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Controllable Core–Shell BaTiO <sub/>3</sub> @Carbon Nanoparticle-Enabled P(VDF-TrFE) Composites: A Cost-Effective Approach to High-Performance Piezoelectric Nanogenerators
摘要： Piezoelectric nanogenerators (PENGs), as a promising solution to harvest mechanical energy from ambient environment, have attracted much attention over the past decade. Here, the core-shell structured BaTiO3@Carbon (BT@C) nanoparticles (NPs) were synthesized by simple surface-modifying method and then used to fabricate the efficient PENGs with poly [(vinylidene fluoride)-co-trifluoroethylene] (P(VDF-TrFE)). The carbon shell with the uniform thickness of 10-15nm can increase the content of polar β phase in P(VDF-TrFE), and significantly enhance the interfacial polarization between BT NPs and polymer matrix during poling process. Out of all compositions, 15wt% BT@C/ P(VDF-TrFE) PENG exhibited the optimal piezoelectric performance with an output voltage of ~17V and the maximum power of 14.3μW under bending-releasing mode. More importantly, the PENG can also efficiently harvest other types of mechanical energy from human activities and exhibits stable output after 1500 bending-releasing cycles. When the PENG was bent and beat by bicycle spokes, a peak voltage of 16V was generated, which can light up 12 white LEDs directly and charge the commercial capacitors. Our research provides a new strategy to fabricate flexible and efficient PENGs from nanoscale viewpoint, it can be hopefully applied in energy harvesting system and wearable electric sensors.
关键词： Core-shell structure,energy harvesting,Interfacial polarization,composite material,piezoelectric nanogenerator
更新于2025-09-12 10:27:22
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Controlled Detonation Synthesis of Nano Fe-based Oxides/ SiO2 Core-shell Composite Particles
摘要： Controlled detonation of emulsion Explosive and Hexogen (a kind of high explosive, for short, RDX) was performed to prepare Fe-based oxides/SiO2 nanoparticles. XRD (X-ray diffraction), TEM (Transmission electron microscope) and VSM (Vibrating sample magnetometer) experiments were performed to characterize and investigate the ingredients and phase structure of the granules, morphology, and distribution of the particles and the magnetism of the powders respectively. Results indicated that Fe/Urea complex detonation via emulsion explosives was advantageous to prepare Fe-based oxides/SiO2 core-shell powders, the inner FeO/Fe core was properly coated by a silica outer shell with the core size of around 50nm and shell thickness of around 5~10nm. And most of the raw detonation dust were converted into SiO2 coating Fe particles with the remained core-shell structure after proper thermal treatment. Raw powders obtained by RDX detonation presented weaker magnetism than that via emulsion explosives detonation, but which was substantially improved after thermal treatment.
关键词： Controlled detonation,Fe-based oxides/SiO2,Emulsion explosive,Core-shell Structure
更新于2025-09-12 10:27:22
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Solidification Behavior of YSZ@Ni Nanoparticles during Laser Cladding Process
摘要： In this study, yttria-stabilized zirconia (YSZ) nanoparticles with a core-shell structure (YSZ@Ni) were used to produce a YSZ/metal thermal barrier coating by the laser cladding process. The surface morphology, phase composition, and elemental distribution of the cladding layer were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive spectroscopy (EDS), respectively. Splashing of YSZ nanoparticles during the cladding process was reduced when they were encapsulated with nickel. It was found that primary phases of elliptically shaped YSZ and YSZ/(FeCr2O4) eutectic nanostructures formed in the center of the molten pool, whereas equiaxed YSZ crystals formed along the edges after the laser cladding. The results showed that aggregation of Ni was observed in the interlayer between the ceramic coating and the substrate. Ni-rich spheres were observed around the equiaxed YSZ crystals. Furthermore, the solidification behavior of YSZ@Ni core-shell nanoparticles was analyzed by studying the thermodynamics and kinetics.
关键词： laser cladding,YSZ@Ni nanoparticles,coating,core-shell structure,solidification behavior
更新于2025-09-12 10:27:22
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A Review on Improving the Quality of Perovskite Films in Perovskite Solar Cells via the Weak Forces Induced by Additives
摘要： It is a challenge to design intelligent thermal metamaterials due to the lack of suitable theories. Here we propose a kind of intelligent thermal metamaterials by investigating a core-shell structure, where both the core and shell have an anisotropic thermal conductivity. We solve Laplace’s equation for deriving the equivalent thermal conductivity of the core-shell structure. Amazingly, the solution gives two coupling relations of conductivity tensors between the core and the shell, which cause the whole core-shell structure to counterintuitively self-?x a constant isotropic conductivity even when the area or volume fraction of the core changes within the full range in two or three dimensions. The theoretical ?ndings on fraction-independent properties are in sharp contrast with those predicted by the well-known e?ective medium theories, and they are further con?rmed by our laboratory experiments and computer simulations. This work o?ers two coupling relations for designing intelligent thermal metamaterials, and they are not only helpful for thermal stabilization or camou?age/illusion, but they also o?er hints on how to achieve similar metamaterials in other ?elds.
关键词： Laplace’s equation,intelligent thermal metamaterials,core-shell structure,anisotropic thermal conductivity,self-fixing behavior
更新于2025-09-11 14:15:04
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Polydopamine-inspired Design and Synthesis of Visible-light-driven Ag NPs@C@elongated TiO2 NTs Core-shell Nanocomposites for Sustainable Hydrogen Generation
摘要： The primary challenge of photocatalytic hydrogen generation is to exploit a catalyst with good durability and low cost. Here, we designed a facile and efficient process of loading silver nanoparticles (Ag NPs) in situ on the core-shell nanocomposite of the elongated titanium dioxide nanotubes with carbon layer (C@TiO2 NTs) by polydopamine (PDA) without addition of any binder. The combination of C@TiO2 NTs with Ag NPs has excellent performance toward photocatalytic hydrogen production and degradation of rhodamine B (RhB) under visible light irradiation. The characterizations (SEM, TAM, XRD, XPS, etc.) showed that the carbon layer on nanotubes could conformably cover the whole of TiO2 NTs to form core-shell structure, which not only prevented Ag NPs from aggregating, but also acted as the electronic transport channel. Meanwhile, Ag NPs were uniformly distributed on the surface of C@TiO2 NTs. In conclusion, under the synergistic effect of Ag nanoparticles and outer-carbon layer, the utilization efficiency of visible light has been enhanced and the recombination of electrons/holes has been suppressed for Ag@C@TiO2 NTs nanocomposites. Therefore, the degradation efficiency of RhB and hydrogen generation rate is 2.5 times and 4.8 times as higher as pure TiO2 NTs, respectively. This work may provide fruitful experience for developing novel strategy into the design and fabrication of stable and highly active visible-light catalysts with noble metal modification toward sustainable hydrogen production in the energy filed.
关键词： elongated TiO2 nanotube,carbon shell,Ag nanoparticle,visible-light induced photo-catalyst,core-shell structure
更新于2025-09-10 09:29:36
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Enhanced dielectric, electromechanical and hydrophobic behaviors of core-shell AgNWs@SiO2/PDMS composites
摘要： This paper reports a feasible method to prepare polymeric nanocomposites with enhanced dielectric, electromechanical and hydrophobic performance by introducing the core-shell AgNWs@SiO2 filler into polydimethylsiloxane (PDMS). The homogenous core-shell AgNWs@SiO2 was firstly synthesized through a two-step sol-gel process. The thicknesses of AgNWs and SiO2 coating layer are approximately 70 nm and 20 nm, respectively. The dielectric constant is improved effectively due to enhanced interfacial polarization, while extremely low dielectric loss and conductivity are achieved by introducing the insulating SiO2 interlayer to moderate the internal surface area of core-shell nanowires and restrict the electron transfer between Ag nanowires. Typically, the PDMS nanocomposites with 20 wt% AgNWs@SiO2 have a dielectric constant of 6.7, nearly 2.7 times larger than that of pure PDMS, and remains a quite low loss of 0.02 at 1 kHz. Meanwhile, nanocomposites also show improved electromechanical and hydrophoic properties. Nanocomposites with 10 wt% AgNWs@SiO2 exhibit the highest electromechanical sensitivity (β=9.04), about 12.6 times higher than that of pure PDMS at 1 kHz. The static contact angle of nanocomposties with 20 wt% AgNWs@SiO2 reaches 129°. All the improved performances show great potential application for dielectric elastomer material and electrowetting devices.
关键词： Dielectric properties,Electromechanical properties,Core-shell structure,Interfacial polarization
更新于2025-09-10 09:29:36
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Bionic SiO2@Fc(COCH3)2 Core-Shell Nanostructure for Enhancing the Electrochromic Properties of Ferrocene
摘要： Although the properties of electrochromic materials (ECMs) have been enhanced using fabricated porous materials, the effect of materials porosity on such an enhancement remains unclear. Here, we report a novel ECMs with an adjustable pore hierarchy based on quasi-amorphous and ordered arrays of SiO2@Fc(COCH3)2. ECMs with different pore systems were generated by modifying Fc(COCH3)2 concentration and self-assembly temperature. The composition and core-shell structure of the SiO2@Fc(COCH3)2 nanospheres were confirmed through scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FT-IR) and EDX mapping. The influence of adjustable pore system on the electrochemical behavior was studied. Experimental results showed that the current density of the redox couple peaks of the quasi-amorphous porous SiO2@Fc(COCH3)2 films are considerably lower than those of the ordered porous films but are higher than those of the dense Fc(COCH3)2 films. At 550 nm, the transmittance variation of the quasi-amorphous porous SiO2@Fc(COCH3)2 film is 19 %, whereas that of the ordered porous film is 35 %. The coloration and bleaching times of the quasi-amorphous porous SiO2@Fc(COCH3)2 film are 17.1 s and 4.5 s, respectively, whereas those of the ordered porous film are only 16.5 s and 3.5 s, respectively. Furthermore, the porosities of the films are solved numerically by the finite-element method. For the ordered porous SiO2@Fc(COCH3)2 film, the porosity is 0.26, while the quasi-amorphous film became larger (0.31～ 0.41). This work is the first step in combining ferrocene derivative and colloidal crystal porous structures to develop a green, simple and efficient electrochromic process.
关键词： electrochromism,adjustable porosity,colloidal crystals,ferrocene derivatives,core-shell structure
更新于2025-09-09 09:28:46
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Effect of thickness of Cr layer on Ag cocatalyst surface for highly selective photocatalytic conversion of CO <sub/>2</sub> by H <sub/>2</sub> O
摘要： In this study, we developed a Ag–Cr core–shell-structured (Ag@Cr) cocatalyst that modified the surface of the Ga2O3 photocatalyst. Compared to results provided by modifications with Ag cocatalysts and M–Cr dual cocatalysts (M = Au, Cu, Pd, and Pt), this change significantly improved the formation rate of CO and selectivity toward CO evolution in the photocatalytic conversion of CO2 by the electron donor H2O. As a result of this modification, the Cr(OH)3?xH2O shell changed to Cr(OH)x(CO3)y during the photocatalytic conversion. Furthermore, the thickness of the Cr(OH)3?xH2O shell was found to influence the photocatalytic performance. More specifically, Cr(OH)3?xH2O shells that were too thick or too thin were not beneficial to the CO evolution and suppression of H2 evolution. Notably, the highest photocatalytic activity (525.3 μmol h?1), selectivity toward CO evolution (85.2 %), and turnover number of CO to Ag (167) was achieved over 0.25 mol% (Ag@Cr)/Ga2O3. In addition to Ga2O3, the Ag@Cr cocatalyst modification strategy can also be applied to other photocatalyst materials such as NaTaO3, ZnGa2O4, and ZnGa2O4/Ga2O3 for the highly effective photocatalytic conversion of CO2 to CO when using H2O as an electron donor.
关键词： carbon dioxide,chromium hydroxide,Photocatalysis,core–shell structure,Ag cocatalyst
更新于2025-09-09 09:28:46
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Poly(vinylidene fluoride)-based nanocomposite employing oriented Bi2S3 nanorods with double-shell structure for high dielectric performance and loss suppression
摘要： For polymer-based nanocomposites, designing the nanostructures of fillers, their distribution inside matrix as well as interfaces with the polymer is of crucial importance to achieve high dielectric performances. One-dimensional semiconductor Bi2S3 nanorods coated with homogeneous SiO2 and polydopamine (PDA) double shell layers were imported into the poly(vinylidene fluoride) (PVDF) with parallel arrangement via uniaxial stretching to form Bi2S3@SiO2@PDA/PVDF nanocomposite. The dielectric performances of oriented Bi2S3@SiO2@PDA/PVDF were studied in comparison with its counterparts employing Bi2S3 fillers without shell layers or alignment. A microcapacitor model was used to accurately estimate the dielectric constant along perpendicular direction. Coating conductive Bi2S3 nanorods with insulating SiO2@PDA double layer remarkably reduces the dielectric loss of the nanocomposite, while alignment of one-dimensional Bi2S3@SiO2@PDA nanorods endows electrical properties anisotropy, which was understood from J-V curves measured along two directions and moreover, via three-dimensional finite element analysis, unambiguously revealing the effects of aligned core-shell structured fillers on local electric field and current density distribution. This study provides a promising and facile approach for designing high performance dielectrics.
关键词： Polymer-matrix composites,Anisotropy,Numerical simulation,Dielectric performances,Ordered structure,Core-shell structure
更新于2025-09-04 15:30:14
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[IEEE 2018 XXIIIrd International Seminar/Workshop on Direct and Inverse Problems of Electromagnetic and Acoustic Wave Theory (DIPED) - Tbilisi, Georgia (2018.9.24-2018.9.27)] 2018 XXIIIrd International Seminar/Workshop on Direct and Inverse Problems of Electromagnetic and Acoustic Wave Theory (DIPED) - Magnetometry and NMR Study of Carbon Nanopowders Doped with Cobalt Nanoclusters and Self-assembly of their Polymer Nanocomposites under Magnetic Field
摘要： The RF resonant magnetometry and NMR studies were carried out on carbon nanoparticles doped with magnetic cobalt clusters, which were synthesized by a technology combining of the hydrocarbon vapor pyrolysis and the chemical vapor deposition (CVD) process in a horizontal continuous reactor. The RF resonant magnetometry data show that the obtained carbon cobalt nanopowders are superparamagnetic at room temperatures and ferromagnetic at liquid nitrogen temperatures. The NMR study with the excitation by additional magnetic video-pulses of nanopowders obtained by using different hydrocarbons pyrolysis made it possible a fast assessment of their magnetic phase and hardness properties. The simple non-contact RF resonant magnetometry study of self-assembling processes in carbon cobalt polymer composite films synthesized using these nanopowders was made also.
关键词： magnetic nanoclusters,carbon nanopowder,core-shell structure,self-assembly,NMR,cobalt
更新于2025-09-04 15:30:14