One-pot synthesis of tin chalcogenide-reduced graphene oxide-carbon nanotube nanocomposite as anode material for lithium-ion batteries.

In this study, a ternary tin chalcogenide (TC)-reduced graphene oxide (RGO)-carbon nanotube (CNT) nanocomposite was synthesized as a lithium-ion battery (LIB) anode by a simple one-step protocol. The nanocomposite was prepared through a hydrothermal method using tin chloride as the tin precursor, thiourea as the sulfur source and reducing agent, and GO-CNT hybrid as the carbonaceous nanostructure. The structure, morphology, and phase analysis of the synthesized nanocomposite powder were investigated using Raman spectroscopy, field-emission scanning electron microscopy (FESEM), and X-ray diffraction (XRD). The results show that GO is reduced while SnS and SnS2 nanosheets along with SnO2 nanoparticles are simultaneously formed within the RGO-CNT hybrid framework throughout the hydrothermal process. During the first lithiation-delithiation process, the discharge capacity and the columbic efficiency for the ternary TC-RGO-CNT nanocomposite electrode at a current density of 50 mA g-1 are 1401 mA h g-1 and 50%, respectively. The TC-RGO-CNT electrode gives an improved capacity of 197 mA h g-1 at 500 mA g-1 while the corresponding value for the bare TC, and binary TC-CNT and TC-RGO nanocomposite electrodes was only 5, 18, and 41 mA h g-1, respectively. Meanwhile, the ternary nanocomposite anode indicates outstanding stability after 150 cycles with a reversible capacity of 100 mA h g-1 at 500 mA g-1. The excellent electrochemical performance of the ternary TC-RGO-CNT nanocomposite is ascribed to the synergistic effect of the high capacity of electrochemically-active TC nanostructures along with the large surface area, porous structure, and exceptional conductivity of the 3D RGO-CNT framework.

Correction: Capacitive behaviour of nanocrystalline octacalcium phosphate (OCP) (Ca8H2(PO4)6·5H2O) as an electrode material for supercapacitors: biosupercaps.

Correction for 'Capacitive behaviour of nanocrystalline octacalcium phosphate (OCP) (Ca8H2(PO4)6·5H2O) as an electrode material for supercapacitors: biosupercaps' by Mustafa Tuncer et al., Nanoscale, 2019, 11, 18375-18381.

The adsorption effect of freestanding SiOx-decorated stabilized polyacrylonitrile interlayers in lithium-sulfur batteries.

Lithium-sulfur batteries are well-known for their high theoretical specific capacity and high energy density. However, they undergo rapid capacity fading after the initial cycles due to the dissolution of polysulfides which further results in the shuttle effect. To address this issue and to protect the Li anode surface, silicon suboxide decorated stabilized polyacrylonitrile (sPAN-SiOx) fibermats are used as a freestanding interlayer on the cathode side. Polysulfides are easily captured at the cathode side with the help of the complementary adsorption effect of oxygen-containing functional groups, SiOx and the pyridinic-N structure of sPAN-SiOx resulting in better electrochemical cell performance. The adsorption effect of those functional groups and SiOx is confirmed by X-Ray Photoelectron Spectroscopy (XPS) analysis as obvious shifts in the binding energies and reductions of the peak intensities in the presence of polysulfides. The battery cell with the sPAN-SiOx interlayer shows a discharge capacity of 646 mA h g-1 after 100 cycles of charge-discharge at C/5 current density which is a significant increase compared to the cells with a stabilized polyacrylonitrile (sPAN) interlayer or the cells without an interlayer.

DNA Directed Self-Assembly of Single Walled Carbon Nanotubes into Three-Way Junction Nanostructures.

Utilization of a self-assembled two-dimensional DNA nanostructure to arrange single-walled carbon nanotubes (SWNTs) into predetermined structures at controllable angles is presented. A specially designed DNA three-way junction (3WJ) composed of three double-stranded DNA arms containing single-stranded overhang sequences was prepared by annealing of partially complementary ssDNA sequences and ultrasonicated with SWNTs, resulting in DNA-3WJ/SWNT hybrid nanostructures. Utilization of DNA-3WJ not only allowed the precise dispersion of SWNTs but also acted as a rigid template for the self-assembly of SWNTs into three-armed junctions at an angle of approximately 120° to each other as visualized by scanning electron microscopy and atomic force microscopy. Prepared DNA-3WJ/SWNT nanostructures were also demonstrated to have the appropriate binding sites for fluorophores, providing a simple method for the fluorescent labeling of SWNTs. When ssDNA sequences forming the DNA-3WJ are ultrasonicated with SWNTs, followed by annealing of resulting ssDNA wrapped SWNTs, instead of hybrid junctions composed of three SWNT molecules, a web-like structure composed of interconnected SWNT junctions was obtained. The design approaches demonstrated here provide simple methods for the arrangement of SWNTs into desired nanostructures utilizing pre-assembled DNA nanostructures as linkers in aqueous solution through noncovalent interactions which can greatly contribute to efforts along the controlled assembly of SWNTs.

Synthesis of POSS-Functionalized Polyisobutylene via Direct Initiation.

POSS-functionalized polyisobutylenes (PIBs) were synthesized by carbocationic polymerization using an epoxy-POSS/TiCl(4) initiating system in hexane/methyl chloride (60:40 v/v) solvent mixture at -80 °C. (1) H NMR spectroscopy verified the incorporation of one epoxy-POSS per polymer chain. Light scattering and TEM analysis demonstrated the formation of 50-100 nm sized aggregates and micron-sized clusters.