ADVANCES OF GRAPHENE-BASED AEROGELS AND THEIR MODIFICATIONS IN LITHIUM-SULFUR BATTERIES

Lithium-sulfur (Li–S) batteries are the current focus of attention as candidates for next-generation energy storage systems due to their high energy density, low cost and environmental friendliness. However, their commercialization is hampered by various issues, including poor electrical conductivity of sulfur and its reduction products, low utilization of active material, limited sulfur loading and severe lithium polysulfides (LiPSs) shuttling effect. To solve these problems, various 0D, 1D and 2D nanostructured carbon materials with developed surface morphology, electrochemical stability and electrical conductivity have been examined for immobilizing sulfur, mitigating its volume variation and enhancing its electrochemical kinetics. Here we review the recent progress in design and fabrication of carbon-based sulfur hosts, free-standing cathodes, interlayers and functional separators for Li–S batteries using 3D graphene networks presented by graphene aerogels (GAs). The main characteristics of GAs and their synthesis routes are overviewed first. Further, the fabrication of both conventional slurry-casted cathodes and binder and current collector-free self-supporting sulfur composite cathodes based on pure and modified GAs acting as highly porous matrix for sulfur are discussed. In-depth analysis of the mechanisms of electrochemical reactions depending on the modifier type are provided. The advances of modified GAs in the design and preparation of interlayers and functional separators for Li–S batteries are deliberated as well. Finally, the conclusion and perspectives for future development of 3D nanostructured carbons for Li–S battery technology are offere

Nanofibrous biologically soluble scaffolds as an effective drug delivery system

In this article, the synthesis of biocompatible fibrous scaffolds with antimicrobial properties based on polycaprolactone/hydroxyapatite/amoxicillin and study of their surface morphology, antimicrobial effect, and drug release are discussed. Hydroxyapatite (1–2 $\mu$m, 97%) synthesized from biologically waste material (eggshell) was added to the composite scaffolds as a bone-replacement material. The scaffolds’ antimicrobial properties were evaluated against S. aureus and E. faecalis. The scaffolds possessed a sustained drug release from the scaffolds amounted to about 94% of the antibiotic’s total weight over a 4-week observation period. Agar diffusion confirmed the antimicrobial properties of the scaffolds against specific bacteria

Nanofibrous biologically soluble scaffolds as an effective drug delivery system

In this article, the synthesis of biocompatible fibrous scaffolds with antimicrobial properties based on polycaprolactone/hydroxyapatite/amoxicillin and study of their surface morphology, antimicrobial effect, and drug release are discussed. Hydroxyapatite (1–2 $\mu$m, 97%) synthesized from biologically waste material (eggshell) was added to the composite scaffolds as a bone-replacement material. The scaffolds’ antimicrobial properties were evaluated against S. aureus and E. faecalis. The scaffolds possessed a sustained drug release from the scaffolds amounted to about 94% of the antibiotic’s total weight over a 4-week observation period. Agar diffusion confirmed the antimicrobial properties of the scaffolds against specific bacteria

EFFECTIVENESS OF BIO-WASTE-DERIVED CARBON DOPING ON DE-ICING PERFORMANCE OF AN ELECTRICALLY RESISTANT CONCRETE

This paper proposes a modified carbon-based concrete filler composition, which can potentially be used as a self-de-icing pavement. Carbon fibers (CNFs), graphene-like porous carbon (GLC), and a CNF/GLC composite were developed to reinforce concrete with the aim to improve its electrical conductivity and mechanical properties. The effect of the CNF and GLC loadings on the electrical conductivity of the filled concrete was evaluated in a climatic chamber at temperatures simulating water-freezing conditions on a concrete road. The results show that even a negligible loading (0.2 wt.%) of concrete with CNF/GLC results in a dramatic decrease in its resistance when compared to the same loadings for CNF and GLC added separately. Depending on the number of fillers, the temperature of the modified concrete samples reached up to +19.8 °C at low voltage (10 V) at −10 °C, demonstrating the perspective of their heat output for anti-icing applications. Additionally, this study shows that adding 2.0 wt.% of the CNF/GLC composite to the concrete improves its compressive strength by 33.93% compared to the unmodified concrete

Об аэрогелях на основе углеродных наноматериалов

В обзорной статье представлены современные тенденции развития и применения углеродных наноматериалов и производных на их основе. Аэрогели на основе графена и других углеродных наноматериалов представляют собой класс сверхлегких веществ, в которых жидкая фаза полностью замещена газообразной. В свою очередь графеновый аэрогель получил название самого легкого материала, тем самым опередив рекорд аэрографита, долгое время сохранявшего за собой лидерство. Аэрогели характеризуются низкой плотностью, высокой удельной площадью поверхности и высоким показателем гидрофобности. Помимо этого, в зависимости от целей применения, аэрогели на основе углеродных наноматериалов могут проявлять магнитные и электропроводящие свойства, при этом сохраняя гибкость своей 3D структуры. Впечатляющие свойства новых нано материалов – аэрогелей, вызывают огромный интерес ученых для решения проблемы поиска их применения в различных областях, начиная от охраны окружающей среды до медицины и электроники. 

A MINI-REVIEW ON RECENT DEVELOPMENTS IN ANTI-ICING METHODS

An aggressive impact of the formed ice on the surface of man-made objects can ultimately lead to serious consequences in their work. When icing occurs, the quality and characteristics of equipment, instruments, and building structures deteriorate, which affects the durability of their use. Delays in the adoption of measures against icing endanger the safety of air travel and road traffic. Various methods have been developed to combat de-icing, such as mechanical de-icing, the use of salts, the application of a hydrophobic coating to the surfaces, ultrasonic treatment and electric heating. In this review, we summarize the recent advances in the field of anti-icing and analyze the role of various additives and their operating mechanisms

Influence of Metal Oxide Particles on Bandgap of 1D Photocatalysts Based on SrTiO3/PAN Fibers

This paper deals with the study of the optical properties of one-dimensional SrTiO3/PAN-based photocatalysts with the addition of metal oxide particles and the determination of their bandgaps. One-dimensional photocatalysts were obtained by the electrospinning method. Particles of metals such as iron, chromium, and copper were used as additives that are capable of improving the fibers’ photocatalytic properties based on SrTiO3/PAN. The optimal ratios of the solutions for the electrospinning of fibers based on SrTiO3/PAN with the addition of metal oxide particles were determined. The transmission and reflection of composite photocatalysts with metal oxide particles were measured in a wide range of spectra, from the ultraviolet region (185 nm) to near-infrared radiation (3600 nm), to determine the values of their bandgaps. Thus, the introduction of metal oxide particles resulted in a decrease in the bandgaps of the obtained composite photocatalysts compared to the initial SrTiO3/PAN (3.57 eV), with the following values: −3.11 eV for SrTiO3/PAN/Fe2O3, −2.84 eV for SrTiO3/PAN/CuO, and −2.89 eV for SrTiO3/PAN/Cr2O3. The obtained composite photocatalysts were tested for the production of hydrogen by the splitting of water–methanol mixtures under UV irradiation, and the following rates of hydrogen evolution were determined: 344.67 µmol h−1 g−1 for SrTiO3/PAN/Fe2O3, 398.93 µmol h−1 g−1 for SrTiO3/PAN/Cr2O3, and 420.82 µmol h−1 g−1 for SrTiO3/PAN/CuO

EFFECT OF GRAPHENE OXIDE/HYDROXYAPATITE NANOCOMPOSITE ON OSTEOGENIC DIFFERENTIATION AND ANTIMICROBIAL ACTIVITY

This paper presents the fabrication and characterization of electrospun graphene oxide/calcium hydroxyapatite/polycaprolactone composite. Polycaprolactone is well-known for its excellent medical property and chemo-resistance. On the other hand graphene oxide (GO) and calcium hydroxyapatite (HAp) are both known for their superior biocompatibility, high mechanical properties, considerable electrical and thermal conductivity. Under current research GO and HAp were synthesized from an abundant bio-wastes material. As-prepared GO/HAp composite was dispersed in biodegradable polymer – polycaprolactone (PCL) in order to device a composite scaffold with the purpose to enhance osteogenic differentiation of osteoblasts for potential medical application. Synthesised composite was characterised using various chemo-physical methods. Biocompatibility was tested in the cell proliferation assay with preosteoblasts MC3T3-E1 cell line in order to identify any cytotoxic effect caused by its compounds. The bacteriostatic effect of GO was assessed using Staphylococcus aureus and Escherichia coli bacterial strains. Obtained GO/HAp/PCL composite scaffold can serve as a biologically compatible matrix for potential bone tissue regeneration with antimicrobial effect; provides an excellent biological compatibility for prospective application in medicine and clinical dentistry

Modified Activated Graphene-Based Carbon Electrodes from Rice Husk for Supercapacitor Applications

The renewable biomass material obtained from rice husk, a low-cost agricultural waste, was used as a precursor to synthesize a highly porous graphene-based carbon as electrode material for supercapacitors. Activated graphene-based carbon (AGC) was obtained by a two-step chemical procedure and exhibited a very high specific surface area (SSA) of 3292 m2 g−1. The surface morphology of the synthesized materials was studied using scanning and transmission electron microscopy (SEM, TEM). Furthermore, the AGC was modified with nickel hydroxide Ni(OH)2 through a simple chemical precipitation method. It was found that the most significant increase in capacitance could be reached with Ni(OH)2 loadings of around 9 wt.%. The measured specific capacitance of the pure AGC supercapacitor electrodes was 236 F g−1, whereas electrodes from the material modified with 9 wt.% Ni(OH)2 showed a specific capacitance of up to 300 F g−1 at a current density of 50 mA g−1. The increase in specific capacitance achieved due to chemical modification was, therefore 27%