Fast crystallographic texture mapping of atomically thin hBN films on Ni(111) using secondary electron contrast.

High-throughput characterisation and fast sample quality feedback loops are essential for accelerating the development of advanced materials and their technological applications. This is particularly pertinent to the chemical vapor deposition (CVD) driven industrialisation of ultra-thin device materials, like hBN, where a complex texture at the atomic layer level remains hard to characterise efficiently, particularly over large areas. Here, we show that secondary electron contrast can be used to fingerprint the alignment of monolayer hBN domains with the Ni(111) surface, thus opening fast crystallographic texture mapping capabilities with conventional scanning electron microscopy (SEM).

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.

Developments and further applications of ephemeral data derived potentials.

Machine-learned interatomic potentials are fast becoming an indispensable tool in computational materials science. One approach is the ephemeral data-derived potential (EDDP), which was designed to accelerate atomistic structure prediction. The EDDP is simple and cost-efficient.

Direct Electrochemical Functionalization of Graphene Grown on Cu Including the Reaction Rate Dependence on the Cu Facet Type.

We present an electrochemical method to functionalize single-crystal graphene grown on copper foils with a (111) surface orientation by chemical vapor deposition (CVD). Graphene on Cu(111) is functionalized with 4-iodoaniline by applying a constant negative potential, and the degree of functionalization depends on the applied potential and reaction time. Our approach stands out from previous methods due to its transfer-free method, which enables more precise and efficient functionalization of single-crystal graphene.

Benzotrithiophene-based Covalent Organic Framework Photocatalysts with Controlled Conjugation of Building Blocks for Charge Stabilization.

Covalent organic frameworks have recently shown high potential for photocatalytic hydrogen production. However, their structure-property-activity relationship has not been sufficiently explored to identify a research direction for structural design. Herein, we report the design and synthesis of four benzotrithiophene (BTT)-based covalent organic frameworks (COFs) with different conjugations of building units, and their photocatalytic activity for hydrogen production.

Geomimetic Hydrothermal Synthesis of Polyimide-Based Covalent Organic Frameworks.

Despite its abundance, water is not widely used as a medium for organic reactions. However, under geothermal conditions, water exhibits unique physicochemical properties, such as viscosity and a dielectric constant, and the ionic product become similar to those of common organic solvents. We have synthesized highly crystalline polyimide-based covalent organic frameworks (PICs) under geomimetic hydrothermal conditions.

Catalyst- and Solvent-Free Synthesis of a Chemically Stable Aza-Bridged Bis(phenanthroline) Macrocycle-Linked Covalent Organic Framework.

Developing new linkage-based covalent organic frameworks (COFs) is one of the major topics in reticular chemistry. Electrically conductive COFs have enabled applications in energy storage and electrochemical catalysis, which are not feasible using insulating COFs. Despite significant advances, the construction of chemically stable conductive COFs by the formation of new linkages remains relatively unexplored and challenging.

Synthesis of a Copper 1,3,5-Triamino-2,4,6-benzenetriol Metal-Organic Framework.

We report the synthesis and characterization of a two-dimensional (2D) MXY-type (M = metal, X, Y = N, S, O, and X ≠ Y) copper 1,3,5-triamino-2,4,6-benzenetriol metal-organic framework (Cu(TABTO)-MOF). The role of oxygen in the synthesis of this MOF was investigated. Copper metal is formed along with the MOF when the synthesis is done in argon as suggested by XRD.

Tailored Poly(vinylidene fluoride--trifluoroethylene) Crystal Orientation for a Triboelectric Nanogenerator through Epitaxial Growth on a Chitin Nanofiber Film.

Tailoring the crystal orientation of poly(vinylidene fluoride--trifluoroethylene) (PVDF-TrFE) has attracted widespread interest because of its effects on the ferroelectric properties required for various electronic devices. In this study, we investigated the epitaxial growth of PVDF-TrFE on a chitin film for developing triboelectric nanogenerators (TENGs). The crystallographic match between the chitin and PVDF-TrFE enables the development of the intended crystal orientation, with the PVDF-TrFE polarization axis aligned perpendicular to the substrate.

Excess-Li Localization Triggers Chemical Irreversibility in Li- and Mn-Rich Layered Oxides.

Li- and Mn-rich layered oxides (LMRs) have emerged as practically feasible cathode materials for high-energy-density Li-ion batteries due to their extra anionic redox behavior and market competitiveness. However, sluggish kinetics regions (<3.5 V vs Li/Li ) associated with anionic redox chemistry engender LMRs with chemical irreversibility (first-cycle irreversibility, poor rate properties, voltage fading), which limits their practical use.

Multi-Color Luminescence Transition of Upconversion Nanocrystals via Crystal Phase Control with SiO for High Temperature Thermal Labels.

Upconversion nanocrystals (UCNs)-embedded microarchitectures with luminescence color transition capability and enhanced luminescence intensity under extreme conditions are suitable for developing a robust labeling system in a high-temperature thermal industrial process. However, most UCNs based labeling systems are limited by the loss of luminescence owing to the destruction of the crystalline phase or by a predetermined luminescence color without color transition capability. Herein, an unusual crystal phase transition of UCNs to a hexagonal apatite phase in the presence of SiO nanoparticles is reported with the enhancements of 130-fold green luminescence and 52-fold luminance as compared to that of the SiO-free counterpart.

Hydrogen-Bond Free Energy of Local Biological Water.

Here, we propose an experimental methodology based on femtosecond-resolved fluorescence spectroscopy to measure the hydrogen (H)-bond free energy of water at protein surfaces under isothermal conditions. A demonstration was conducted by installing a non-canonical isostere of tryptophan (7-azatryptophan) at the surface of a coiled-coil protein to exploit the photoinduced proton transfer of its chromophoric moiety, 7-azaindole. The H-bond free energy of this biological water was evaluated by comparing the rates of proton transfer, sensitive to the hydration environment, at the protein surface and in bulk water, and it was found to be higher than that of bulk water by 0.

Chemically induced transformation of chemical vapour deposition grown bilayer graphene into fluorinated single-layer diamond.

Notwithstanding the numerous density functional studies on the chemically induced transformation of multilayer graphene into a diamond-like film carried out to date, a comprehensive convincing experimental proof of such a conversion is still lacking. We show that the fluorination of graphene sheets in Bernal (AB)-stacked bilayer graphene grown by chemical vapour deposition on a single-crystal CuNi(111) surface triggers the formation of interlayer carbon-carbon bonds, resulting in a fluorinated diamond monolayer ('F-diamane'). Induced by fluorine chemisorption, the phase transition from (AB)-stacked bilayer graphene to single-layer diamond was studied and verified by X-ray photoelectron, UV photoelectron, Raman, UV-Vis and electron energy loss spectroscopies, transmission electron microscopy and density functional theory calculations.

Partial Oxidation-Induced Electrical Conductivity and Paramagnetism in a Ni(II) Tetraaza[14]annulene-Linked Metal Organic Framework.

We report the synthesis and characterization of a two-dimensional (2D) conjugated Ni(II) tetraaza[14]annulene-linked metal organic framework () where is a macrocyclic MN (M = metal, N = nitrogen) compound. The structure of was elucidated by Fourier-transform infrared, X-ray photoemission, and X-ray diffraction spectroscopies, in combination with density functional theory (DFT) calculations. When chemically oxidized by iodine, the insulating bulk (σ < 10 S/cm) exhibits an electrical conductivity of 0.

Understanding of Fluorination Dependence on Electron Mobility and Stability of Naphthalenediimide-Based Polymer Transistors in Environment with 100% Relative Humidity.

A family of copolymers (P(NDIOD-T2F)) based on naphthalenediimide (NDI) and 2,2'-bithiophene (T2) units with different amounts of 3,3'-difluoro-2,2'-bithiophene (T2F) decoration were synthesized, characterized, and used in n-type organic field-effect transistors (OFETs). With increasing T2F content in the backbone, we observe increased melting and crystallization transitions, blue-shifted absorptions, and deeper-lying highest occupied molecular orbital (HOMO)/lowest unoccupied molecular orbital (LUMO) levels, together with improved hydrophobicity. The highest electron mobility of 4.

Biomimetic Superoxide Disproportionation Catalyst for Anti-Aging Lithium-Oxygen Batteries.

Reactive oxygen species or superoxide (O), which damages or ages biological cells, is generated during metabolic pathways using oxygen as an electron acceptor in biological systems. Superoxide dismutase (SOD) protects cells from superoxide-triggered apoptosis by converting superoxide to oxygen and peroxide. Lithium-oxygen battery (LOB) cells have the same aging problems caused by superoxide-triggered side reactions.

Organic Radical-Linked Covalent Triazine Framework with Paramagnetic Behavior.

The production of multifunctional pure organic materials that combine different sizes of pores and a large number of electron spins is highly desirable due to their potential applications as polarizers for dynamic nuclear polarization-nuclear magnetic resonance and as catalysts and magnetic separation media. Here, we report a polychlorotriphenylmethyl radical-linked covalent triazine framework (PTMR-CTF). Two different sizes of micropores were established by N sorption and the presence of unpaired electrons (carbon radicals) by electron spin resonance and superconducting quantum interference device-vibrating sample magnetometer analyses.

N- and B-Codoped Graphene: A Strong Candidate To Replace Natural Peroxidase in Sensitive and Selective Bioassays.

The work describes a carbon-based peroxidase mimic, N- and B-codoped reduced graphene oxide (NB-rGO), which shows high peroxidase-like activity without oxidase-like activity and has a catalytic efficiency nearly 1000-fold higher than that of undoped rGO. The high catalytic activity of NB-rGO is explained by density functional theory by calculating Gibbs free energy change during the peroxide decomposition reaction. Acetylcholine and C-reactive protein are successfully quantified with high sensitivity and selectivity, which were comparable to or better than those obtained using natural peroxidase.

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.

Porous Two-Dimensional Monolayer Metal-Organic Framework Material and Its Use for the Size-Selective Separation of Nanoparticles.

Rational bottom-up construction of two-dimensional (2D) covalent or noncovalent organic materials with precise structural control at the atomic or molecular level remains a challenge. The design and synthesis of metal-organic frameworks (MOFs) based on new building blocks is of great significance in achieving new types of 2D monolayer MOF films. Here, we demonstrate that a complexation between copper(II) ions and tri(β-diketone) ligands yields a novel 2D MOF structure, either in the form of a powder or as a monolayer film.

Hierarchical Chitin Fibers with Aligned Nanofibrillar Architectures: A Nonwoven-Mat Separator for Lithium Metal Batteries.

Here, we introduce regenerated fibers of chitin (Chiber), the second most abundant biopolymer after cellulose, and propose its utility as a nonwoven fiber separator for lithium metal batteries (LMBs) that exhibits an excellent electrolyte-uptaking capability and Li-dendrite-mitigating performance. Chiber is produced by a centrifugal jet-spinning technique, which allows a simple and fast production of Chibers consisting of hierarchically aligned self-assembled chitin nanofibers. Following the scrutinization on the Chiber-Li-ion interaction via computational methods, we demonstrate the potential of Chiber as a nonwoven mat-type separator by monitoring it in Li-O and Na-O cells.

Li-Ion Battery Cathodes: Enhancing Interfacial Bonding between Anisotropically Oriented Grains Using a Glue-Nanofiller for Advanced Li-Ion Battery Cathode (Adv. Mater. 23/2016).

The formation of a spinel Lix CoO2 layer in a Ni-rich secondary particle for lithium-ion batteries is reported by S. K. Kwak, J.

Dynamics of Mitochondrial Transport in Axons.

The polarized structure and long neurites of neurons pose a unique challenge for proper mitochondrial distribution. It is widely accepted that mitochondria move from the cell body to axon ends and vice versa; however, we have found that mitochondria originating from the axon ends moving in the retrograde direction never reach to the cell body, and only a limited number of mitochondria moving in the anterograde direction from the cell body arrive at the axon ends of mouse hippocampal neurons. Furthermore, we have derived a mathematical formula using the Fokker-Planck equation to characterize features of mitochondrial transport, and the equation could determine altered mitochondrial transport in axons overexpressing parkin.