Nanocable catalysts MTe(M=Pt,PtCu)@UIO-67 for CO2 conversion

Zr-based metal–organic framework nanocable catalysts comprising MTe(M=Pt,PtCu)@UIO-67 resembling"sugarcoated haws on a stick"were assembled.Ultrathin Te nanowires with diameters of about 8.48 nm served as a sacrificial template for the epitaxial growth of an outer M(Pt or PtCu)to obtain cable cores comprising MTe nanowires with good dispersity,which were then successfully encapsulated in the center of a monodisperse MTe@UIO-67 cable nanostructured catalyst.Transmission electron microscopy(TEM),scanning electron microscopy(SEM),powder X-ray diffraction(XRD)and energy dispersive X-ray(EDX)element mapping were used to investigate the morphology,structure and composition of the nanocable catalysts.Six types of catalysts were synthesized,and all of the catalysts demonstrated superior product selectivity to CO for reverse water-gas shift(RWGS)reaction.Especially,the morphology and dispersion of PtCuTe@UIO-67 nanocable catalyst can be maintained to some extent after catalysis at high temperature,and PtTe@UIO-67 catalyzed CO2 conversion was achieved with 99.86%CO selectivity.

Template Synthesis and Characterization of Cu2O/TiO2 Coaxial Nanocable for Photocatalysis

Coaxial nanocable consisted of p-type Cu2O nanowires and n-type TiO2 nanotubes arrays was prepared in the porous anodic aluminum oxide（AAO） template via the sol-gel method and subsequent electrodeposition method. X-ray diffraction analysis identified an anatase structure of the TiO2 nanotubes and cubic structure of the Cu2O nanowires. The obtained samples were also characterized by scanning electron microscopy（SEM）, transmission electron microscopy（TEM） and energy dispersive X-ray spectroscopy（EDS）. The diffrence of open circuit potential of the coaxial nanocable electrode was larger than that of the TiO2 nanotubes electrode under ultraviolet illumination, which means doping with Cu2O could improve the photovoltage effectively. Meanwhile, nanocable arrays exhibited a high activity for photodegrading Rhodamine B under Xe lamp irradiation and the photocatalysis degradation efficiency was up to 98.69% after degradation for 7 h. The enhanced photocatalytic activity could be attributed to the high migration efficiency of photoinduced electrons, which may suppress the charge recombination effectively.

Magnetic Fe_(2)P Nanowires and Fe_(2)P@C Core@Shell Nanocables

We report the synthesis of one-dimensional(1-D)magnetic Fe_(2)P nanowires and Fe_(2)P@C core@shell nanocables by the reactions of triphenylphosphine(PPh_(3))with Fe powder(particles)and ferrocene(Fe(C_(5)H_(5))_(2)),respectively,in vacuum-sealed ampoules at 380-400℃.The synthesis is based on chemical conversion of micrometer or nanometer sized Fe particles into Fe_(2)P via the extraction of phosphorus from liquid PPh_(3) at elevated temperatures.In order to control product diameters,a convenient sudden-temperature-rise strategy is employed,by means of which diameter-uniform Fe_(2)P@C nanocables are prepared from the molecular precursor Fe(C_(5)H_(5))2.In contrast,this strategy gives no obvious control over the diameters of the Fe_(2)P nanowires obtained using elemental Fe as iron precursor.The formation of 1-D Fe_(2)P nanostructures is ascribed to the cooperative effects of the kinetically induced anisotropic growth and the intrinsically anisotropic nature of hexagonal Fe_(2)P crystals.The resulting Fe_(2)P nanowires and Fe_(2)P@C nanocables display interesting ferromagnetic-paramagnetic transition behaviors with blocking temperatures of 230 and 268 K,respectively,significantly higher than the ferromagnetic transition temperature of bulk Fe_(2)P(TC=217 K).

Bioresorbable magnesium-based alloys containing strontium doped nanohydroxyapatite promotes bone healing in critical sized bone defect in rat femur shaft

Magnesium-based biomaterials have been in extensive research for orthopedic applications for decades due to their optimal mechanical features and osteopromotive nature;nevertheless,rapid degradation restricts their clinical applicability.In this study,pristine magnesium was purified(P-Mg)using a melt self-purification approach and reinforced using indigenously synthesized nanohydroxyapatite(HAP,0.6 wt.%)and strontium substituted nanohydroxyapatite(SrHAP,0.6 wt.%)using a low-cost stir assisted squeeze casting method to control their degradation rate.Using electron back-scattered diffraction(EBSD)and X-ray diffraction(XRD)examinations,all casted materials were carefully evaluated for microstructure and phase analysis.Mechanical characteristics,in vitro degradation,and in vitro biocompatibility with murine pre-osteoblasts were also tested on the fabricated alloys.For in vivo examination of bone formation,osteointegration,and degradation rate,the magnesium-based alloys were fabricated as small cylindrical pins with a diameter of 2.7 mm and a height of 2 mm.The pins were implanted in a critical-sized defect in a rat femur shaft(2.7 mm diameter and 2 mm depth)for 8 weeks and evaluated by microCT and histological evaluation for bone growth and osteointegration.When compared to P-Mg and P-MgHAP,micro-CT and histological analyses revealed that the P-MgSrHAP group had the highest bone formation towards the periphery of the implant and hence maximum osteointegration.When the removed pins from the bone defect were analyzed using GIXRD,they displayed hydroxyapatite peaks that were consistent with bio-integration.For P-Mg,P-MgHAP,and P-MgSrHAP 8 weeks after implantation,in vivo degradation rates derived from micro-CT were around 0.6 mm/year,0.5 mm/year,and 0.1 mm/year,respectively.Finally,P-MgSrHAP possesses the requisite degradation rate as well as sufficient mechanical and biological properties,indicating that it has the potential to be used in the development/fabrication of biodegradable bioactive orthopaedic implants.

Surface plasmon polariton and mode transformation in a nanoscale lossy metallic cylindrical cable

A theoretical investigation on the surface plasmon polariton in a gold cylindrical nanocable is presented. By solving a complete set of Maxwell＇s equations in the nanocable （with a 50 nm radius gold nanocore, 10-300 nm silica layer, and 30-200nm gold nanocladding）, the dispersion relations on the optical frequency and on the silica thickness are discussed. When the silica thickness varies from 50 to 250 nm, at a fixed waveleltgth, the strong coupling between the gold nanocore and the nanocladding leads to a symmetric-like surface mode and an antisymmetric-like surface mode in the nanocable. The transformation between the surface mode and the waveguide mode in this structure is also investigated. The results will be helpful for understanding the surface waves in the subwavelength structures.

Irradiation Damage of Nano-C2S Particles Studied by In-Situ Transmission Electron Microscopy

Development of a reactive nanocement is a new approach to improve the physical and chemical properties of construction materials. However, due to the decreased size of cement particles, beam damage during transmission electron microscope （TEM） observation becomes more severe than in conventional cement. In this work, irradiation damage to nano-C2S （dicalcium silicate） is observed and studied by in-situ evolution of diffraction patterns （DP）, high resolution TEM （HRTEM）, and electron energy-loss spectroscopy （EELS）. The results show that the damage to nano-C2S occurs through a decomposition reaction. Nano-C2S is first amorphized, and then re-crystallized into CaO nano-crystals with average size of 7 nm surrounded by an amorphous matrix of Si and SiO2. During this process, C2S particles exhibit volume shrinkage. The damage energy causing the reaction was analyzed and electron-electron inelastic scattering produced radiolysis and heat, leading to the observed phenomena.

WS_2 nanoplates embedded in graphitic carbon nanotubes with excellent electrochemical performance for lithium and sodium storage

WS2 has been considered as a promising anode material due to its high lithium storage capacity as well as fascinating physical properties. However, the insufficient electrical and ionic conductivities deteriorate the rate per- formance of the batteries. Herein, we report a simple synthetic approach towards graphene-WS2 hybrids by rolling graphene into a hollow nanotube in which WSz nanoplates are en- capsulated. This new electrode design strategy facilitates the fabrication of integrated and binder-free lithium ion battery and sodium ion battery electrodes by combining electrospin- ning and chemical vapor deposition （CVD） methods. Bene- fiting from their confined growth and the interconnected in- situ graphitic carbon coating nanocable web, the WS2@G with nano-level WS2 dispersion not only provides an efficiently conductive and electrolyte accessible framework, but effec- tively alleviates the volume change during the cycling, en- abling a mechanically robust binder-free electrode along with the outstanding electrochemical Li＋ and Na＋ storage proper- ties.