Search

The graphene/carbon nanotube hybrid was designed and implemented by a deoxygenation process for direct electron transfer of glucose oxidase and glucose biosensor. The procedure was analyzed by transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman spectra, etc. The strategy of structurally engineering one-dimensional carbon nanotube (CNT) and two-dimensional graphene oxide (GO) presented three benefits: (a) a deoxygenation process between GO and acid-CNT was introduced under strongly alkaline condition; (b) GO prevented the irreversible integration of CNT; and (c) CNT hindered the restacking of GO. The RGO interacted with CNT through the van der Waals forces and π-π stacking interaction. The three-dimensional hybrid not only had a high surface area, but also exhibited a good electronic conductivity. A direct electrochemistry of glucose oxidase was obtained on the nanohybrid modified electrode which showed good response for glucose sensing. This study would provide a facile and green method for the preparation of nanohybrid for a wide range of applications including biosensing, super capacitor, and transparent electrode. [ABSTRACT FROM AUTHOR]

Nanostructured carbon materials have attracted enormous attention in last two decades due to their unique chemical, electrical, and mechanical properties. In this work, amorphous hollow carbon spheres (AHCSs) with diameters in the range of 100-750 nm, which are dispersed among bent graphitized carbon nanotubes, are synthesized by using radio frequency plasma enhanced chemical vapor deposition in mixed CH/H gases. The carbon spheres were characterized with scanning electron microscope, energy-dispersive X-ray spectroscopy, Raman spectroscopy, and transmission electron microscopy. It is found that MgO and Co/Ni nanoparticles as well as hydrogen play crucial roles in the formation of AHCSs. Moreover, a possible growth mechanism of AHCSs was proposed. The results of this study provide new insights into the fundamental understanding of nonstructural carbon materials toward applications in nanodevices. [ABSTRACT FROM AUTHOR]

A novel nitrogen-doped carbon nanosphere with lithiophilic ZnO nanoparticles encapsulated by interconnected pomegranate-like carbon sheets is designed and fabricated, and the lithium deposition behavior in it is systematically investigated via in-situ transmission electron microscopy. The well-designed pomegranate-like carbon sheets within the carbon nanosphere can prevent lithiophilic seeds from detaching or aggregating during cycling, and meanwhile offer individual void to accommodate deposited Li. Such a dual-confinement effect enables dendrite-free Li deposition and long cycling life. [Display omitted] • A novel pomegranate-like carbon nanosphere with lithiophilicity is constructed. • The well-designed carbon networks provide dual-confinement for Li encapsulation. • The ZnO@NPCS electrode delivers long cycling life with high average CEs. • In-situ TEM and phase-field simulations confirm the dual-confinement mechanism. • The dual-confinement strategy can be extended to other alkalis anodes. The uncontrollable dendrite growth and infinite volume expansion of Li during cycling lead to low Coulombic efficiency (CE) and short cycling life, severely impeding the commercial progress of lithium metal batteries (LMBs). In this work, nitrogen-doped carbon nanospheres (CSs) with ultrafine lithiophilic ZnO nanoparticles encapsulated by interconnected pomegranate-like carbon sheets (denoted as ZnO@NPCS) have been designed and constructed to serve as novel lithium hosts. The ultrafine ZnO nanoparticles uniformly distributed in the CSs can significantly reduce the Li nucleation barrier, while the well-designed pomegranate-like carbon sheets within the CSs can provide continuous and fast electron/ion transport channels, accelerating the Li+ transfer kinetics. Moreover, the internal interconnected carbon networks can confine the lithiophilic nanoparticles, preventing them from detaching or aggregating during cycling, and meanwhile offer individual voids to accommodate deposited Li. Thus, both lithiophilic seeds and deposited Li can be well confined in the pomegranate-like structure. Such a dual-confinement effect enables the ZnO@NPCS electrode to exhibit ultralong cycling life for more than 1000 cycles with ultrahigh CE (>99.5 %) without Li dendrites growth, which is further validated by in-situ transmission electron microscopy and phase-field simulations. Therefore, this dual-confinement strategy provides an inspiring insight to design superior Li hosts for developing superior LMBs and can be extended to other battery systems. [ABSTRACT FROM AUTHOR]

Ta–Si-C films were deposited by DC magnetron co-sputtering using TaC and Si targets in an Ar-discharge atmosphere. Increasing the current of Si target from 0.0 to 0.5 A led to a continuous increase of Si content from 0.0 to 30.8 at%. The effects of Si content on microstructure were systematically investigated using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). At low Si content (≤ 5.6 at%), Si occupied C vacancies to form a solid solution Ta(C, Si). Further increasing the Si content, some Si atoms bonded with C atoms resulting in the formation of amorphous phase (a-C:Si), and the films presented a nanocomposite structure consisting of solid solution Ta(C, Si) surrounded by a-C:Si matrix. At the highest Si content (30.8 at%), the film exhibited finally X-ray amorphous structures. The hardness ( H ) and fracture toughness ( K f ) were observed to initially increase and then decrease as the Si content was increased. At 5.6 at% Si, the film exhibited a maximum in H (44.9 ± 2.7 GPa) and K f (3.61 ± 0.16 MPa m 1/2 ), which can be ascribed to the formation of a solid solution. On further increasing the Si content, an amorphous phase gradually appeared, leading to a decrease in H and K f . [ABSTRACT FROM AUTHOR]

Abstract: In this study, we have developed a simple and green method for one-pot synthesis of ultrathin gold nanocrystals attached to graphene through photo irradiation. High-yield ultrathin Au nanocrystals are distributed on the reduced graphene oxide, immediately followed by the deoxygenation of graphene oxide in the absence of chemical reductants and surfactants. The procedure has been thoroughly completed and the products have been analyzed by transmission electron microscopy (TEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), etc. The results show that both graphene oxide and photo irradiation play essential roles in the formation of ultrathin Au nanocrystals. The nanohybrids also display excellent electro-catalytical performance to methanol oxidation. This study not only has potential in the applications of bio-sensing and fuel cells, but also provides new procedures for the preparation of metal/graphene nanomaterials. [Copyright &y& Elsevier]

Abstract: A novel hedgehog-like core/shell structure, consisting of a high density of vertically aligned graphene sheets and a thin graphene shell/a copper core (VGs-GS/CC), has been synthesized via a simple one-step synthesis route using radio-frequency plasma-enhanced chemical vapor deposition (RF-PECVD). Scanning and transmission electron microscopy investigations show that the morphology of this core/shell material could be controlled by deposition time. For a short deposition time, only multilayer graphene shell tightly surrounds the copper particle, while as the deposition time is relative long, graphene sheets extend from the surface of GS/CC. The GS can protect CC particles from oxidation. The growth mechanism for the obtained GS/CC and VGs-GS/CC has been revealed. Compared to VGs, VGs-GS/CC material exhibits a better electron field emission property. This investigation opens a possibility for designing a core/shell structure of different carbon–metal hybrid materials for a wide variety of practical applications. [Copyright &y& Elsevier]