2D Sheets Research Articles

Solid Oxide Cell Performance: Spatially Resolved Oxygen Electrode Stability

Solid Oxide Cell (SOC) electrolysis will play an important role in the electrification of the chemical, fertilizer, and fuel industries, contributing to the reduction of their reliance on fossil fuel feedstocks. The integration of high temperature steam and CO2-electrolyzers in industrial processes with readily available waste heat and renewable electricity allows for highly efficient green hydrogen production and methods for CO2 utilization.The development of next generation SOC electrolyzer technology at TNO aims to provide high performance and low-cost technological options for the electrification of the aforementioned chemicals and fuels industries. The ambition of the SOC technology development program is to assist the whole value chain, from cell manufacturing to end-users, by increasing the economic viability of the technology. In line with this ambition, the TNO R&D activities regarding SOC technology concentrate on cell and stack technology development coupled with techno-economic and business case studies on SOC technology integration in the industrial environment. Improvements in SOC performance and durability for electrolysis applications are of great importance for the successful industrial implementation of the technology. Hydrogen Europe targets for 2030 aim at low stack degradation rates of 0.5%/khr at thermoneutral voltage, while delivering current densities of at least 1.5 A/cm2. Therefore, lifetime improvements at high current density are one of the vocal points of SOC development efforts, which calls for a good understanding of the degradation phenomena and analytical methods to investigate the material stability in the SOC during electrolysis operation.In this contribution, the current status of SOC development and testing within TNO will be presented. Several aspects of TNO SOC performance characteristics will be discussed, with a focus on water electrolysis performance and lifetime behaviour during endurance tests of several thousand hours. Excellent water electrolysis performance of the TNO SOC cells is observed at thermoneutral voltage (1.3 V), achieving current density values of 1.75 A/cm2 at an operating temperature of 750 ºC. Lifetime assessment and material degradation of the SOC will be discussed, with a focus on the analysis of observed degradation phenomena in the oxygen electrode material. As oxygen electrode degradation can be critical for SOC performance in a stack environment, it is important to have a good understanding of the degradation processes and the ability to monitor them. At TNO, a novel high-resolution 2D mapping of the lateral conductivity of the oxygen electrode have been used as an effective tool for quality control and validation of the air electrode development. Additionally, the combination of 2D sheet resistance mapping, SEM-EDX and XRD techniques (Figure 1) provides a powerful combination of tools to obtain a spatially resolved (3D) view of the localized degradation observed in the oxygen electrode after several thousand hours of water electrolysis. Figure 1

Hierarchical 2D sheets of N and S co-doped Fe-based electrocatalyst for efficient oxygen reduction in advanced Zn-air battery

Currently, the scientific community is keenly interested in the design and production of efficient and durable transition metal electrocatalysts for oxygen reduction reactions (ORR). Therefore, this study reports a simple and reproducible N and S co-doped two-dimensional (2D) hierarchical porous electrocatalyst is reported. NSC the support material first was obtained by pyrolyzing trithiocyanuric acid (TTCA) and loaded on hemin to obtain the final material named Fe/NSC-800. 2D hierarchical porous structures with the large specific surface area were constructed by using TTCA as the template, S source, and additional N source. The addition of hemin not only retained the morphology of the NSC but also provided source of Fe for Fe/NSC-800. The Fe/NSC-800 possessed the limiting current density of 5.85 mA cm–2 and good ORR stability in 0.1 M KOH solution. Based on the excellent ORR performance of Fe/NSC-800, it was assembled into the primary Zn-air battery, which also exhibited satisfactory open circuit voltage (1.55 V) and energy density (880 W h kg–1). This work has contributed to the rational engineering and fabrication of high-performance ORR electrocatalysts for Zn-air battery applications.

The Effect of Spherical Hybrid Silica–Molybdenum Disulfide on the Lubricating Characteristics of Castor Oil

Abstract This investigation demonstrates the effect of a structural hybrid of spherical silica and lamellar molybdenum disulfide (MoS2) combined to form a sphere used as an antifriction and antiwear additive in vegetable oil in steel-on-steel tribopair. Hybrids demonstrated improved dispersion stability due to the deposition of lightweight silica on the surface of hydrothermally prepared 2D sheets of MoS2. The concentration of nanohybrid was optimized for optimal lubricant performance, and the best region of test space is presented in this work. At the optimum concentration, the coefficient of friction (COF) was 0.03236, with an average wear volume of 2.16 × 10−12 m3. The synergism of the particles significantly reduces friction and wear. The collision of the hybrid spheres with the surface has an immediate effect on it. The broken sphere of wear debris was observed under scanning electron microscopy. The wear debris analysis indicates that the lubrication mechanism begins with the rolling of hybrid spheres and ends with the rolling and sliding of silica and MoS2.

Synthesis, crystal structures, photophysical and antibacterial properties of Ag(I) and Zn(II) coordination polymers based on a flexible bisacylhydrazone ligand

A flexible bisacylhydrazone ligand (H4L) was designed and synthesized from the condensation reaction of dialdehyde 3,3′-thiobis(methyiene)-bis-(5-methyl-salicylaldehyde) (b) with isonicotinic hydrazide. In the DMSO/methanol solution, two coordination polymers (CPs), formulated as {[Ag(H4L)NO3]·DMSO·2H2O}n (CP 1) and {[Zn2(H2L2-)2]·3DMSO·3H2O}n (CP 2), were synthesized from H4L with Ag(I) or Zn(II) ions, respectively. These two CPs were characterized via elemental analysis, FT-IR spectra, and single crystal X-ray determination. The results show that CP 1 exists as a 1D looped-chain polymer, while CP 2 exists as a 2D sheet polymer. The coordination configurations of the two CPs were analyzed and compared in detail, which disclose the terminal pyridyl nitrogen atoms exhibit obviously stronger coordination ability compared to other sites. In addition, photophysical, electrochemical and antibacterial properties of H4L and the two CPs were investigated.

Synthesis, Characterization, Cytotoxicity, and Antibacterial Studies of Persea americana Mill. (Avocado) Seed Husk Mediated Hydronium Jarosite Nanoparticles

The application of nanotechnology in antimicrobial and cytotoxicity studies has recently been receiving increased interest. This paper report on the use of Persea americana Mill. (avocado) seed husk to synthesize hydronium jarosite nanoparticles in a facile, economical, and eco-friendly manner. We describe firstly the synthesis of hydronium jarosite nanoparticles using P. americana (avocado) seed husk aqueous extract as a reducing and chelating agent for the reduction of iron (II) sulfate heptahydrate. Secondly, we describe the characterization of the nanoproduct with scanning electron microscopy (SEM); energy dispersive X-ray spectroscopy (EDX); high-resolution transmission electron microscopy (HRTEM); X-ray powder diffraction (XRD) analysis; Fourier transform infrared spectroscopy (FT-IR); and, lastly, the cytotoxicity and antibacterial effect of hydronium jarosite nanoparticles using murine macrophage cells (Raw 264.7) cell lines, Gram-negative (Escherichia coli), Gram-positive (Staphylococcus aureus), and methicillin-resistant Staphylococcus aureus. These hydronium jarosite avocado seed husk-mediated nanoparticle-coated 2D sheets did not show any antibacterial activity against the bacteria tested but did show concentration-dependent cytotoxicity. Further research is required to optimize the antibacterial properties and reduce the cytotoxicity of this nanomaterial synthesized using green nanochemistry.

Efficient CO2 separation by ionic liquid nanoconfined in ultra-thin TCOH@Pebax-1657 MMM

Global climate change has continued to intensify in recent years, and the low efficiency of carbon emission reduction has become an important issue for many countries. Membrane separation technology has gained popularity in CO2 capture due to its ease of operation, environmental friendliness, and smaller area, etc. Two-dimensional (2D) sheet materials are one of the most promising materials for membrane separation technology. MXene has been used for gas separation because of its advantages such as high aspect ratio, excellent flexibility, and rich functional group surface. However, the stacking of massive MXene nanosheets lead to gas transport channel obstruction, causing the gas permeance to decrease. Herein, the hydroxylation of MXene was treated to obtain alkaline MXene nanosheets (TCOH) in this work. The stabilised TCOH and Pebax-1657 were used to make a mixed matrix membrane (MMM), while 1-ethyl-3-methylimidazolyl acetate ([EMIm][AcO], IL) was nanoconfined in the 2D channel of ultra-thin TCOH@Pebax-1657 MMM to construct a novel composite membrane for efficient CO2 capture. The TCOH@Pebax-1657/IL membrane prepared in this experiment has high CO2 permeance and the selectivity of CO2/N2, CO2/CH4 at the IL concentration of 35 wt%. In addition, the film has shown excellent thermal stability and durability over long periods of testing. Since TCOH is rarely used in the field of gas separation, the study will provide fresh idea for the preparation of highly efficient CO2 capture membranes.

A first-principles study on chemical adsorption of lithium polysulfide molecules: investigating the influence of carbon, boron, and nitrogen vacancies in boron carbon nitride 2D sheets

A first-principles study on chemical adsorption of lithium polysulfide molecules: investigating the influence of carbon, boron, and nitrogen vacancies in boron carbon nitride 2D sheets

Electronic band structures and optical properties of 2D XOF (X = Ga or In) oxyfluoride monolayers using density functional theory and GW approximation

The class of two-dimensional oxyfluoride monolayers is currently considered one of the most attractive nanomaterials for enhancing design and pushing the limits of different cutting-edge technologies. Two-dimensional semiconductor materials are the most promising systems for various applications in optoelectronic devices because they have a unique optical properties. We continue in this way by investigating the GW band structures and optical properties of unique 2D XOF (X = Ga or In) oxyfluoride monolayers, involving absorption, conductivity, refractive index, and dielectric function. We find no imaginary frequencies in the computed phonon spectra, indicating that these systems are dynamically stable. Furthermore, GaOF and InOF stay stable for temperatures T ≤ 840 K. The band gap of GaOF obtained with the single shot (G0W0) is larger than the band gap energy Eg of InOF. Where the direct band gap energies of GaOF and InOF are 6.1 eV and 4.8 eV, respectively. Our GW(PBE) numerical simulations demonstrate that the GaOF monolayer moves transparent once the frequency of the incoming light exceeds the plasma frequency (35.00 eV). Furthermore, InOF switches transparently once the incident light frequency exceeds the plasma frequency ∼ 35.00 eV. Interestingly, we obtain that these 2D sheets have a strong absorption coefficient in the range of ∼ 3.00–60.00 eV. They are emerging as a potential for the building blocks of the nano-size and ultra-thin optoelectronics of the future since they productively emit and absorb light.

High-performance solid-state asymmetric Supercapacitor based on α-Fe2O3/r-GO/GCN composite electrode material for energy storage application

Herein, a 3D/2D/2D of α-Fe2O3/r-GO/GCN composites were synthesized by combined reflux condensation and sonochemical-assisted wet-impregnation techniques. The physicochemical properties of the prepared materials were inspected by various analytical techniques. Morphology analysis techniques of different electron microscopes were employed to confirm the rhombohedral (3D) and two-dimensional (2D) sheets' morphology. The electrochemical behaviour of the as-synthesised electrode materials was assessed for use in a redox electrolyte-based energy storage system. Electrochemical measurements in a 6M KOH solution revealed that the electrode exhibited good supercapacitive behaviour. The 3D/2D/2D -α-Fe2O3/r-GO/GCN composite had a higher capacitance rate of roughly 810 F g−1 than α-Fe2O3 nanoparticles at 1Ag−1. From cyclic stability, ternary composite has good cyclic retention (98.9%) after 10,000 cycles at 10 Ag−1. The surface characteristics of metal oxide nanostructures and the efficient conductive networks of r-GO and GCN sheets are primarily responsible for the ternary α-Fe2O3/r-GO/GCN composite's superior electrochemical performance. Asymmetric supercapacitor (ASC) devices were constructed using 3D/2D/2D anodic material and activated carbon as a cathode material with a power density of 929 Wkg−1, energy density of 40 WhKg−1, and 92 % of capacity retention.

Alignment behavior of nerve, vascular, muscle, and intestine cells in two- and three-dimensional strategies.

By harnessing structural hierarchical insights, plausibly simulate better ones imagination to figure out the best choice of methods for reaching out the unprecedented developments of the tissue engineering products as a next level. Constructing a functional tissue that incorporates two-dimensional (2D) or higher dimensions requires overcoming technological or biological limitations in order to orchestrate the structural compilation of one-dimensional and 2D sheets (microstructures) simultaneously (in situ). This approach enables the creation of a layered structure that can be referred to as an ensemble of layers or, after several days of maturation, a direct or indirect joining of layers. Here, we have avoided providing a detailed methodological description of three-dimensional and 2D strategies, except for a few interesting examples that highlight the higher alignment of cells and emphasize rarely remembered facts associated with vascular, peripheral nerve, muscle, and intestine tissues. The effective directionality of cells in conjunction with geometric cues (in the range of micrometers) is well known to affect a variety of cell behaviors. The curvature of a cell's environment is one of the factors that influence the formation of patterns within tissues. The text will cover cell types containing some level of stemness, which will be followed by their consequences for tissue formation. Other important considerations pertain to cytoskeleton traction forces, cell organelle positioning, and cell migration. An overview of cell alignment along with several pivotal molecular and cellular level concepts, such as mechanotransduction, chirality, and curvature of structure effects on cell alignments will be presented. The mechanotransduction term will be used here in the context of the sensing capability that cells show as a result of force-induced changes either at the conformational or the organizational levels, a capability that allows us to modify cell fate by triggering downstream signaling pathways. A discussion of the cells' cytoskeleton and of the stress fibers involvement in altering the cell's circumferential constitution behavior (alignment) based on exposed scaffold radius will be provided. Curvatures with size similarities in the range of cell sizes cause the cell's behavior to act as if it was in an in vivo tissue environment. The revision of the literature, patents, and clinical trials performed for the present study shows that there is a clear need for translational research through the implementation of clinical trial platforms that address the tissue engineering possibilities raised in the current revision. This article is categorized under: Infectious Diseases > Biomedical Engineering Neurological Diseases > Biomedical Engineering Cardiovascular Diseases > Biomedical Engineering.

Versatile Bifunctional Ag@g-C3N4/r-GO Catalyst for Efficient Photo- and Electrocatalytic H2 Production

Here, we develop a series of hybrid Ag@g-C3N4/r-GO nanocomposite materials that are highly active, durable, and adaptable for electro- and photocatalytic H2 generation under visible light by employing a rapid and simple sonochemical technique. Multiple catalytic behaviors can be achieved through the strategic introduction of Ag metal into a hierarchical structure consisting of photo- and electroactive two-dimensional (2D) sheets with various band configurations. The outcomes of this work show the development of heterojunctions and show how electro- and photocatalysis were both synergistically improved. The fabricated materials were examined for photocatalytic hydrogen evolution, photoelectrocatalytic (PEC) hydrogen evolution, and electrocatalytic hydrogen evolution reaction (HER). In both photocatalytic conditions at 1.5 AM simulated light irradiation and electrocatalytic conditions, silver-doped composites showed better activity. Among all of the fabricated catalysts, the Ag20%@g-C3N4/r-GO (A20CNG) catalyst displayed the highest apparent quantum yield (AQY) of 1.69 and the highest hydrogen generation rate (954 μmol g–1 h–1). However, in the case of electrocatalysis, Ag15%@g-C3N4/r-GO (A15CNG) showed impressive HER activity with a low overpotential (η) of 0.484 V at 10 mA cm–2 current density with 130.6 mV dec–1 Tafel slope value and also exhibited approximately 16 times more current density than that of g-C3N4/GO (CNGO) at a fixed overpotential in the HER process; this was also supported by the electrochemical active surface area (ECSA). On the basis of the impressive results shown above, the Ag@g-C3N4/r-GO (ACNG) catalyst might be a promising and flexible nanocomposite for photo-, photoelectro-, and electrocatalytic hydrogen evolutions. This is the first study to our knowledge that provides the results of a comprehensive examination into the photo- and electrocatalytic application of an interesting and versatile bifunctional catalyst.

Converting Iron Corrosion Product to Nanostructured Conducting Polymers: Synthetic Strategies and Applications

ConspectusIron corrosion product, commonly known as rust, forms from the chemical reaction between iron and oxygen in the presence of water. It is a heterogeneous solid-state material composed of multiple phases and is ubiquitous throughout the universe. Sixteen distinct phases of iron corrosion product exist naturally under different temperature, pH, and pressure. Rust species such as hematite (α- Fe2O3), maghemite (γ-Fe2O3), goethite (α-FeOOH), and lepidocrocite (γ- FeOOH), first documented ca. 800 BCE, make up the solid-state chemical family composed of iron oxides, oxyhydroxides, and hydroxides. On an anthropogenic scale, rust represents a persistent problem to all manner of engineering and industrial pursuits. Corrosion is gradual and nondiscriminatory, affecting iron structures of all shapes and sizes from bridges and buildings to pipelines and wires that necessitates considerable spending on rust prevention and removal techniques. The infamous “Rust Belt” is colloquially used to describe regions of the United States characterized by sharp industrial decline and evokes images of derelict steel factories rusted over from decades of disuse. Therefore, iron corrosion product is commonly regarded as a symptom of deterioration and a physical manifestation of neglect in the eyes of the public. Yet, invaluable scientific potential exists within this “waste” material.Rust is thermodynamically stable, inexpensive, easily processable, and an abundant source of ferric ions (Fe3+) and therefore serves as an attractive oxidative candidate for developing chemical reactions. The ferric ion, with a standard reduction potential of +0.77 V, is an oxidizing agent that is well-investigated in the syntheses of highly conductive conjugated polymers such as poly(3,4-ethylenedioxythiophene) (PEDOT) and polypyrrole (PPy). Additionally, hydrolysis products of ferric ions form various nanostructures and provide diversified growing template for conducting polymers, including rod-shape akageneite (β-FeOOH), fiber-shape goethite (α-FeOOH), 2D sheet iron oxychloride (FeOCl), and spherical/cubic hematite (α-Fe2O3).In this Account, we introduce our unique synthetic strategies that involve rust and advance the state-of-the-art in chemical synthesis of nanostructured conducting polymers. We utilize products from rust, droplets with rust, and interfaces containing rust to synthesize nanostructured conducting polymer including rust-based vapor-phase polymerization (RVPP), aerosol vapor polymerization (AVP), and condensing vapor-phase polymerization (CVPP). Owing to the high conductivity and high surface area, nanostructured conducting polymers are emerging as hotspots for electrode materials in energy storage devices (i.e., supercapacitors) and solar cells. In the second part of this Account, we discuss how combining our unique synthetic strategies with conventional materials and fabrication techniques produces devices with high figure of merit performance. These devices include a brick supercapacitor as proof-of-concept energy storage masonry material, a 3D microsupercapacitor with a superior and low-cost electrode engineering strategy as well as high energy density larger than a thin-lithium battery, and a dye-sensitized solar cell with an efficiency superior to that of Pt with cost-effective fabrication.

Tuning the lattice thermal conductivity of bilayer penta-graphene by interlayer twisting

Penta-graphene (PG) is the well-known prototype of the extensively studied 2D pentagon-based materials in recent years, and twisting strategy has been widely used to tune the properties of 2D sheets since the discovery of superconductivity in twisted bilayer graphene. However, no study is reported on how twisting affects the phonon properties of such penta-sheets. In this work, for the first time, we study the effect of twisting on the phonon transport properties of PG by using density functional theory and the phonon Boltzmann transport equation combined with two-channel transport theory and machine learning method. It is found that the in-plane lattice thermal conductivity of the twisted bilayer PG with a twist angle of 36.87° is only 96.72 W/mK at 300 K, reduced by 77.16% as compared to that of untwisted bilayer PG, and the four-phonon interaction further reduces the thermal conductivity by nearly 36%, while the coherence contribution to the thermal conductivity is enhanced to 9.69 W/mK from 0.13 W/mK by twisting. These results indicate that interlayer twisting not only can enhance three- and four-phonon scattering but also can uplift phonon coherence due to the resulted complex atomic configuration and high anharmonicity in bilayer PG.

Point singularity array with metasurfaces

Phase singularities are loci of darkness surrounded by monochromatic light in a scalar field, with applications in optical trapping, super-resolution imaging, and structured light-matter interactions. Although 1D singular structures, like optical vortices, are common due to their robust topological properties, uncommon 0D (point) and 2D (sheet) singularities can be generated by wavefront-shaping devices like metasurfaces. With the design flexibility of metasurfaces, we deterministically position ten identical point singularities using a single illumination source. The phasefront is inverse-designed using phase-gradient maximization with an automatically-differentiable propagator and produces tight longitudinal intensity confinement. The array is experimentally realized with a TiO2 metasurface. One possible application is blue-detuned neutral atom trap arrays, for which this field would enforce 3D confinement and a potential depth around 0.22 mK per watt of incident laser power. We show that metasurface-enabled point singularity engineering may significantly simplify and miniaturize the optical architecture for super-resolution microscopes and dark traps.

A Significant Two-Dimensional Structural Transformation in a Coordination Polymer that Changes Its Electronic and Protonic Behavior.

A 2D-to-2D (2D: two-dimensional) structural transformation accompanying significant bond rearrangement and coordination environment change is demonstrated in a coordination polymer (CP) comprised of copper(II) ions and terephthalate (BDC2- ) ligands for the first time. When immersed in water, a free-standing membrane of 2D Cu(BDC)(DMF) (Cu-1; DMF: N,N-dimethylformamide) transforms into 2D Cu(BDC)(H2 O)2 (Cu-2) while maintaining its highly oriented layered structure. In the 2D sheet, paddlewheel-type CuII dimers coordinated with four bidentate BDC ligands in a square-planar array in Cu-1 were released to form uniform aqua-bridged CuII chains, which are cross-linked with each other by unidentate BDC ligands, in Cu-2. The present facile approach to implement the 2D-to-2D transformation accompanied by bond rearrangement, which is characteristic of CPs, leads to a marked increase in in-plane magnetic susceptibility and proton conductivity. In situ experiments in support of theoretical calculations unveiled the energy diagram that governs the unique structural transformation.

A Significant Two‐Dimensional Structural Transformation in a Coordination Polymer that Changes Its Electronic and Protonic Behavior

AbstractA 2D‐to‐2D (2D: two‐dimensional) structural transformation accompanying significant bond rearrangement and coordination environment change is demonstrated in a coordination polymer (CP) comprised of copper(II) ions and terephthalate (BDC2−) ligands for the first time. When immersed in water, a free‐standing membrane of 2D Cu(BDC)(DMF) (Cu‐1; DMF: N,N‐dimethylformamide) transforms into 2D Cu(BDC)(H2O)2 (Cu‐2) while maintaining its highly oriented layered structure. In the 2D sheet, paddlewheel‐type CuII dimers coordinated with four bidentate BDC ligands in a square‐planar array in Cu‐1 were released to form uniform aqua‐bridged CuII chains, which are cross‐linked with each other by unidentate BDC ligands, in Cu‐2. The present facile approach to implement the 2D‐to‐2D transformation accompanied by bond rearrangement, which is characteristic of CPs, leads to a marked increase in in‐plane magnetic susceptibility and proton conductivity. In situ experiments in support of theoretical calculations unveiled the energy diagram that governs the unique structural transformation.

Engineering the Electronic and Thermal Properties of Two-Dimensional Covalent Organic Frameworks

Two-dimensional covalent organic frameworks (2D COFs) are a class of modular polymeric crystals with high porosities and large surface areas. Their tunable microstructure (with a wide array of choices for the molecular building block) provides the opportunity for their bottom-up design and potentially tailorable physical properties. In this work, through combined density functional theory (DFT) calculations and molecular dynamics (MD) simulations, we study the influence of different molecular functional groups and varying porosities on the electronic and thermal properties of 2D COFs. More specifically, by performing DFT calculations on 24 different 2D COFs, we demonstrate that one of the main descriptors dictating their band gaps are their mass densities or network porosities. Furthermore, we also find that specific functional groups forming the nodes can lead to larger localization of charge densities resulting in wider band gaps. By performing MD simulations to investigate their thermal properties, we show that (similar to their electronic properties) mass density is also one of the main factors dictating heat conduction, where higher densities are associated with relatively higher thermal conductivities along the 2D sheets. Our spectral energy density calculations provide insights into the highly anharmonic nature of these materials. We find that increasing porosities lead to larger anharmonic interactions and thus reduced thermal conductivities in these materials. Similar to their electronic band gaps, the nodes forming the 2D COFs also have a significant contribution in dictating their thermal conductivities with bigger nodes (accompanied by higher densities) generally resulting in relatively higher thermal conductivities in 2D COFs. Taken together, the resulting changes in the electronic and thermal properties from variations in the building blocks in 2D COFs lend insights into fundamental changes in the microscopic thermodynamics that arise from systematically changing their molecular structure. Therefore, our study provides a blueprint for the strategic syntheses of 2D COFs with “user-defined” electronic and thermal properties that will ultimately aide in their incorporation into various applications.

Unveiling Superior Capacitive Behaviors of One-Pot Molten Salt-Engineered B, N Co-Doped Porous Carbon Sheets.

Heteroatom-doped porous carbon materials with distinctive surface properties and capacitive behavior have been accepted as promising candidates for supercapacitor electrodes. Currently, the researches mainly focus on developing facile synthetic method and unveiling the structure-activity relationship to further elevate their capacitive performance. Here, the B, N co-doped porous carbon sheet (BN-PCS) is constructed by one-pot pyrolysis of agar in KCl/KHCO3 molten salt system. In this process, the urea acts as directing agent to guide the formation of 2D sheet morphology, and the decomposition of KHCO3 and boric acid creates rich micro- and mesopores in the carbon framework. The specific capacitance of optimized BN-PCS reaches 361.1 F g-1 at a current density of 0.5 A g-1 in an aqueous KOH electrolyte. Impressively, the fabricated symmetrical supercapacitor affords a maximum energy density of 43.5Wh kg-1 at the power density of 375.0W kg-1 in 1.0mol L-1 TEABF4 /AN electrolyte. It also achieves excellent long-term stability with capacitance retention of 91.1% and Columbic efficiency of 100% over 10000 cycles. This study indicates one-pot molten salt method is effective in engineering advanced carbon materials for high-performance energy storage devices.

Mechanochemical Pretreated Mn+1AXn (MAX) Phase to Synthesize 2D-Ti3C2Tx MXene Sheets for High-Performance Supercapacitors.

Two-dimensional (2D) MXenes sheet-like micro-structures have attracted attention as an effective electrochemical energy storage material due to their efficient electrolyte/cation interfacial charge transports inside the 2D sheets which results in ultrahigh rate capability and high volumetric capacitance. In this article, Ti3C2Tx MXene is prepared by a combination of ball milling and chemical etching from Ti3AlC2 powder. The effects of ball milling and etching duration on the physiochemical properties are also explored, as well as the electrochemical performance of as-prepared Ti3C2 MXene. The electrochemical performances of 6 h mechanochemically treated and 12 h chemically etched MXene (BM-12H) exhibit an electric double layer capacitance behavior with an enhanced specific capacitance of 146.3 F g-1 compared to 24 and 48 h treated samples. Moreover, 5000-cycle stability tested sample's (BM-12H) charge/discharge show increased specific capacitance due to the termination of the -OH group, intercalation of K+ ion and transformation to TiO2/Ti3C2 hybrid structure in a 3 M KOH electrolyte. Interestingly, a symmetric supercapacitor (SSC) device fabricated in a 1 M LiPF6 electrolyte in order to extend the voltage window up to 3 V shows a pseudocapacitance behavior due to Li on interaction/de-intercalation. In addition, the SSC shows an excellent energy and power density of 138.33 W h kg-1 and 1500 W kg-1, respectively. The ball milling pre-treated MXene exhibited an excellent performance and stability due to the increased interlayer distance between the MXene sheets and intercalation and deintercalation of Li+ ions.

An automated, geometry-based method for hippocampal shape and thickness analysis

The hippocampus is one of the most studied neuroanatomical structures due to its involvement in attention, learning, and memory as well as its atrophy in ageing, neurological, and psychiatric diseases. Hippocampal shape changes, however, are complex and cannot be fully characterized by a single summary metric such as hippocampal volume as determined from MR images. In this work, we propose an automated, geometry-based approach for the unfolding, point-wise correspondence, and local analysis of hippocampal shape features such as thickness and curvature. Starting from an automated segmentation of hippocampal subfields, we create a 3D tetrahedral mesh model as well as a 3D intrinsic coordinate system of the hippocampal body. From this coordinate system, we derive local curvature and thickness estimates as well as a 2D sheet for hippocampal unfolding. We evaluate the performance of our algorithm with a series of experiments to quantify neurodegenerative changes in Mild Cognitive Impairment and Alzheimer’s disease dementia. We find that hippocampal thickness estimates detect known differences between clinical groups and can determine the location of these effects on the hippocampal sheet. Further, thickness estimates improve classification of clinical groups and cognitively unimpaired controls when added as an additional predictor. Comparable results are obtained with different datasets and segmentation algorithms. Taken together, we replicate canonical findings on hippocampal volume/shape changes in dementia, extend them by gaining insight into their spatial localization on the hippocampal sheet, and provide additional, complementary information beyond traditional measures. We provide a new set of sensitive processing and analysis tools for the analysis of hippocampal geometry that allows comparisons across studies without relying on image registration or requiring manual intervention.