Showing papers in "Journal of Materials Science in 2020"
TL;DR: In this paper, the authors present an up-do-date review on natural fiber and resin types and sources, modification and processing techniques, physical and mechanical behaviors, applications, life-cycle assessment, and other properties of green composites.
Abstract: There has been much effort to provide eco-friendly and biodegradable materials for the next generation of composite products owing to global environmental concerns and increased awareness of renewable green resources. An increase in the use of natural materials in composites has led to a reduction in greenhouse gas emissions and carbon footprint of composites. In addition to the benefits obtained from green materials, there are some challenges in working with them, such as poor compatibility between the reinforcing natural fiber and matrix and the relatively high moisture absorption of natural fibers. Green composites can be a suitable alternative for petroleum-based materials. However, before this can be accomplished, there are a number of issues that need to be addressed, including poor interfacial adhesion between the matrix and natural fibers, moisture absorption, poor fire resistance, low impact strength, and low durability. Several researchers have studied the properties of natural fiber composites. These investigations have resulted in the development of several procedures for modifying natural fibers and resins. To address the increasing demand to use eco-friendly materials in different applications, an up-do-date review on natural fiber and resin types and sources, modification and processing techniques, physical and mechanical behaviors, applications, life-cycle assessment, and other properties of green composites is required to provide a better understanding of the behavior of green composites. This paper presents such a review based on 322 studies published since 1978.
393 citations
TL;DR: In this paper, a review of recent progress in the mechanical, thermal and interfacial properties of graphene/CNT multiphase polymer composites is examined, highlighting the improvements in two-and three-phase composites, owing to the addition of graphene and CNT.
Abstract: In this review, recent progress in the mechanical, thermal and interfacial properties of graphene/CNT multiphase polymer composites is examined. Progress in the mechanical and thermal properties of CNT (1D) and graphene (2D) nanostructure materials is also reviewed and compared. Furthermore, this review highlights the improvements in the mechanical, thermal and interfacial properties of two- and three-phase composites, owing to the addition of graphene/CNT. In particular, analysis of several notable papers on hybrid composites (graphene/CNT) provides an intensive review of synergetic effects on the overall properties of the corresponding composites. This holistic review describes an improved interface between fibers and a nanofiller-reinforced matrix. Although the presence of nanofillers even at low loadings confers an overall improvement in composite properties, the exact ratios of individual fillers and combined forms remain to be discussed in depth. Finally, potential applications, current challenges and future perspectives for use of these multiphase composites are discussed with regard to their extraordinary capabilities and promising developments in graphene/CNT family-based composite materials.
215 citations
TL;DR: In this article, the authors review some of the factors that influence the hardness of polycrystalline materials with grain sizes less than 1 µm and find evidence for a transition from dislocation-based plasticity to grain boundary sliding, rotation, or diffusion as the main mechanism responsible for hardness.
Abstract: We review some of the factors that influence the hardness of polycrystalline materials with grain sizes less than 1 µm. The fundamental physical mechanisms that govern the hardness of nanocrystalline materials are discussed. The recently proposed dislocation curvature model for grain size-dependent strengthening and the 60-year-old Hall–Petch relationship are compared. For grains less than 30 nm in size, there is evidence for a transition from dislocation-based plasticity to grain boundary sliding, rotation, or diffusion as the main mechanism responsible for hardness. The evidence surrounding the inverse Hall–Petch phenomenon is found to be inconclusive due to processing artefacts, grain growth effects, and errors associated with the conversion of hardness to yield strength in nanocrystalline materials.
211 citations
TL;DR: In this article, the authors highlight the general features of supported M-NPs as catalysts with particular attention to copper, gold, platinum, palladium, ruthenium, silver, cobalt and nickel and their catalytic evaluation in various reactions.
Abstract: Supported metal nanoparticles, M-NPs, are of great scientific and economic interest as they encompass application in chemical manufacturing, oil refining and environmental catalysis. Oxidation and hydrogenation reactions are among the major reactions catalyzed by supported M-NPs. Although supported M-NPs are preferable due to their easy recovery and reuse, there are still some practical issues regarding their catalytic activity and deactivation. This review highlights the general features of supported M-NPs as catalysts with particular attention to copper, gold, platinum, palladium, ruthenium, silver, cobalt and nickel and their catalytic evaluation in various reactions. The catalytic performance of noble M-NPs has been explored extensively in various selective oxidation and hydrogenation reactions. In general, noble metals are expensive and sensitive to poisons. Despite their significant merits and potential (easily available, comparatively inexpensive and less sensitive to poisons), catalysis by base M-NPs is relatively less explored. Therefore, activity of base M-NPs can be improved, and still, there is potential for such catalysts.
178 citations
TL;DR: In this paper, the experimental and theoretical achievements of seven kinds of thermoelectric materials, including BiTe series, SnSe series, CuSe series and Graphdiyne series, were reviewed.
Abstract: Thermoelectric materials are capable of converting heat and electricity to each other Thermoelectric devices can be miniaturized and highly integrated with existing semiconductor chip systems with microgenerators or microrefrigerators After years of research and accumulation, BiTe series, SnSe series, CuSe series, half-Heusler series, multicomponent oxides series, organic–inorganic composites series, and GeTe/PbTe series have been found to have excellent thermoelectric properties According to theoretical calculation, when the diameter of Bi2Te3 nanowires is 5 A, the ZT value reaches 14, and graphdiyne has a ZT value of 48 at 300 K Experimental measurements revealed that the ZT value of n-type SnSe reached 28 This review would focus on the updated experimental and theoretical achievements of seven kinds of materials, including BiTe series, SnSe series, CuSe series, multicomponent oxides, half-Heusler alloys, organic–inorganic composites, and GeTe/PbTe series The preparation method, microstructure characteristics, device structure, and thermoelectric properties of each material will be described in detail By analyzing the performance of these materials, three possible development directions are put forward for how to further improve the thermoelectric properties of materials
150 citations
TL;DR: In this article, the authors discuss the recent advances and progress on the utilization of functionalized graphene, graphene oxide, and its derivatives for effective storage of hydrogen, along with important theoretical advancements via DFT calculations, first-principle calculations, and Monte Carlo Simulations, etc.
Abstract: With growing demands of energy and enormous consumption of fossil fuels, the world is in dire need of a clean and renewable source of energy. Hydrogen (H2) is the best alternative, owing to its high calorific value (144 MJ/kg) and exceptional mass-energy density. Being an energy carrier rather than an energy source, it has an edge over other alternate sources of energy like solar energy, wind energy, and tidal energy, which require a constant energy source dependent upon weather conditions. However, its utilization as an energy carrier has not yet been commercialized due to its poor storage performance, which is attributed to low gravimetric and volumetric densities of adsorbed hydrogen at ambient temperature and technological limitations in meeting the stringent parameters set by Department of Energy, USA. With exceptionally large surface area (2630 m2/g), porous nature, lightweight, and high chemical and thermal stability (melting point ~ 4510 K) along with the possibility of economical and scalable production, graphene-based solid-state porous materials have shown promising applications in efficient hydrogen storage. In this context, the present review discusses the recent advances and progress on the utilization of functionalized graphene, graphene oxide, and its derivatives for effective storage of hydrogen, along with important theoretical advancements via DFT calculations, first-principle calculations, and Monte Carlo Simulations, etc. Pristine graphene has poor hydrogen storage characteristics, and addition of dopants like boron and nitrogen or decoration by transition metals significantly improves the performance. In addition, graphene allows the tuning of surface curvature which can help in achieving a reversible hydrogen storage system with fast kinetics. The impact of external stimuli like electric field and strain on electronic structure of graphene is discussed with the applicability in achieving a highly controllable adsorption–desorption system. Finally, the review concludes with life cycle assessment of graphene-engineered composites for effective hydrogen storage applications, along with their energy and environmental implications.
120 citations
TL;DR: In this article, the authors proposed a step forward to expand HECs to compositionally complex ceramics (CCCs) to include medium-entropy and non-equimolar compositions and further considered the complexities of aliovalent cations and anion vacancies as well as ordered structures with two cation sublattices.
Abstract: High-entropy ceramics (HECs) have quickly gained attention since 2015. To date, nearly all work has focused on five-component, equimolar compositions. This perspective article briefly reviews different families of HECs and selected properties. Following a couple of our most recent studies, we propose a step forward to expand HECs to compositionally complex ceramics (CCCs) to include medium-entropy and non-equimolar compositions. Using defective fluorite and ordered pyrochlore oxides as two primary examples, we further consider the complexities of aliovalent cations and anion vacancies as well as ordered structures with two cation sublattices. Better thermally insulating yet stiff CCCs have been found in non-equimolar compositions with optimal amounts of oxygen vacancies and in ordered pyrochlores with substantial size disorder. It is demonstrated that medium-entropy ceramics can prevail over their high-entropy counterparts. The diversifying classes of CCCs provide even more possibilities than HECs to tailor the composition, defects, disorder/order, and, consequently, various properties.
112 citations
TL;DR: In this paper, the current developments of metal/metal oxide decorated graphene (MGr) composites in the field of electrochemical capacitors are elucidated on account of their synergistic properties.
Abstract: Metal/metal oxides and conductive polymers are common supercapacitor electrode materials, revealing high power density as well as long cycle life. In composites, graphene and metal oxides displayed the combination of the excellent cycle stability of graphene and the high-capacity properties of metal oxides which remarkably improve the comprehensive properties of nanocomposites. The current developments of metal/metal oxide decorated graphene (MGr) composites in the field of electrochemical capacitors are elucidated here on account of their synergistic properties. It is demonstrated that, in comparison with their individual influences, MGr composites have attained substantial improvement in rate capability, capacity, and cycling stability. Mainly, an overview of the characteristics, preparation approaches, and application of graphene (Gr) is outlined. Mechanism of different types of electrochemical capacitance is described explicitly. Finally, the future prospects and challenges of MGr composites have been discussed for energy storage.
95 citations
TL;DR: In this paper, a carbon-supported hollow heterostructure MoS2@Mo2C composite was constructed via two-step calcination and sulfurized process from carbonized Mo2C-Mo3C2 heteronanowires.
Abstract: Non-precious metal-based electrocatalyst with high activity and stability for efficient hydrogen evolution reaction (HER) is of critical importance toward low-cost and large-scale water splitting. Traditional MoS2 has electrocatalytic hydrogen evolution inertness in alkaline environment, which is detrimental to the adsorption and dissociation of water. Composited with electrocatalyst with good electrical conductivity can enhance its HER activity. In this work, we for the first time construct a carbon-supported hollow heterostructure MoS2@Mo2C composite via two-step calcination and sulfurized process from carbonized Mo2C–Mo3C2 heteronanowires. The results show that the existence of the Mo3C2 phase is the key point to construct the effective heterostructure with hollow morphology. Due to the strong negative hydrogen binding energy for H on surface of Mo2C, the H+ reduction in the MoS2@Mo2C in the Volmer step can be enhanced. Compared with MoS2, MoS2@Mo2C has high electrocatalytic activity for hydrogen evolution with an onset potential of 28 mV, overpotential of 129 mV at the current density of 10 mA cm−2, a small Tafel slope of 78 mV dec−1, and an excellent stability. This work will provide new insights into the design of high-efficiency HER catalysts via interfacial engineering at nanoscale for commercial water splitting.
91 citations
TL;DR: In this paper, the role of cerium in forming stable, highmelting-point compounds, improving strength and thermal stability is analyzed along with its function as a grain refiner in the aluminum melt, the eutectic modifier, as de-gasifying and de-slagging agent through its reaction with gas and liquid impurities.
Abstract: Rare-earth metals create unique opportunities in improving properties of aluminum alloys. For over a century, there have been attempts to explore cerium for aluminum alloying, emphasizing advantages it exhibits among rare earths. This review covers laboratory and industrial efforts of applying cerium for a purpose of developing aluminum alloys with superior properties. The binary Al–Ce, ternary Al–Ce–X and higher-order phase systems are reviewed with a focus on the aluminum-rich sections. The role of cerium in forming stable, high-melting-point compounds, improving strength and thermal stability is analyzed along with its function as a grain refiner in the aluminum melt, the eutectic modifier, as de-gasifying and de-slagging agent through its reaction with gas and liquid impurities. In addition to conventional alloys with cerium as a minor and major ingredient also amorphous alloys along with aluminum matrix nanocomposites, exploring cerium oxide as reinforcement, are assessed. The role of cerium in bulk alloying is expanded to surface engineering solutions enhancing aluminum wear and corrosion resistance. Efforts of cerium recovery from parts after end of service life and alloy design for a recycling friendly world are discussed to minimize losses and prevent contamination of material supply chain in modern manufacturing.
86 citations
TL;DR: A review of the emerging field of giant piezoresistivity can be found in this article, where the authors focus on the inherent piezorestivity that occurs without irreversible resistivity changes, defined as the fractional change in resistance per unit strain.
Abstract: Piezoresistivity is an electromechanical effect characterized by the reversible change in the electrical resistivity with strain. It is useful for electrical-resistance-based strain/stress sensing. The resistivity can be the volumetric, interfacial or surface resistivity, though the volumetric resistivity is most meaningful scientifically. Because the irreversible resistivity change (due to damage or an irreversible microstructural change) adds to the reversible change that occurs at lower strains, the inclusion of the irreversible effect makes the piezoresistivity appear stronger than the inherent effect. This paper focuses on the inherent piezoresistivity that occurs without irreversible resistivity changes. The effect is described by the gage factor (GF), which is defined as the fractional change in resistance per unit strain. The GF can be positive or negative. Strong piezoresistivity involves the magnitude of the fractional change in resistivity much exceeding the strain magnitude. The reversible effect of strain on the electrical connectivity is the primary piezoresistivity mechanism. Giant piezoresistivity is characterized by GF ≥ 500. This critical review with 209 references covers the theory, mechanisms, methodology and status of piezoresistivity, and provides the first review of the emerging field of giant piezoresistivity. Piezoresistivity is exhibited by electrically conductive materials, particularly metals, carbons and composite materials with conductive fillers and nonconductive matrices. They include functional and structural materials. Piezoresistivity enables structural materials to be self-sensing. Unfortunately, GF was incorrectly or unreliably reported in a substantial fraction of the publications, due to the pitfalls systematically presented here. The most common pitfall involves using the two-probe method for the resistance measurement.
TL;DR: In this paper, the phase structures, morphologies, chemical compositions, and optical adsorption properties of the In2O3/WO3 heterostructured photocatalyst were characterized in detail.
Abstract: To effectively decompose the organic dyes in wastewater, a novel all-solid state Z-scheme In2O3/WO3 heterostructured photocatalyst was successfully prepared by loading In2O3 nanoparticles onto WO3 nano-needles through a two-step hydrothermal–solvothermal method. The phase structures, morphologies, chemical compositions, and optical adsorption properties of these photocatalysts were characterized in detail. In the Z-scheme photocatalytic system, the built-in internal electric field can accelerate the recombination of useless photo-generated holes on the VB of In2O3 and electrons on the CB of WO3. The retaining photo-generated charge carriers on the CB of In2O3 and VB of WO3 possess strong redox ability. Therefore, the In2O3/WO3 heterogeneous photocatalysts exhibited remarkably improved photocatalytic activity toward degradation of organic dyes and tetracycline hydrochloride compared to pure WO3 and In2O3 semiconductor materials under visible-light irradiation. The recycling experiments showed that Z-scheme In2O3/WO3 heterogeneous photocatalyst could still degrade 86.6% of methylene blue and 86.4% of rhodamine B even after three cycles, confirming its high photo-stability. The trapping experiments demonstrated that photo-generated holes and ·O2− were the predominant active species for photocatalytic degradation of organic dyes. Based on the experimental results, a possible photocatalytic mechanism of Z-scheme In2O3/WO3 heterostructure was proposed. This investigation provided a novel approach for construction of efficient heterostructured photocatalysts for wastewater purification.
TL;DR: In this article, the synthesis, properties and applications of polyaniline-based nanocomposites have been described with suitable examples centring on the role of nano-confinements and chemical modification along with existing challenges for commercial uses.
Abstract: In this review article, synthesis, properties and applications of polyaniline-based nanocomposites (PANI-NCs) have been described. Different methods (viz chemical, electrochemical, photochemical and mechano-chemical) and size confinement tools used for preparation of PANI-NC are described with their advantageous and disadvantageous features. On the basis of synergized electrical, magnetic, optical, mechanical and thermoelectric properties, PANI-NCs are used in development of sensors, support catalysts, water purifications, energy and biomedicals. Further, applications of PANI-NC are elaborated with suitable examples centring on the role of nano-confinements and chemical modification along with existing challenges for commercial uses.
TL;DR: In this article, the authors focus on the recent progress with respect to the advantages, common synthetic approaches and enhancement strategies of Fe, Co and Ni-based phosphides, with important works in each section elaborately introduced for researchers in the relevant area.
Abstract: Hydrogen fuel receives worldwide attention for the zero emission and high energy density. Production of hydrogen by electrochemical water splitting requires efficient electrocatalysts to boost the hydrogen evolution reaction (HER). Transition metal phosphides are regarded as promising substitutes for precious metals as HER electrocatalysts. This review focuses on the recent progress with respect to the advantages, common synthetic approaches and enhancement strategies of Fe, Co and Ni-based phosphides, with important works in each section elaborately introduced for researchers in the relevant area. After the rational design and fabrication, Fe, Co and Ni-based phosphides can become highly efficient, durable and cost-effective electrocatalysts, and thereby exhibit a great potential for the scale-up production of hydrogen fuel.
TL;DR: In this article, the effect of Ga content on magnetic properties of 30-wt% BaFe12−xGaxO19/epoxy(x = 0.1, 0.3 and 0.2) composites has been investigated.
Abstract: The article reports about the effect of Ga content on magnetic properties of 30 wt% BaFe12−xGaxO19/epoxy(x = 0.1, 0.3, 0.6, 0.9 and 1.2) composites with uniform and aligned (due to the action of external magnetic field under preparation) distribution of hexaferrite filler in epoxy matrix. The XRD investigations of BaFe12−xGaxO19/epoxy (x = 0.1, 0.3, 0.6, 0.9 and 1.2) composites have revealed that the alignment degree of a crystalline hexaferrite phase with a hexagonal unit cell of crystal structure and P63/mmc space group in composites with uniform filler distribution is near 0.5 and for the composites with aligned filler distribution it is 1 for the direction along the applied magnetic field and it is 0 for the direction across the applied magnetic field, respectively. The investigation of the hysteresis loops of BaFe12−xGaxO19/epoxy (x = 0.1–1.2) composites with the aligned distribution of filler for both directions to the applied magnetic field has shown that magnetic properties across the alignment direction are superior in comparison with similar measurements taken on composites with uniform filler distribution. It was shown that anisotropy of magnetic properties of BaFe12−xGaxO19/epoxy (x = 0.1–1.2) composites is observed for all the investigated composites with the aligned distribution of the filler. Squareness ratio Ms along/Ms across decreases with Ga content increase, while the value Hc along/Hc across approaches to 1. Such behavior of magnetic characteristics of the investigated composites indicates clearly the decrease in magnetocrystalline anisotropy of Ga-substituted hexaferrite under Ga content increase.
TL;DR: In this paper, hierarchical porous carbon was successfully synthesized from most abundant biomass onion peel via double crucible method and it was explored as renewable carbon source for low-cost energy storage device.
Abstract: Agro-waste-derived porous carbon has received more attention as electrode material for high-performance supercapacitor application due to its diversity and reproducibility. Herein, hierarchical porous carbon was successfully synthesized from most abundant biomass onion peel via double crucible method and it was explored as renewable carbon source for low-cost energy storage device. The supercapacitor electrode exhibits high specific capacitance of 127 Fg−1 at the current density of 0.75 Ag−1 with capacitance retention of 109% after 2000 cycles in three-electrode system. More importantly, its symmetric supercapacitor device exhibits energy density of 13.61 Wh kg−1 at the power density of 200.8 W kg−1 with remarkable electrochemical stability revealing capacitance retention above 100% over 14000 cycles. Our study demonstrates that onion peel-derived carbon is suitable for future low-cost energy storage device.
TL;DR: In this article, the formation mechanism and factors affecting electronic conductivity in doped ceria are clearly described, and two kinds of methods including the optimization of the single ceria-doped electrolyte and the use of the various electron blocking layers are systematically summarized.
Abstract: Ceria-based solid oxide fuel cells (SOFCs) are the promising candidates for the low- and intermediate-temperature SOFCs. However, the Ce4+ in the ceria-based electrolyte materials is likely reduced to Ce3+ under low oxygen partial pressure, leading to high electronic conductivity. Therefore, ceria-based SOFCs commonly show low open-circuit voltage and low efficiency due to the leakage current. While extensive studies of the electron transport mechanism and the methods for the prevention of leakage current in ceria-based electrolytes have been conducted, systematic reviews of the relevant literature have been notably rare. In this review, the formation mechanism and factors affecting electronic conductivity in doped ceria are clearly described. Additionally, two kinds of methods including the optimization of the single ceria-doped electrolyte and the use of the various electron blocking layers (e.g., ZrO2-based, doped BaCeO3/SrCeO3 and doped Bi2O3 materials) are systematically summarized. Finally, mathematical models describing the electrochemical characteristics of ceria-based SOFCs based on different assumptions are reviewed. This review can provide useful guidance for the further development and application of internal short-circuit-free ceria-based SOFCs.
TL;DR: In this paper, the results of an investigation into a microstructure formation on a wire-feed electron beam additive manufactured "steel-copper" bimetallic sample were revealed.
Abstract: This paper describes the results of an investigation into a microstructure formation on a wire-feed electron beam additive manufactured “steel–copper” bimetallic sample. The peculiarities of a gradient zone structure with a smooth change of components’ concentration are revealed. The heterogeneity of copper and steel distribution in the gradient zone is provided by copper solidification and precipitation mechanisms. Both solidification of coarse copper inclusions in the interdendrite areas or along the dendrite boundaries and precipitation of fine Cu-based particles at the cooling stage from the solid solution of Cu in γ-Fe are the main factors of structure formation during the double wire gradient zone deposition. The presence of such fine copper precipitates from the supersaturated solid solution was revealed by means of transmission electron microscopy. The shape of copper particles in the gradient zone varies from spherical to oblong and irregular. The shape of steel particles and/or grains is mainly determined by the peculiarities of the crystallization zone and is characterized by the primary crystallization of γ-iron dendrites from the liquid melt. A physical scheme describing a variation in phase composition and microstructure in gradient zone of the bimetallic specimen was proposed.
TL;DR: The technology of bio-printing has got validated for bone and skin tissue fabrication, and it is hoped that other tissues could be produced by this technique.
Abstract: The ultimate prospect of tissue engineering is to create autologous tissue grafts for future replacement therapies through utilization of cells and biomaterials simultaneously. Bio-printing is a novel technique, a growing field that is leading to the global revolution in medical sciences that has gained significant attention. Bio-printing has the potential to be used in producing human engineered tissues like bone and skin which then ultimately can be used in the clinics. In this paper, the 3D bio-printing applications of the engineered human tissues that are available (skin and bone) are reviewed. It is evident that various tissue engineering techniques have been applied in the fabrication of skin tissue; therefore, it leads to introduce tissue substitutes such as complementary, split-thickness skin graft, allografts, acellular dermal substitutes and cellularized graft-like commercial products, i.e., Dermagraft and Apligraf. Also, some bone scaffolds based on hydroxyapatite and biphasic calcium phosphate are available in the market. The technology of bio-printing has got validated for bone and skin tissue fabrication, and it is hoped that other tissues could be produced by this technique.
TL;DR: In this paper, a melamine phenylhypophosphonate named as MABP was synthesized to improve the flame retardancy and smoke suppression of epoxy resin.
Abstract: In order to improve the flame retardancy and smoke suppression of epoxy resin (EP) simultaneously, we synthesized a melamine phenylhypophosphonate named as MABP via a simple one-step method and used it to modify EP materials As expected, the addition of MABP not only largely improved the flame retardancy but also restrained the smoke release of EP For details, when the content of MABP was 10 wt%, the EP composite possessed a limiting oxygen index value of 33% and achieved to a UL-94 V-0 rating as well as its PHRR, THR and TSP values decreased by 551%, 271% and 60% compared with that of neat EP, respectively In addition, the flame-retardant mechanism was investigated by multiple instruments, and the corresponding results exhibited that the MABP could improve the compactness of char layer in condense phase and exerted fire-inhibition effect in gaseous phase
TL;DR: In this paper, a novel magnetic nanocomposite based on aromatic polyamide as a statistical star polymer was designed, characterized and studied in hyperthermia process of cancer therapy.
Abstract: In this work, a novel magnetic nanocomposite based on aromatic polyamide as a statistical star polymer was designed, characterized and studied in hyperthermia process of cancer therapy. The polymerization reaction was carried out via surface modification of magnetic nanoparticles (Fe3O4 MNPs) using polymerization process by phenylenediamine derivatives and terephthaloyl chloride. Various analytical techniques such as field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy, energy-dispersive X-ray, thermogravimetric and vibrating-sample magnetometer analyses were used to confirm the structure of the prepared nanocomposite. A unique rose flower and sphere morphologies were observed by FE-SEM images by the result of polymerization process and fabrication of the synthetic polymeric strands on the surface of the modified Fe3O4 magnetic cores. The application of this novel magnetic nanocomposite was evaluated in hyperthermia process as a potential method for cancer therapy and its exposure to an external alternating magnetic field. The highest specific absorption rate measured for 0.5 mg/mL of a sample was 191.97 w g−1, and the saturation magnetization value was 4.3 emu g−1.
TL;DR: In this article, a review of all-solid-state Li-ion batteries (ASSLIBs) has been presented, where the authors have discussed the architecture of ASSLIBs, advantages and characteristics of the solid polymer electrolytes.
Abstract: All-solid-state batteries are swiftly gaining the attention of the research community owing to their widespread applications in electric vehicles, digital electronics, portable appliances, etc. A battery comprises three components: cathode, anode and electrolyte. An electrolyte is the heart of the battery and plays a crucial role in the overall performance of the battery. In order to make the review more focused, all-solid-state Li-ion batteries (ASSLIBs) have been considered. This review covers the architecture of ASSLIBs, advantages, and characteristics of the solid polymer electrolytes. The important preparation methods are summarized, followed by the characterizations for testing the suitability of electrolytes for solid-state batteries. The discussion is focused on the ‘state of the art’ in the field of solid-state batteries, device fabrication, and comparison in terms of capacity, energy density, and cyclic stability. In the last section, the ion conduction mechanism in different solid polymer electrolytes is discussed. Finally, it is tried to give a possible outlook for developing future hybrid and multifunctional electrolytes which can act as a bridge for developing solid-state batteries covering a broad range of applications.
TL;DR: In this article, the authors proposed a method for preparing subtle and complex lattice structure Al2O3 ceramic via digital light processing (DLP) 3D printing technology, which achieved high porosity and high density without significant pores and cracks sintered ceramic.
Abstract: This paper proposed a method for preparing subtle and complex lattice structure Al2O3 ceramic via digital light processing (DLP) 3D printing technology. The solid-phase mass fraction of Al2O3 ceramic slurry and the porosity of the green body reached 52% and 83%, respectively. According to the TG-DSC curve and two-way analysis of variance, the optimum technological parameters for debinding and sintering of Al2O3 ceramic green body were determined. The same shrinkage of Al2O3 ceramic prepared by pressureless sintering in all directions was confirmed. The density of sintered lattice structure Al2O3 ceramic was 95%, and the diameter of the lattice structure strut was about 170 μm. XRD and Raman spectrum showed that the crystal phase of the sintered Al2O3 ceramic was α-phase, which has a good crystal quality. SEM results revealed a high density without significant pores and cracks sintered ceramic. The strict complex structure Al2O3 ceramic prepared by DLP technology had a compact microstructure and similar to the mechanical strength of Al2O3 prepared via the conventional shaping method, thereby providing an effective method for fabricating large specific surface area ceramic radiators and fine ceramic components in other fields.
TL;DR: In this article, the authors developed a multifunctional hydrogel sensor based on a polyvinyl alcohol substrate with poly(3,4-ethylenedioxythiophene) as the conductive filler and a glycerin/water component solvent as the dispersion medium.
Abstract: Conductive hydrogel has shown significant promise in the field of wearable devices. However, the mediocre antifreezing property and relatively low strain sensitivity limit the application of these gels. Herein, we developed a multifunctional hydrogel sensor based on a polyvinyl alcohol substrate with poly(3,4-ethylenedioxythiophene) as the conductive filler and a glycerin/water component solvent as the dispersion medium. The resulting optimal sample exhibits attractive combination of high tensile stress (~ 1.0 MPa), large elongation (> 400%), reasonable conductivity (~ 3.5 S m−1), while the glycerin/water solvent enable the hydrogel with a great antifreezing and moisturizing property. Accordingly, it was envisioned that the valid design method for conductive hydrogels with antifreeze, toughness, and moisturizing properties would provide wide utilizations of flexible wearable strain sensor.
TL;DR: In this article, a review discuses the extraction of cenosphere from coal fly ash, its characterization (physical and chemical) and applications in different industries, as well as its condescending properties such as high workability, thermal resistance, compressive strength and low conductivity.
Abstract: In thermal power plants, pulverized coal combusts to give an intricate composition of anthropogenic materials such as fly ash (coal). These materials are a major threat to environmental (air and water, etc.) pollution if dispose of to landfill sites and rivers. Since the last two decades, research and efforts are going on to reduce production and derivation of potentially valuable materials from coal fly ash such as cenosphere. Cenosphere is a low density, chemically inert and spherical material filled with air/inert gas (either nitrogen or carbon dioxide). Cenosphere is considered to be the most important fraction of fly ash as it is being used in different industries due to its condescending properties such as high workability, thermal resistance, compressive strength and low conductivity, bulk density. This review discuses the extraction of cenosphere from fly ash, its characterization (physical and chemical) and applications in different industries.
TL;DR: In this paper, the authors review and analyze the relevant literature and summarize the material preparation, optimization of process parameters, resultant improvements, and corresponding strengthening mechanisms for each major category of metal matrix composites.
Abstract: Metal matrix composites (MMCs) generally possess superior properties than the monotonic matrix alloys, and thus, they have become excellent candidate materials in various applications. Also, the ability of property tailoring at an affordable cost is of particular importance to industries. Among the many manufacturing techniques for MMCs, laser-assisted additive manufacturing (AM) techniques have emerged and drawn increasing attention in the past decade. In the literature, a wealth of studies have been carried out on the synthesis of MMCs via laser-assisted AM techniques, as well as the property evaluation of the obtained MMCs. In this paper, we review and analyze the relevant literature and summarize the material preparation, optimization of process parameters, resultant improvements, and corresponding strengthening mechanisms for each major category of MMCs. Moreover, the limitations and challenges related to MMC synthesis using the laser-assisted AM techniques are discussed, and the future research directions are suggested to address those issues.
TL;DR: In this article, the critical factors and mechanisms of HA coating using the electrochemical deposition method are comprehensively evaluated, thereby examining the effects of parameter optimization (i.e., current mode, ultrasonic treatment, and postprocessing).
Abstract: Bio-ceramic hydroxyapatite (HA) coating has been commonly used to repair the bones or as the functionalized surface of bone substitutes due to its excellent biocompatibility, superior osteo-inductivity, and great corrosion resistance. Among many other methods for synthesizing HA coating, coating via the electrochemical deposition has a high degree of crystallinity and purity, which fits the nonlinear, complex, and rugged substrates. Furthermore, HA coating can be adjusted in terms of coating morphology, thickness, and chemical component via changing the parameters, such as electrolyte ion concentration, electrolyte composition, deposition current density, and deposition time, etc. Nevertheless, the properties of electrodeposited HA coating highly pertain to the bubbles generated by water electrolysis on the substrate surface as well as the concentration polarization of electrolyte ions near the cathode during the electrodeposition process. In this study, the critical factors and mechanisms of HA coating using the electrochemical deposition method are comprehensively evaluated, thereby examining the effects of parameter optimization (i.e., current mode, ultrasonic treatment, and postprocessing). Finally, the influences of ion substitution and HA composite coating on the surface structure and properties of the HA-based coatings are also discussed.
TL;DR: In this paper, the authors developed a facile yet scalable fabrication of nitrogen doping porous carbon (QPC-3) with high specific surface area (SSA) of 2597m2 g−1 derived from quinoa.
Abstract: Biomass-derived porous carbon materials have been receiving considerable attention in energy-storage devices by virtue of the abundant and renewable sources. In this work, we developed a facile, yet scalable fabrication of nitrogen doping porous carbon (QPC-3) with high specific surface area (SSA) of 2597 m2 g−1 derived from quinoa. The QPC-3 electrode exhibits a special capacitance of 330 F g−1 in 6 M KOH at a density of 1 A g−1 and a good rate capability. Additionally, symmetrical supercapacitors assembled by QPC-3 can deliver capacitances of 254 F g−1 and 99.2 F g−1 at 0.5 A g−1, and the energy densities approach 9.5 Wh kg−1 and 22 Wh kg−1 in aqueous and organic electrolyte, respectively. The results suggest that this quinoa-derived porous carbon could be a promising biomass-derived electrode material applied in high-capacitance supercapacitors.
TL;DR: In this paper, a flexible and conductive Ti3C2Tx MXene/carbon nanotubes (CNTs) composite film was prepared through a simple vacuum filtration of the 2D transition metal carbides or nitrides with high electrical conductivity.
Abstract: MXenes are 2D transition metal carbides or nitrides with high electrical conductivity that have attracted great attention as promising electrode materials that supersede carbon-based material designed for supercapacitors. However, the aggregation and self-restacking of MXene 2D nanosheets limit their high-rate performance. In this work, flexible and conductive Ti3C2Tx MXene/carbon nanotubes (CNTs) composite film was prepared through a simple vacuum filtration of the Ti3C2Tx MXene and CNTs suspension mixture. The CNTs integrated MXene nanosheets can effectively prevent the restacking while creating fast ion transport channels for enhanced capacitance. The designed films exhibit excellent performance as supercapacitor electrodes with high capacitance of 300 F g−1 at 1 A g−1 with superior rate performance of 199 F g−1 even at 500 A g−1, together with excellent cyclic stability of 92% capacitance retention after 10000 cycles at 20 A g−1. The excellent workability demonstrates potential application of the system for flexible, portable and highly integrated supercapacitors.
TL;DR: In this paper, Mo-doped CuO nanosheets on Ni foams were obtained by combining a simple hydrothermal process and calcination treatment, which exhibited the best electrical conductivity and the highest specific capacitance at 2 A g−1.
Abstract: Copper oxide (CuO) electrodes have outstanding potentials for supercapacitors in virtue of their low cost, environment friendly, especially, and the high theoretical specific capacitance (1800 F g−1). However, their poor electronic conductivity restricts the practical application. Doping appropriate transitional metal ions into host materials is an effective method to modulate the electronic structure and improve the conductivity, furthermore, enhancing the energy storage capacity. Herein, Mo-doped CuO nanosheets on Ni foams were obtained by combining a simple hydrothermal process and calcination treatment. Different doping concentrations of Mo were discussed, and the as-prepared 3 at.% Mo-doped CuO (Mo-CuO-2) exhibited the best electrical conductivity and the highest specific capacitance of 1392 F g−1 at 2 A g−1. In addition, an asymmetric supercapacitor device was assembled using Mo-CuO-2 and activated carbon as a positive electrode and a negative electrode, which exhibited a remarkable energy density of 36 Wh kg−1 at 810 W kg−1 and an excellent cycle life with 81% capacitance retention for over 5000 cycles. More significantly, Mo-CuO-2 is a promising material candidate for practical energy storage applications.