoted separation and transportation of photogenerated carriers by the heterojunction. Then, a simple rapid cooling and heating (RCH) treatment was creatively introduced to form a gradient Ti3+ self-doping TiO2 multiple homojunction (GTSD-TiO2) in the bulk during the hydrothermal growth of the TiO2 nanorod array. This can further facilitate the separation and transportation of carriers in the bulk owing to the formation of a built-in electric field. The GTSD-TiO2 was decorated with g-C3N4 to form a core-shell heterojunction composite (GTSD-TCN). Notably, the photocurrent density of the GTSD-TCN core-shell heterojunction reached 1.23mAcm-2 at 1.23V (vs reversible hydrogen electrode (RHE)) under air mass (AM) 1.5 G illumination without the use of hole scavengers or cocatalysts; this was twice the photocurrent density of the TCN heterojunction (0.64mAcm-2) and is one of the best values obtained from the previously reported TiO2 and g-C3N4 heterojunction. This performance may be ascribed to the enhanced charge separation and transportation efficiency of the heterojunction after the RCH treatment; the efficiency rises from 51% (TCN) to 71% (GTSD-TCN). We believe that the RCH treatment is a highly promising method towards fabricating unique multiple homojunctions by gradient self-doping. This simple and novel design provides a new route for the preparation of high-performance PEC photoelectrodes.

Microstructure, properties and toughening mechanisms of MoSi2@ZrO2 core shell composites prepared by spark plasma sintering

Microstructure, properties and toughening mechanisms of MoSi2@ZrO2 core shell composites prepared by spark plasma sintering

An ultra-sensitive NH3 gas sensor enabled by an ion-in-conjugated polycroconaine/Ti3C2Tx core-shell composite.

MXenes are emerging sensing materials due to their metallic conductivity and rich surface chemistry for analytes; they, however, suffer from poor stability. Incorporation with functional polymers can largely prevent the performance decay and enhance the sensing performance. Herein, we demonstrate a core-shell composite, Ti3C2Tx@croconaine (poly(1,5-diaminonaphthalene-croconaine), PDAC) prepared by a facile in situ polymerization reaction, suitable for NH3 detection. Compared to pristine Ti3C2Tx, the sensor made of a Ti3C2Tx-polycroconaine composite exhibits a significantly enhanced sensitivity of 2.8% ppm-1 and an estimated achievable limit of detection of 50 ppb. The improved sensing performance could be attributed to the presence of PDAC facilitating the adsorption of NH3 and changing the tunneling conductivity between Ti3C2Tx domains. Density functional theory (DFT) calculations reveal that the adsorption energy of NH3 on PDAC is the highest among the tested gases, which supports the selectivity of the sensor to this analyte. Benefiting from the protection conferred by the PDAC shell, the composite has a reliable operation period of at least 40 days. In addition, we demonstrated a flexible paper-based sensor of the Ti3C2Tx@PDAC composite, without attenuated performance upon mechanical deformation. This work proposed a novel mechanism and a feasible methodology to synthesize MXene-polymer composites with improved sensitivity and stability for chemical sensing.

Pore-Rich Cellulose-Derived Carbon Fiber@Graphene Core-Shell Composites for Electromagnetic Interference Shielding.

Because of serious electromagnetic pollution caused by the widespread use of radio frequency equipment, the study of electromagnetic interference (EMI) shielding materials has been a long-standing topic. Carbon fiber and graphene composites have great potential as EMI shielding materials due to their unique microstructure and electrical conductivity. In this work, a novel kind of core-shell composite is fabricated based on the pore-rich pine needles-derived carbon fibers (coded as PNCFs) core and the graphene shell. The pore-rich PNCFs are created by KOH activation, and the integration between the pore-rich PNCFs and the graphene relies on a plasma-enhanced chemical vapor deposition (PECVD) method. The conductivity of the pore-rich PNCFs@graphene core-shell composite reaches 4.97 S cm−1, and the composite has an excellent EMI shielding effectiveness (SE > 70 dB over X-band (8.2−12.4 GHz)) and achieves a maximum value of ~77 dB at 10.4 GHz, which is higher than many biobased EMI shielding materials in the recent literature. By calculation and comparison, the large absorption loss (accounting for 90.8% of total loss) contributes to reducing secondary radiation, which is quite beneficial for stealth uses. Thus, this work demonstrates a promising design method for the preparation of green high-performance composites for EMI shielding and stealth applications (such as warcrafts, missiles, and stealth wears).

A novel γ‒BMO@BMWO Z‒Scheme heterojunction for promotion photocatalytic performance: Nanofibers thin film by Co‒axial‒electrospun

Bismuth molybdate has three phases α-Bi2MoO6, β-Bi2Mo2O9, and γ- Bi2Mo3O12, each of which has unique properties that distinguish them from each other. Among them, Bi2MoO6 and Bi2Mo3O12 have the most stability. In this research, γ-Bi2MoO6@Bi2Mo2.66W0.34O12 core‒shell nanofibers were deposited on the stainless steel mesh as effective and low‒cost substrate. The co‒axial electrospinning as a simple method was applied to form nanofibers on the substrate. Both of the abovementioned bismuth molybdates contents include different crystal facets, controlling the Red‒Ox properties. α-Bi2MoO6 possesses the vast numbers of oxygen vacancies in Mo–O bonding makes the oxidant {100} crystal facet. Likewise, γ‒Bi2Mo2.66W0.34O12 contains brittle facet of {010} with high concentration of Oxygen vacancies resulted in oxidative capability of the core‒shell composite. The obtained data indicated the key role of OH radical through photocatalytic reactions and a new heterojunction having direct Z‒scheme standing.

Plasmonic nanoresonator distributions for uniform energy deposition in active targets

Active targets implanted with core-shell-composition (CS) and nanorod-shaped (NR) plasmonic nanoresonators and doped with dyes were designed to ensure uniform energy deposition during illumination by two-counter propagating short laser pulses. The near-field enhancement, optical responses, and cross-sections were mapped above the concentration-Epump parameter-plane to inspect two different regions (I and II) with the potential to improve light-matter interaction phenomena. The distribution of steady-state absorption, as well as of the power-loss and power-loss density integrated until the complete overlap of the two short pulses was determined. The uniform distribution was adjusted to constrain standard deviations of the integrated power-loss distributions in the order of ∼10%. Dye doping of target-I/II implanted with uniform CS (NR) nanoresonator distributions results in larger absorption with increased standard deviation, larger power-loss, and power-loss density with decreased (decreased / increased) standard deviation. The adjustment allows larger absorption in CS-II and larger power-loss and power-loss density in CS-implanted targets, smaller standard deviation in targets-I for absorption, and in all targets for power-loss and its density. Larger dye concentration makes it possible to achieve larger absorption (except in adjusted NR-II), larger power-loss and power-loss density in all CS and in adjusted NR distributions, with decreased standard deviation in CS-implanted targets for all quantities and in NR-implanted targets for absorption. CS implantation results in larger absorption with a larger standard deviation, moreover allows larger power-loss in adjusted distributions and smaller standard deviation in power-loss quantities for larger concentration in both distributions and the same standard deviation for smaller concentration in adjusted distribution. Based on these results, adjusted CS distributions in targets doped with a dye of higher concentration are proposed.

Core-Shell Engineering of Conductive Fillers toward Enhanced Dielectric Properties: A Universal Polarization Mechanism in Polymer Conductor Composites.

Flexible dielectric and electronic materials with high dielectric constant (k) and low loss are constantly pursued. Encapsulation of conductive fillers with insulating shells represents a promising approach, and has attracted substantial research efforts. However, progress is greatly impeded due to the lack of a fundamental understanding of the polarization mechanism. In this work, a series of core-shell polymer composites is studied, and the correlation between macroscopic dielectric properties (across entire composites) and microscopic polarization (around single fillers) is investigated. It is revealed that the polarization in polymer conductor composites is determined by electron transport across multiple neighboring conductive fillers-a domain-type polarization. The formation of a core-shell filler structure affects the dielectric properties of tpolymer composites by essentially modifying the filler-cluster size. Based on this understanding, a novel percolative composite is prepared with higher-than-normal filler concentration and optimized shell's electrical resistivity. The developed composite shows both high-k due to enlarged cluster size and low loss due to restrained charge transport simultaneously, which cannot be achieved in traditional percolative composites or via simple core-shell filler design. The revealed polarization mechanism and the optimization strategy for core-shell fillers provide critical guidance and a new paradigm, for developing advanced polymer dielectrics with promising property sets.

Fabrication of robust Fe2O3@NiCo2O4 core-shell composite with spikey surface for high-performance asymmetric solid-state supercapacitor

The need for a cost-effective and efficient energy storage system instigates researchers to develop emerging electrode materials for energy storage devices. The α-Fe2O3-based electrode material for supercapacitor application has received interest due to its good electrochemical performance, high mechanical strength, corrosion resistance, low cost, and abundant availability. This work develops a cost-effective, robust Fe2O3@NiCo2O4 core-shell composite with spikey surface via a facile hydrothermal strategy for high-performance electrode material for supercapacitors. The spikes of Fe2O3 are developed on NiCo2O4 to collaborate in a more accessible surface area, with robust morphological stability throughout electrochemical performances. The Fe2O3@NiCo2O4 core-shell composite exhibits a high specific capacity of 364 C g−1 at the scan rate of 5 mV s−1 and 81% cycling stability up to 10,000 successive charge-discharge cycles at the current density of 15 A g−1. Moreover, an asymmetric solid-state supercapacitor (ASSC) device was fabricated using Fe2O3@NiCo2O4 composite as a positive electrode and commercially purchased activated carbon as a negative electrode assembled via PVA/KOH gel electrolyte. The fabricated device offers a significant energy density of 31.7 W h Kg−1 at a power density of 700 W Kg−1. The ASSC exhibits excellent capacitance retention of 90% with ultra-high coulombic efficiency of 99.7% up to 10,000 GCD cycles. The ASSC can illuminate the red and yellow LED light. This work indicates that a robust Fe2O3@NiCo2O4 core-shell composite can be an economic strategy for fabricating high-performance practical supercapacitor applications.

Tunable shell thickness of Fe-N@SiO2 nanoparticles for strong and stable microwave absorption properties with enhanced oxidation resistance

Core-shell composites Fe-N @ SiO 2 with 500 nm average sizes of cores have been successfully prepared by a combination of hydrothermal, gaseous nitriding and Stöber methods. The Fe-N cores are composed of Fe 4 N as major phase and FeN as minority. The thickness of SiO 2 shell increases continuously with increase of the tetraethyl orthosilicate weight. Relative to the natures of Fe-N, Fe-N @ SiO 2 composites show slightly weaker ferromagnetic capacity, but much higher oxidation resistance. The Fe-N sample exhibits extremely high relative permittivity. With filling loading of 50 wt%, it has a moderate microwave absorption performance with a maximum reflection loss about −10 dB. Owing to low conductivity, non-magnetic property and superior anti-oxidation ability of the SiO 2 shell, the core-shell structures have considerably degraded permittivity, and nearly unchanged permeability. These changes bring a much better impedance matching between the permittivity and permeability, and further bring a greatly enhanced microwave absorption performance. All of the Fe-N @ SiO 2 composites have strong absorption abilities. They are quite stable with variation of shell thickness. The composite of 52 nm shell thickness has maximum reflection loss of −23.1 dB at 17.2 GHz, and effective absorption bandwidth (<−10 dB) of 2.4 GHz with absorber thickness 5.5 mm. The present study gives an insight on the roles of silica material influencing the iron-based absorber’s absorption ability. • Fe-N @ SiO 2 nanoparticles with tunable shell thickness were synthesized. • Ferromagnetic Fe-N @ SiO 2 composites have good oxidation resistance. • Core-shell absorbers exhibit strong and stable absorption performance. • Mechanism for SiO 2 modification of absorption performance was revealed.

TiO2/core-shell structured carbon support materials derived from hydrothermal carbonization of waste masks biomass: A green photocatalyst

• The surface area of the core-shell structured carbon was 87.20 m 2 g -1 . • MC-TiO 2 increased the light absorption capacity and extended the electron-hole pair recombination time. • MC-TiO 2 exhibited the highest photodegradation yield among all photocatalysts. • The waste masks problem, one of the negative effects of COVID-19, was turned into an advantage in this study. Surgical masks have become mandatory to protect against the COVID-19 epidemic. For this reason, the amount of waste masks has also reached severe dimensions. Turning these waste masks into functional materials (MC) in a green synthesis method is critical. In this study, carbon material from waste masks was synthesized by the hydrothermal carbonization method (HTC) and was used to increase the photocatalytic activity of TiO 2 . In addition, TiO 2 nanoparticles were successfully synthesized by the solvothermal method. Thermo-gravimetric analysis (TGA), scanning-electron microscope (SEM), X-ray diffraction (XRD), Fourier transform- infrared spectroscopy (FT-IR), energy dispersive X-ray (EDX), transmission-electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), electrochemical-impedance spectroscopy (EIS) and Brunauer–Emmett–Teller (BET) analyzes were performed to illuminate the photocatalytic properties of the MC-TiO 2 photocatalyst. In this sense, the functionality of the shell-core skeleton-based new generation carbon material was also investigated. The photocatalytic activity of the green type of photocatalyst was detected by comparing methylene blue (MB) and phenol photodegradation rates. In photocatalytic degradation experiments, both UV-A effect and visible light effect were examined. New type of photocatalyst an exhibited excellent photocatalytic effect. Superior photodegradation capacity may be referred as to the core-shell composition and functional groups of the effective carbon support material synthesized by the HTC method. In particular, the photocatalytic effect of the novel carbon support material is discussed in-depth with the proposed mechanism. With the present study, we aimed to bring a green perspective to the photocatalytic studies in the literature.

Molecular Dynamics and Structure of Poly(Methyl Methacrylate) Chains Grafted from Barium Titanate Nanoparticles.

Core−shell nanocomposites comprising barium titanate, BaTiO3 (BTO), and poly(methyl methacrylate) (PMMA) chains grafted from its surface with varied grafting densities were prepared. BTO nanocrystals are high-k inorganic materials, and the obtained nanocomposites exhibit enhanced dielectric permittivity, as compared to neat PMMA, and a relatively low level of loss tangent in a wide range of frequencies. The impact of the molecular dynamics, structure, and interactions of the BTO surface on the polymer chains was investigated. The nanocomposites were characterized by broadband dielectric and vibrational spectroscopies (IR and Raman), transmission electron microscopy, differential scanning calorimetry, and nuclear magnetic resonance. The presence of ceramic nanoparticles in core–shell composites slowed down the segmental dynamic of PMMA chains, increased glass transition temperature, and concurrently increased the thermal stability of the organic part. It was also evidenced that, in addition to segmental dynamics, local β relaxation was affected. The grafting density influenced the self-organization and interactions within the PMMA phase, affecting the organization on a smaller size scale of polymeric chains. This was explained by the interaction of the exposed surface of nanoparticles with polymer chains.

Ultrasmall Copper Nanoclusters in Zirconium Metal‐Organic Frameworks for the Photoreduction of CO2

AbstractEncapsulating ultrasmall Cu nanoparticles inside Zr‐MOFs to form core–shell architecture is very challenging but of interest for CO2reduction. We report for the first time the incorporation of ultrasmall Cu NCs into a series of benchmark Zr‐MOFs, without Cu NCs aggregation, via a scalable room temperature fabrication approach. The Cu NCs@MOFs core–shell composites show much enhanced reactivity in comparison to the Cu NCs confined in the pore of MOFs, regardless of their very similar intrinsic properties at the atomic level. Moreover, introducing polar groups on the MOF structure can further improve both the catalytic reactivity and selectivity. Mechanistic investigation reveals that the CuIsites located at the interface between Cu NCs and support serve as the active sites and efficiently catalyze CO2photoreduction. This synergetic effect may pave the way for the design of low‐cost and efficient catalysts for CO2photoreduction into high‐value chemical feedstock.

Ultrasmall Copper Nanoclusters in Zirconium Metal-Organic Frameworks for the Photoreduction of CO2.

Encapsulating ultrasmall Cu nanoparticles inside Zr-MOFs to form core-shell architecture is very challenging but of interest for CO2 reduction. We report for the first time the incorporation of ultrasmall Cu NCs into a series of benchmark Zr-MOFs, without Cu NCs aggregation, via a scalable room temperature fabrication approach. The Cu NCs@MOFs core-shell composites show much enhanced reactivity in comparison to the Cu NCs confined in the pore of MOFs, regardless of their very similar intrinsic properties at the atomic level. Moreover, introducing polar groups on the MOF structure can further improve both the catalytic reactivity and selectivity. Mechanistic investigation reveals that the CuI sites located at the interface between Cu NCs and support serve as the active sites and efficiently catalyze CO2 photoreduction. This synergetic effect may pave the way for the design of low-cost and efficient catalysts for CO2 photoreduction into high-value chemical feedstock.