Three-Dimensional Graphene-Carbon Nanotube-Ni Hierarchical Architecture as a Polysulfide Trap for Lithium-Sulfur Batteries.

Despite their high energy density and affordable cost compared to lithium-ion (Li-ion) batteries, lithium-sulfur (Li-S) batteries still endure from slow reaction kinetics and capacity loss induced by the insulating sulfur and severe polysulfide diffusion. To address these issues, we report here nickel nanoparticles filled in vertically grown carbon nanotubes (CNTs) on graphene sheets (graphene-CNT-nickel composite (Gr-CNT-Ni)) that are coated onto a polypropylene separator as a polysulfide trap for the construction of high-loading sulfur cathodes. The hierarchical porous framework of Gr-CNT physically entraps and immobilizes the active material sulfur, while the strong chemical interaction with Ni nanoparticles in Gr-CNT-Ni inhibits polysulfide diffusion. The covalently interconnected electron conduction channels and carbon shell-confined metal active sites provide feasible paths for the continual regeneration of active material during the charge-discharge process. Benefitting from these novel morphological and structural features, the Li-S cell with the Gr-CNT-Ni as a polysulfide trap demonstrates high specific capacity and good cycle life. This work provides new avenues for synergistically combining the advantages of hierarchical porous carbon architectures and metal active sites for the development of high-performance cathodes for Li-S batteries.

Ni-Co bimetal nanowires filled multiwalled carbon nanotubes for the highly sensitive and selective non-enzymatic glucose sensor applications.

The facile, time and cost efficient and environmental benign approach has been developed for the preparation of Nickel (Ni)-Cobalt (Co) alloy nanowires filled multiwalled carbon nanotubes (MWCNTs) with the aid of mesoporous silica nanoparticles (MSN)/Ni-Co catalyst. The controlled incorporation of Ni-Co nanostructures in the three dimensional (3D) pore structures of MSN yielded the catalytically active system for the MWCNT growth. The inner surface of MWCNTs was quasi-continuously filled with face-centered cubic (fcc) structured Ni-Co nanowires. The as-prepared nanostructures were exploited as non-enzymatic electrochemical sensor probes for the reliable detection of glucose. The electrochemical measurements illustrated that the fabricated sensor exhibited an excellent electrochemical performance toward glucose oxidation with a high sensitivity of 0.695 mA mM-1 cm-2, low detection limit of 1.2 µM, a wide linear range from 5 µM-10 mM and good selectivity. The unprecedented electrochemical performances obtained for the prepared nanocomposite are purely attributed to the synergistic effects of Ni-Co nanowires and MWCNTs. The constructed facile, selective and sensitive glucose sensor has also endowed its reliability in analyzing the human serum samples, which wide opened the new findings for exploring the novel nanostructures based glucose sensor devices with affordable cost and good stability.

The Photovoltaic Performances of PVdF-HFP Electrospun Membranes Employed Quasi-Solid-State Dye Sensitized Solar Cells.

The PVdF-HFP nanofiber membranes with different molecular weight were prepared by electrospinning technique and were investigated as solid state electrolyte membranes in quasi solid state dye sensitized solar cells (QS-DSSC). The homogeneously distributed and fully interconnected nanofibers were obtained for all of the prepared PVdF-HFP electrospun membranes and the average fiber diameters of fabricated membranes were dependent upon the molecular weight of polymer. The thermal stability of electrospun PVdF-HFP membrane was decreased with a decrement of molecular weight, specifying the high heat transfer area of small diameter nanofibers. The QS-DSSC fabricated with the lower molecular weight PVdF-HFP electrospun nanofiber membrane exhibited the power conversion efficiency of 1 = 5.38%, which is superior over the high molecular weight membranes and is comparable with the liquid electrolyte. Furthermore, the electrospun PVdF-HFP membrane exhibited long-term durability over the liquid electrolyte, owing to the higher adsorption and retention efficiencies of liquid electrolyte in its highly porous and interconnected nanofibers. Thus the proposed electrospun PVdF-HFP membrane effectively tackled the volatilization and leakage of liquid electrolyte and provided good photoconversion efficiency associated with an excellent stability, which constructs the prepared electrospun membranes as credible solid state candidates for the application of QS-DSSCs.