Carbon Trends最新文献

Free-standing electrode materials provide many desirable properties for electrochemical energy storage devices due to their light weight, good conductive capacity, excellent mechanical strength, high energy/power density and extraordinary electrochemical stability. Particularly, carbonaceous matrix nanomaterials, such as graphene materials, carbon nanotubes, carbon nanofibers, carbon papers and carbon cloths, play important roles in the free-standing electrodes, including serving as conducting network skeleton, loading electrochemically active material, enhancing mechanical toughness and flexibility, and preventing the structural damage during charge/discharge processes. In this review, we give a systematic overview of the state-of-the-art research progress on carbonaceous matrixes-based free-standing electrode materials for electrochemical energy storage, from synthesis methods, structural design, to important applications in flexible energy storage devices including lithium-ion batteries, lithium-sulfur batteries, sodium-ion batteries, lithium-oxygen batteries, and supercapacitors for each class of matrix-based electrode materials. In particular, the structure design strategies utilizing the advantages of free-standing matrixes to address the existing issues and improve the electrochemical and mechanical performance of energy storage devices are discussed in detail. At the end, we also discuss the challenges and demonstrate the prospective for the future development of such materials for advanced flexible energy storage devices.

A rectangular graphyne sheet is composed of units similar to phenyl rings that are linked by acetylenic chains, as in hexagonal $\gamma$-graphyne. This system is organized over a rectangular lattice similar to that of the recently synthesized biphenylene network. We investigate the stability of this layered material from different perspectives and study its electronic structure. Rectangular graphyne is a semiconducting system in its pristine form. It features a pair of highly localized states. These characteristics are correlated with the structural anisotropy of the system, since its frontier states behave like quasi-1D states embedded in the 2D lattice. We further consider modified systems in which longer acetylenic links are introduced. We discuss how a strategic choice of the position of these longer bridges leads to specific changes of the electronic structure of the rectangular graphyne sheet.

Poly(heptazine imide) (PHI), a carbon nitride polymer, is a highly efficient visible-light-driven photocatalytic material. We aimed to improve its photocatalytic performance for CO₂ conversion. We prepared M-PHIs by encapsulating different metals (M = K, Li, Rb, and Na) and H-PHIs, in which the metal of each M-PHI was ion-exchanged with a proton. We evaluated their photocatalytic activities for CO₂ conversion and found that Na-PHI and H-PHI, prepared from Na-PHI (H-PHI(NaCl)), showed more than twice the CO production efficiency of melon and other PHIs.

The high CO production efficiency of Na-PHI and H-PHI(NaCl) was attributed to their extremely smaller particle size compared with those of the other PHIs. By closely examining the synthesis conditions of Na-PHI, we have identified a method to intentionally synthesize M-PHI with small particle size. These results provide a new strategy for highly efficient CO₂ conversion using PHI.

Nefazodone, a derivative of triazolones, belongs to a group of heterocyclic aromatic compounds. It is used as an antidepressant for treating depression, including major depressive disorder. Unlike other antidepressant groups such as selective serotonin reuptake inhibitors, tricyclic antidepressants, or monoamine oxidase inhibitors, Nefazodone does not share chemical similarities. Recent research has focused on studying the reactivity and chemical structure influenced by Nefazodone's medicinal features in the drug's adsorption process on single-wall Carbon Nanotube (CNT) as an adsorbent in the gas phase using density functional theory (DFT), Becke, 3-parameter, Lee–Yang–Parr (B3LYP) 6-311+G(d,p) basis set (DFT/B3LYP/6-311+G(d,p)). The effect of electronegative atoms and phenyl groups on the adsorption of Nefazodone on CNT has been studied by calculating the adsorption energy for all active sites. On the other hand, thermodynamic values, such as Gibbs free energy (−4873.09 kJ), Enthalpy (−4872.83 kJ), and Entropy (903.09 J/mol.kelvin), as well as thermodynamic capacity (497.45 J/mol.kelvin), were calculated to show the reactivity of Nefazodone. The stability and reactivity were examined through the energies of the highest occupied molecular orbital (HOMO) (−5.53 eV) and lowest unoccupied molecular orbital (LUMO) (−0.58 eV) of Nefazodone, highlighting ten regions with chemical activity, all of which are thermodynamically stable. Some Electronic parameters such as chemical potential (µ), electronegativity (χ), softness (σ), hardness (η), and electrophilicity index (ω) were calculated. The comparison of chemical potential values between Nefazodone(−3.05 eV) and the more stable complex (−3.81 eV) illustrates the more reactivity for the complex. This suggests that Nefazodone can be transferred to biological systems through such an adsorption mechanism.

One of the most important concerns around the world nowadays is the drinking water quality. Silver ions (Ag⁺) are one of the heavy metal ions that can seriously degrade the water quality and therefore, the human health. Hence, the World Health Organization (WHO) fixed the maximum acceptable concentration of these ions in drinking water at approximately 0.93 µM. Thus, the development of cost-effective and efficient techniques and tools that can help to quantify Ag⁺ ions in drinking water is of great importance. Herein, we used a new, simple, eco-friendly and low-cost synthesis route to synthesize a sustainable hybrid carbon material, namely sulfonated reduced graphene oxide@graphene oxide (S-rGO@GO) that was utilized as electrode material for Ag⁺ ions electroanalysis in drinking water. The successful synthesis of S-rGO@GO was evidenced by XRD, Raman spectroscopy, XPS, FE-SEM and EDX. The electrochemical characterization of S-rGO@GO revealed its good affinities towards Ag⁺ and its good electron transport abilities. The sensor prepared from S-rGO@GO (S-rGO@GO/GCE) showed good repeatability and reproducibility. S-rGO@GO/GCE optimization revealed that its best performance is achieved when 5 µL of 1 mg/mL of S-rGO@GO suspension in ultrapure water is used for its fabrication and when the electrodeposition (Ag⁺ to Ag⁰) is carried out at -0.1 V vs. SCE for 200 s. The calibration of S-rGO@GO/GCE exhibited a linear relationship in the concentration range of 0.2 to 1.4 µM, with a sensitivity of (0.605 ± 0.015) µA/µM; the statistic LOD was found to be 0.0007 µM. Furthermore, S-rGO@GO/GCE has shown a great potential for real samples analysis.

Graphene research has developed quite rapidly partially because even a monatomic layer can be visualized with a conventional optical microscope. Although optical properties of multilayer graphene such as optical contrast, reflectance ($R$), and Raman scattering have been well studied, they are studied independently and the thickness dependence is limited to a rather thin region. In this paper, the evolution of optical properties by thickness from monolayer to multilayer graphene up to 107 nm thick is studied comprehensively. The empirically known change of color of multilayer graphene is confirmed from the R, G and B intensities extracted from the optical images. It is also found that, as far as $R$ for visible light is concerned, multilayer graphene is not necessarily considered as a layered material, and the refractive index for monolayer graphene is applicable even for the thickest multilayer graphene flake in this study. On the other hand, the layered structure and Raman scattering at each layer are essential to reproduce the G-band intensity of Raman scattering ($I_{\left(G\right)}$). Not only the multiple reflection but also the interference of scattered Raman light should be considered for $I_{\left(G\right)}$ of multilayer graphene thicker than $\sim$30 nm.

To meet the growing energy demand for large-scale applications, potassium-sulfur batteries (KSBs) have gained enormous attention owing to their high energy density, natural abundance, and specific capacity. Nevertheless, the shuttle effect, the insulating nature of sulfur, and the large volume change hinder the development of KSBs. To address the different challenges of KSBs, we report eco-friendly and biodegradable in-situ banana fiber-modified carbonized bacterial cellulose as a free-standing and binder-free cathode (sulfur) host. The catholyte K₂S₆ is used as active sulfur for cell fabrication owing to a high sulfur loading and even distribution of active material. However, introducing the catholyte induces the potassium side reaction by reacting to it. Therefore, carbonized bacterial cellulose is used as an interlayer to reduce the notorious polysulfide shuttle effect. As a result, the fabricated cell delivers a specific capacity of 437, 354, and 193 mAh g^-1 at the current density of 0.2, 0.7, and 1.2 C, respectively. During the long cycling, the cell shows excellent electrochemical performance for 200 cycles with a capacity retention of 78 % at 0.7 C. This work paves the way to utilize an eco-friendly and cost-effective approach to fabricate a high-performance KSB.

The controlled release of antibiotics is crucial to improving antimicrobial efficacy, reducing the risk of bacterial resistance, and ensuring a localized therapeutic effect. In this work, In-vitro Gentamicin release was studied using fluorescence chitosan collagen-cerium hydroxyapatite nanocomposites. Cerium-hydroxyapatite nanoparticles were synthesized using the hydrothermal method, and the nanocomposites were prepared by mixing chitosan-collagen-cerium hydroxyapatite at different weight ratios. Structural characterization was conducted using scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, and fluorescence microscopy. Ultraviolet–visible spectroscopy (UV–Vis) was used to quantify the release of gentamicin in simulated body fluid. Results showed that hydroxyapatite releases 90 % of gentamicin in the first 10 min, and the Chitosan-collagen-cerium hydroxyapatite nanocomposites release 80 % of gentamicin after 2 h. The antibacterial activity was studied against Escherichia coli (E. coli) at different time intervals. These nanocomposites can potentially improve the performance of biomedical applications.

Nanofibers are extremely thin fibers produced from materials such as carbon, polymers, ceramics, and metals with diameters in the nanometer range that gained significant interest due to their unique properties. Carbon nanotubes, which could be considered the most popular fibers in the nanoscale, have gained widespread recognition primarily due to their remarkable strength derived from their cylindrical hexagonal lattice formed by carbon covalent bonds. Here, a new family of carbon nanofibers is proposed, arising from the combination of the tubular hexagonal configuration of carbon nanotubes and the spherical nanostructure of carbon fullerenes. These novel nanofibers, hereafter named carbon nanotuballs, are expected to demonstrate new advantaged characteristics such as better cross-section properties, enhanced interfacial interactions, and other unique physical attributes when used as fillers within other phases. Some preliminary theoretical investigations based on molecular dynamics are provided here to test the structural stability and mechanical behaviour of some single-walled carbon nanotuballs.

Diamond growth from Chemical Vapor Deposition (CVD) on foreign substrates can require different pretreatment not only to improve the film nucleation but also to assure its adhesion by decreasing the expected film/substrate interface stress. To improve boron-doped film nucleation, growth, and adherence, different substrate pretreatments have been used mainly from the seeding process with diamond powder at various particle sizes. Despite this, the development of diamond growth on a Ti mesh remains difficult because of the requirement of a cohesive film to cover a 3D macroporous sample with varying growth rates based on its distinct network geometry. Then, this work describes a novel approach to growing boron-doped diamond (BDD) and boron-doped ultrananocrystalline diamond (B-UNCD) on titanium dioxide nanotubes (TDNT) produced simultaneously on both sides of Ti mesh by an anodization process. The films were obtained from two-step growth processes by assuring the entire diamond overlay on both TDNT/Ti mesh sides, including their outer/inner surfaces, as a 3D sample. TiO₂ - TiC conversion has dominated the renucleation process, facilitating the nanometric scale control. The film morphologies were systematically analyzed by FEG-SEM images at different sample planes and depths for both sample sides at different stages of film growth. The unique morphology of titania nanotubes associated with columnar and/or renucleation development of BDD, considering the film defects and valley, can systematically increase the electrode specific area. Raman spectra showed the film quality and its micro and/or ultrananodiamond structure and the boron doping features. Also, this growth process allowed a dopant-controlled adjustable conductivity. Then, the boron doping levels for both films were evaluated from Mott-Schottky plots at around 10¹⁹ Bcm⁻³, characterizing them with good conductivity. In addition, electrochemical measurements from Cyclic Voltammetry (CV) confirmed the expected diamond response on redox pair following the quasi-reversible criteria as high-performance diamond electrodes and in situ Raman spectroelectrochemical measurements assessed the stability of samples during electrochemical measurements, ensuring structural integrity. Finally, the samples were applied to the degradation of methylene blue, proving to be superior materials for electrochemical applications due to their advantages compared to those of similar 2D electrodes.