Fabrication and Properties of Carbon- Encapsulated Cobalt Nanoparticles over NaCl by CVD

Carbon-encapsulated cobalt (Co@C) nanoparticles, with a tunable structure, were synthesized by chemical vapor deposition using Co nanoparticles as the catalyst and supported on a water-soluble substrate (sodium chloride), which was easily removed by washing and centrifugation. The influences of growth temperature and time on the structure and magnetic properties of the Co@C nanoparticles were systematically investigated. For different growth temperatures, the magnetic Co nanoparticles were encapsulated by different types of carbon layers, including amorphous carbon layers, graphitic layers, and carbon nanofibers. This inferred a close relationship between the structure of the carbon-encapsulated metal nanoparticles and the growth temperature. At a fixed growth temperature of 400 °C, prolonged growth time caused an increase in thickness of the carbon layers. The magnetic characterization indicated that the magnetic properties of the obtained Co@C nanoparticles depend not only on the graphitization but also on the thickness of the encapsulated carbon layer, which were easily controlled by the growth temperatures and times. Optimization of the synthesis process allowed achieving relatively high coercivity of the synthesized Co@C nanoparticles and enhancement of its ferromagnetic properties, which make this system promising as a magnetic material, particularly for high-density magnetic recording applications

A Novel Hierarchically Porous Polypyrrole Sphere Modified Separator for Lithium-Sulfur Batteries

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6723804/The commercialization of Lithium-sulfur batteries was limited by the polysulfide shuttle effect, and modifying the routine separator was an effective method to solve this problem. In this work, a novel hierarchically porous polypyrrole sphere (PPS) was successfully prepared by using silica as hard-templates. As-prepared PPS was slurry-coated on the separator, which could reduce the polarization phenomenon of the sulfur cathode, and efficiently immobilize polysulfides. As expected, high sulfur utilization was achieved by suppressing the shuttle effect. When tested in the lithium-sulfur battery, it exhibited a high capacity of 855 mAh·g−1 after 100 cycles at 0.2 C, and delivered a reversible capacity of 507 mAh·g−1 at 3 C, showing excellent electrochemical performance

Electrophoretic deposition and laser cladding of bioglass coating on Ti

Bioglass coatings derived from electrophoretic deposition method were fused on Ti surface by laser cladding process using a continuous CO laser. The specimens were studied by field-emission scanning electron microscopy, X-ray diffraction and bonding tests. Titanium oxide layer with hierarchical structures consisting of submicron rows of leaf-like embossments and nano-pores was obtained by combining acid etching and anodization processes, which increased the surface roughness of Ti. When heat-treatment temperature was 700 °C and high, CaSiO phase began to crystallize from the bioglass matrix and the crystallinity reached its maximum at 700 °C. During the electrophoretic deposition process, porous bioglass coatings composed of bioglass particles and fibers were deposited on Ti surface. Bioglass coatings with similar hierarchical structure containing submillimeter bioglass beads and microfibers were synthesized on Ti surface by laser fusion. There are no obvious microcracks at the interface of the Ti-coating, which revealed the good bonding between Ti-porcelain. With the laser scanning distance decreased, the bond strength increased accordingly. After only one day immersion in SBF, calcium phosphate began to precipitate on the bioglass coating's surfaces. The thickness of the calcium phosphate precipitation and the amount of microparticles increased with immersion time

Synthesis and Characterization of Flower-like Carbon-encapsulated Fe-C Nanoparticles for Application as Adsorbing Material

Carbon-encapsulated Fe-C (Fe-C@C) nanoparticles with a divergently flower-like morphology were successfully synthesized for application as an adsorbing material by using freeze-drying and chemical vapor deposition (CVD) methods. The Fe metallic source was first loaded onto a sodium chloride (NaCl) supporter via freeze-drying to obtain the Fe/NaCl composite powder. Then, Fe-C@C nanoparticles were synthesized in the temperature range of 300–450 °C via CVD of acetylene in the Fe/NaCl composite powder using Fe nanoparticles as catalysts and NaCl as supporters. Because the NaCl supporter is water-soluble, the synthesized Fe-C@C nanoparticles were easy to purify, and a high purity was obtained by simple washing and centrifugation. The optimal Fe-C@C nanoparticles, synthesized at 400 °C, possessed a unique divergently flower-like structure and a high specific surface area of 169.4 m2/g that can provide more adsorption sites for contaminants. Adsorption experiments showed that the flower-like Fe-C@C adsorbent exhibited high adsorption capacity (90.14 mg/g) and fast removal of methylene blue (MB). Moreover, the magnetic properties of the nanoparticles, with saturation magnetization of 36.544 emu/g, facilitated their magnetic separation from wastewater. Therefore, the novel flower-like Fe-C@C nanoparticles with integrated adsorptive and magnetic properties have the potential to be an effective adsorbent in dye wastewater treatment

Biocompatibility of the micro-patterned NiTi surface produced by femtosecond laser

Biocompatibility of the micro-patterned NiTi surface produced by femtosecond laser (FSL) was studied in this work. The surface characteristics of the laser treated NiTi alloys were investigated by scanning electron microscopy (SEM), atom force microscopy (AFM), X-ray diffractometry (XRD) and X-ray photoelectron spectrum (XPS). The biocompatibility was evaluated by in vitro cell culture test. The results showed that, grooves, ripples, which covered by nanoparticles were formed on the sample surfaces, and the Ni/Ti ratio on the alloy surface increased with increasing laser energy. The crystal structure was not changed by laser treatment. However, the cell culture test proved that the micro-patterns induced by FSL were beneficial to improve the biocompatibility of NiTi alloys: the growth of osteoblasts oriented along the grooves, a large amount of synapses and filopodias were formed due to the ripples, holes and nanoparticles on the alloy surface, and the proliferation rate and alkaline phosphatase (ALP) content of cells were increased after FSL treatment. However, due to the toxicity of Ni ions on cell growth, the NiTi alloy surface should not be treated by laser fluence of more than 3.82 J/cm(2) to obtain the ideal biocompatibility. (C) 2012 Elsevier B. V. All rights reserved

Sol–gel synthesis of TiO2-modified nanocomposite coatings on titanium

Titanium dioxide nanoparticles-modified nanocomposite coatings were synthesized on titanium by sol–gel process. The specimens were studied by differential scanning calorimetry, transmission electron microscopy, field-emission scanning electron microscopy and bonding tests. TEM results showed that TiO2 nanoparticles were adhered and enwrapped in the hybrid sol matrixes to form aggregates of TiO2 nanoparticles. The size of the particle aggregates increased from about 160\ua0nm to above 500\ua0nm with the content of the TiO2 particles increasing from 45 to 60\ua0ma%. At the same time, the quantities of the microcracks on the coating surface gradually decreased. The solid phase content of the sols was increased by the addition of TiO2 nanoparticles, which avoided the formation of microcracks on the coatings surface. Compared to the uncoated group, the highest bonding strength improvement of about 24\ua0% was obtained at the TiO2 content of 60 ma%. Graphical Abstract: [Figure not available: see fulltext.

Femtosecond laser induced micropatterns and in-situ deposition of Ca/P phase and collagen on Ti surface

Micropatterns which can be controlled precisely were obtained on titanium (Ti) surface by femtosecond lasers (FSL) ablation. The in-situ deposition of bioactive calcium phosphate (Ca/P) phase and collagen hybrid was achieved on Ti surface to form filamentous structure combined with nanoparticles, during the FSL treatment. The amount of deposited Ca/P phase increased with the laser energy during the whole process. While for the deposited collagen amount, it increased with the rise of the laser energy initially, and then decreased with the increase of laser energy. The FSL induced micropatterns and in-situ deposition of Ca/P phase and collagen are expected to result in excellent bioactivity and biocompatibility of the Ti implant. (C) 2015 Elsevier B.V. All rights reserved