Highly Crystalline Contorted Coronene Homologous Molecule as Superior Organic Anode Material for Full-Cell Li-Ion Batteries.

Organic anode materials have garnered attention for use in rechargeable Li-ion batteries (LIBs) owing to their lightweight, cost-effectiveness, and tunable properties. However, challenges such as high electrolyte solubility and limited conductivity, restrict their use in full-cell LIBs. Here, we report the use of highly crystalline Cl-substituted contorted hexabenzocoronene (Cl-cHBC) as an efficient organic anode for full-cell LIBs.

Pressure enabled organic reactions via confinement between layers of 2D materials.

Confinement of reactants within nanoscale spaces of low-dimensional materials has been shown to provide reorientation of strained reactants or stabilization of unstable reactants for synthesis of molecules and tuning of chemical reactivity. While few studies have reported chemistry within zero-dimensional pores and one-dimensional nanotubes, organic reactions in confined spaces between two-dimensional materials have yet to be explored. Here, we demonstrate that reactants confined between atomically thin sheets of graphene or hexagonal boron nitride experience pressures as high as 7 gigapascal, which allows the propagation of solvent-free organic reactions that ordinarily do not occur under standard conditions.

Physical Adsorption of Polyacrylic Acid on Boron Nitride Nanotube Surface and Enhanced Thermal Conductivity of Poly(vinyl alcohol) Composites.

To fully tap into the potential of boron nitride nanotubes (BNNTs), addressing their inherent insolubility was imperative. In this study, a water-soluble polymer, poly(acrylic acid) (PAA), was employed as a surface-active reagent, using an accessible and scalable approach. The physical properties and structure of PAA-BNNT were meticulously confirmed through valuable characterization techniques, encompassing X-ray diffraction, scanning electron microscopy, Fourier-transform infrared, X-ray photoelectron spectroscopy, and thermogravimetric analysis.

Facile covalent functionalization of boron nitride nanotubes coupling reaction.

A broad range of functionalized boron nitride nanotubes has been synthesized using a facile method based on the coupling reaction between BNNT and arenediazonium tetrafluoroborate derivatives. The formation of covalent bonds between nanotubes and organic moieties results in homogeneous dispersions in organic solvents, such as ,'-dimethylformamide, acetone, isopropanol, and tetrahydrofuran. Digital images demonstrated improved and stabilized dispersions lasting for several days, while TEM analysis indicated no breakdown of nanotubes due to the mild reaction conditions employed.

Gradient Lithium Metal Infusion in Ag-Decorated Carbon Fibers for High-Capacity Lithium Metal Battery Anodes.

Lithium (Li) metal is a promising anode material for high-energy-density Li batteries due to its high specific capacity. However, the uneven deposition of Li metal causes significant volume expansion and safety concerns. Here, we investigate the impact of a gradient-infused Li-metal anode using silver (Ag)-decorated carbonized cellulose fibers (Ag@CC) as a three-dimensional (3D) current collector.

Lyotropic Boron Nitride Nanotube Liquid Crystals: Preparation, Characterization, and Wet-Spinning for Fabrication of Composite Fiber.

Microfiber fabrication via wet-spinning of lyotropic liquid crystals (LCs) with anisotropic nanomaterials has gained increased attention due to the microfibers' excellent physical/chemical properties originating from the unidirectional alignment of anisotropic nanomaterials along the fiber axis with high packing density. For wet-spinning of the microfibers, however, preparing lyotropic LCs by achieving high colloidal stability of anisotropic nanomaterials, even at high concentrations, has been a critically unmet prerequisite, especially for recently emerging nanomaterials. Here, we propose a cationically charged polymeric stabilizer that can efficiently be adsorbed on the surface of boron nitride nanotubes (BNNTs), which provide steric hindrance in combination with Coulombic repulsion leading to high colloidal stability of BNNTs up to 22 wt %.

Selective Blocking of Graphene Defects Using Polyvinyl Alcohol through Hydrophilicity Difference.

Defects on graphene over a micrometer in size were selectively blocked using polyvinyl alcohol through the formation of hydrogen bonding with defects. Because this hydrophilic PVA does not prefer to be located on the hydrophobic graphene surface, PVA selectively filled hydrophilic defects on graphene after the process of deposition through the solution. The mechanism of the selective deposition via hydrophilic-hydrophilic interactions was also supported by scanning tunneling microscopy and atomic force microscopy analysis of selective deposition of hydrophobic alkanes on hydrophobic graphene surface and observation of PVA initial growth at defect edges.

Two-Dimensional Stacked Composites of Self-Assembled Alkane Layers and Graphene for Transparent Gas Barrier Films with Low Permeability.

Self-assembled alkane layers are introduced between graphene layers to physically block nanometer size defects in graphene and lateral gas pathways between graphene layers. A well-defined hexatriacontane (HTC) monolayer on graphene could cover nanometer-size defects because of the flexible nature and strong intermolecular van der Waals interactions of alkane, despite the roughness of graphene. In addition, HTC multilayers between graphene layers greatly improve their adhesion.

Highly Aligned Array of Heterostructured Polyflourene-Isolated Boron Nitride and Carbon Nanotubes.

Boron nitride nanotubes (BNNTs) have attracted increasing attention for their exceptional thermal, electronic, and optical properties. However, the progress in BNNTs applications has largely been limited by the low purity of as-synthesized BNNTs and inefficient solution-processing protocols due mainly to the instability of BNNTs in most of the solvents. Therefore, fabrication of highly pure, stable, and fully individualized BNNTs in a rational manner is required.

Dual growth mode of boron nitride nanotubes in high temperature pressure laser ablation.

The morphological analysis of the end of boron nitride nanotubes (BNNTs) using high-resolution transmission electron microscopy (HR-TEM) can provide valuable insight into the growth mechanism in high temperature pressure (HTP) laser ablation where the best quality of BNNT materials can be obtained so far. Two growth modes of BNNT coexisting during the synthesis process have been proposed based on HR-TEM observation and length analysis. One is the root growth mode, in which boron nitride (BN) species formed via the surface interaction between surrounding N molecules and boron nanodroplets incorporate into the tubular structure.

Capacitive Organic Anode Based on Fluorinated-Contorted Hexabenzocoronene: Applicable to Lithium-Ion and Sodium-Ion Storage Cells.

Conducting polymer-based organic electrochemical capacitor materials have attracted attention because of their highly conductive nature and highly reversible redox reactions on the surface of electrodes. However, owing to their poor stabilities in aprotic electrolytes, alternative organic electrochemical capacitive electrodes are being actively sought. Here, fluorine atoms are introduced into contorted hexabenzocoronene (cHBC) to achieve the first small-molecule-based organic capacitive energy-storage cells that operate at high current rates with satisfactory specific capacities of ≈160 mA h g and superior cycle capabilities (>400) without changing significantly.

Epitaxially Self-Assembled Alkane Layers for Graphene Electronics.

The epitaxially grown alkane layers on graphene are prepared by a simple drop-casting method and greatly reduce the environmentally driven doping and charge impurities in graphene. Multiscale simulation studies show that this enhancement of charge homogeneity in graphene originates from the lifting of graphene from the SiO surface toward the well-ordered and rigid alkane self-assembled layers.

Solvent-dependent conductance decay constants in single cluster junctions.

Single-molecule conductance measurements have focused primarily on organic molecular systems. Here, we carry out scanning tunneling microscope-based break-junction measurements on a series of metal chalcogenide CoSe clusters capped with conducting ligands of varying lengths. We compare these measurements with those of individual free ligands and find that the conductance of these clusters and the free ligands have different decay constants with increasing ligand length.

Extraordinary Strong Fluorescence Evolution in Phosphor on Graphene.

Optical transition between singlet and triplet is observed in phosphorescent platinum octaethylporphyrin (PtOEP), on a graphene substrate. PtOEP on single layer of graphene not only modulates the dominant emission wavelength but also enhances the emission intensity. This result addresses new light-matter interactions of the hybrid structure of graphene and a single molecule.

Exploring cultural differences in women's body weight perception: The impact of self-construal on perceived overweight and engagement in health activities.

We examined the cultural influence on perceived body weight and the level of health practices at a national and individual level. At a national level, we found that Japanese women (n = 80) overestimate body weight more than Korean (n = 82) and American (n = 63) women. At an individual level, individuals with interdependent self-construal were more prone to overestimate weight than those with independent self-construal (N = 182; American women).

Two-dimensional crystals from reduced symmetry analogues of trimesic acid.

The two-dimensional assembly of multicarboxylated arenes is explored at the liquid-graphite interface using scanning tunneling microscopy. Symmetry variations were introduced via phenylene spacer addition and the influence of these perturbations on the formation of hydrogen-bonded motifs from an alkanoic acid solvent is observed. This work demonstrates the importance of symmetry in 2D crystal formation and draws possible links of this behavior to prediction of coordination modes in three-dimensional coordination polymers.

Using self-organization to control morphology in molecular photovoltaics.

This work explores the formation of well-defined molecular p-n junctions in solution-processed self-assembled heterojunction solar cells using dodecyloxy-substituted contorted hexabenzocoronene (12-c-HBC) as a donor material and phenyl-C(70)-butyric acid methyl ester (PC(70)BM) as an acceptor. We find that the contorted 12-c-HBC molecules effectively assemble in solution to form a nested structure with the ball-shaped PC(70)BM. The result is a self-assembled molecular-scale p-n junction.

Importance of direct metal-π coupling in electronic transport through conjugated single-molecule junctions.

We study the effects of molecular structure on the electronic transport and mechanical stability of single-molecule junctions formed with Au point contacts. Two types of linear conjugated molecular wires are compared: those functionalized with methylsulfide or amine aurophilic groups at (1) both or (2) only one of its phenyl termini. Using scanning tunneling and atomic force microscope break-junction techniques, the conductance of mono- and difunctionalized molecular wires and its dependence on junction elongation and rupture forces were studied.