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ABSTACT In this study, we suggest a simple and effective one-pot hybrid reduction process for the mass production of high-quality reduced graphene oxide (rGO) by simultaneously doing deoxygenation and healing reactions. During the microwave-irradiated thermal reduction, intercalated benzene in the GO easily generates acetylene by pyrolysis; the released acetylene react with surrounding defect sites in the GO surface to successfully form new C–C bonds. As a result of the newly formed sp2-hybridized C–C bond in the rGO surface, the defect-repaired rGO (rGO-B) shows remarkably enhanced crystallinity (ID/IG ratio: rGO-B, 0.63; rGO-T, 1.08), thermal stability, and electrical properties over that of rGO prepared without a carbon-source supplement (rGO-T). Especially, compared to the rGO-T, the rGO-B had 4.4 times more carrier density and 18 times increased carrier mobility because of the restoration of defect sites in the rGO-B surface. The rGO-B exhibited six times higher electrical conductivity than did rGO-T because of the improved carrier mobility. These results obviously suggest that the reduction of GO by means of microwave-irradiated thermal reduction with a carbon-source supplement could be a powerful approach for commercial mass production of high-quality rGO because of its easy manufacturing approach.

Recently, polymer nanocomposites have become among the most effective approaches to creating multifunctional materials with significant improvement in their electrical, physical, and chemical properties. This nanocomposite material has been widely studied in both academia and industry due to its outstanding properties for various energy-related applications. Polymer nanocomposites based on silica, carbon nanotubes, graphene, boron nitride, and metal oxides are chosen for energy-related applications. Various synthesis methods to achieve polymer nanocomposites have been discussed. In addition, the surface morphological characteristics have been highlighted to realize the structure-property relationship. Finally, this chapter describes recent promising research on polymer nanocomposites for applications in supercapacitors, solar cells, lithium-ion batteries, lithium-sulfur batteries, lithium-air batteries, and fuel cells in detail, including the future scope of the study.

Highly flexible quasi solid-state batteries are promising in next-generation energy storage sectors due to their high energy density, power density, and low manufacturing cost. However, poor cycle life seriously limits their application in industrial sectors. Herein, a novel strategy is established to design the oxygenated cobalt vanadium selenide (O-Cox V1-x Se2 ) nanostructures for high-performance quasi solid-state (QSS) zinc-cobalt batteries (ZCBs) and zinc-air batteries (ZABs). Density functional theory (DFT) calculation reveals that the doping effect of Co2+ into O-VSe2 nanostructure could increase the density of states near the edge of the conduction band, demonstrating ultrafast electron transport kinetics. Most interestingly, the optimal O-Co0.33 V0.67 Se2 cathode-based QSS-ZCB exhibits an ultrahigh specific capacity of 422.7 mAh g-1 at a current density of 1 A g-1 , excellent energy density of 186.4 Wh kg-1 , tremendous power density of 5.65 kW kg-1 , and ultralong cycle life (86.9% capacity retention after 3000 cycles). Furthermore, O-Co0.33 V0.67 Se2 air-cathode based QSS-ZAB delivers a peak power density of 162 mW cm-2 and ultralong cycle life over 100 h. These experimental and theoretical studies indicate that the electrochemically induced, cobalt stabilizes the vanadium is essential to boost the energy storage properties and cycle life of both ZCBs and ZABs.

To develop a flexible display, smartphones with edge screens with curved displays on both sides of the main screen have been used widely. Considering that small differences in the form of smartphones, such as length, width, and thickness, could affect user experience, the effects of the curvature of the edge screen should be identified. This study aimed to investigate the effects of the curvature of edge screens on subjective feelings of smartphone users and to find out the optimal curvature. In the experiment, four nonfunctional samples with different radii of curvature (4R/6R/8R/10R) were used as samples, and participants evaluated the five subjective feelings: grip/control comfort, front/side visibility, and stability of the samples with four usage patterns. Our results revealed that 8R is the optimal curvature for the edge screen based on subjective feelings in smartphone usage. Moreover, the effect of the curvature of the edge screen on grip comfort and control comfort varied according to the usage patterns. The results of this study can be applied to design of the curvature of edge screens in smartphones and it is expected that it will contribute to improvement of users&rsquo, satisfaction.

In this work, hierarchical manganese-nickel sulfide nanosheet arrays (Mn-Ni-S NAs) were designed through a cost-effective hydrothermal method, followed by an ion-exchange technique. Among the various electrode samples prepared, Mn-Ni-S NAs with a Mn/Ni feeding ratio of 1:2 (denoted Mn-Ni-S NAs (1:2)) were found to possess outstanding electrochemical properties, including a superb areal capacity of 0.687 mAh cm

Fabrication of hierarchical nanosheet arrays of 1T phase of transition-metal dichalcogenides is indeed a critical task, but it holds immense potential for energy storage. A single-step strategy is employed for the fabrication of stable 1T-Mn

The development of a bifunctional hierarchical nanostructure catalyst with high activity, low cost, excellent reversibility, and binder-free is an emerging key demand in industrial application for overall water splitting. In this work, a new strategy was employed for the rational design of 3D hierarchical oxygenated nickel tungsten selenide on conductive nickel foam substrate (O–Ni1−xWxSe2/NF) by a low-cost hydrothermal process, followed by a partial controlled-selenization process. Owing to the enriched oxygenated intermediates and abundant active sites with nanoporous networks, the optimal O–Ni0.5W0.5Se2 hierarchical nanostructure shows excellent catalytic activities for hydrogen evolution and oxygen evolution reactions, which exhibit a low overpotential of ∼ 109 and 238 mV at 20 mA cm−2, with remarkable durability. Most significantly, the O-Ni0.5W0.5Se2||O-Ni0.5W0.5Se2 electrolyzer required a small cell voltage of ∼ 1.56 V at 10 mA cm−2. The present study suggests a new strategy for designing highly active hierarchical 3D oxygenated enriched metal selenide as a durable bifunctional electrocatalyst.

Metallic (1T) transition metal dichalcogenides (TMDCs) shows great potential for electrocatalytical water−splitting (ECWS). Among different 1T−TMDCs, vanadium (V)−based 1T−TMDCs has highest thermodynamic stability. Now, among different V−based 1T−TMDCs, 1T−VTe2 holds the best potential for ECWS due to strongest interlayer coupling between V and Te. In the present study, we have developed nickel nanoclusters (NiNCs) hybridized and manganese (Mn) intercalated and doped 1T−VTe2 nanosheets (NiNCs-1T-Mn-VTe2 NS) for ultra−low potential ECWS. Mn doping and intercalation in 1T−VTe2 (1T−Mn−VTe2) significantly improve ECWS efficacy following improving oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) performances. Hybridization of NiNCs with1T−Mn−VTe2 develop a true ECWS−catalyst NiNCs-1T-Mn-VTe2 NS for ultra−low potential water−splitting. NiNCs−1T−Mn−VTe2 NS showed excellent performance requiring only HER−overpotential of 61 mV to reach 10 mA cm−2 and OER overpotential of 258 mV to reach 40 mA cm−2. NiNCs−1T−Mn−VTe2NS (+ −) device required a cell potential of 1.51 V to reach 10 mA cm−2.

A series of proton-functionalized graphitic carbon nitride (fgC3N4) modified reduced graphene oxide (rGO)/nickel-aluminium layered double hydroxide (LDH) composites (fgC3N4-rGO/LDH-1 and fgC3N4-rGO/LDH-2) were prepared by a novel scalable strategy using different amounts of fgC3N4-rGO as a conductive matrix. The morphological analyses reveal that the LDH sheets are gradually assembled on the fgC3N4-rGO matrix. The fgC3N4-rGO and LDH mutually minimize their self-aggregation in fgC3N4-rGO/LDH composite. The porous skeleton of fgC3N4-rGO/LDH-1 (highest loading of fgC3N4-rGO matrix) produces a high surface area (240 m2/g) and mesopores (diameter; 2.2 nm). The fgC3N4-rGO/LDH-1 electrode generates a specific capacitance value of 1190 F g−1 at 1 A g−1, excellent rate performance (71% at 10 A g−1), and good cycling stability (90% after 3000 cycles), in a three-electrode setup. Hierarchical fgC3N4 functionalized rGO composite (3D-fgC3N4@rGO) was used as a negative material. The 3D-fgC3N4@rGO produces an excellent capacitance of 345 F g−1 at 1 A g−1, high rate capability (74% at 10 A g−1) and good cyclic stability (90% after 3000 cycles). The fgC3N4-rGO/LDH-1 and 3D-fgC3N4@rGO were assembled to fabricate a solid-state asymmetric supercapacitor device using KOH/PVA gel electrolyte. The device operates within the potential window of 1.6 V and produces the highest energy density and power density of 54.76 W h kg−1 and 12031.92 W kg−1, respectively. The solid-state device shows an excellent cycle life of 91% after 7000 cycles, and it can power a red LED, suggesting very efficient for practical application.

Polyelectrolyte-decorated graphene with positive and negative charges was prepared using graphene oxide as a precursor along with polyallylamine hydrochloride and poly (styrenesulfonate sodium) as surface modifiers, respectively. Driven by an electrostatic interaction, the as-obtained polyelectrolyte-decorated graphene sheets were self-assembled via a layer-by-layer method, producing graphene based composite multilayers. Field emission scanning electron microscopy (FE-SEM) images showed that the surface of composite film exhibited a mass of characteristic wrinkles of graphene. Interestingly, the cross-sectional FE-SEM of the film exhibited an unstratified structure, indicating a good dispersion of graphene sheets in the composite film. The results of oxygen gas permeability testing demonstrated that the resulting composite films exhibited excellent oxygen gas barrier properties. The oxygen gas transmission rate (OTR) of the composite film with 24 bilayers was as low as 1.2 cm3 m-2 d-1∙atm−1, exhibiting potential for use in packaging applications.

Solid-state supercapacitors (SCs) are well-known as one of the most competitive power sources for modern electronics. However, most of the reported solid-state SCs suffer from low specific capacitance and energy density. Herein, a novel strategy for the synthesis of nickel vanadium oxide (Ni3V2O8) and iron vanadium oxide (Fe2VO4) nanoparticles (NPs) anchored nitrogen doped graphene (NG) for high energy solid-state asymmetric SC (ACS) through a simple and cost-effective hydrothermal technique was demonstrated. SEM and TEM analysis reveals that active Ni3V2O8 and Fe2VO4 NPs with uniform size are anchored on NG sheets. Electrochemical performance of Ni3V2O8/NG and Fe2VO4/NG electrodes showed that both have ultra-high specific capacitances (∼1898 F g−1 and 590 F g−1 at current density of 1 A g−1, respectively), tremendous rate capabilities, and superior cycling stabilities. Most significantly, solid-state ASC consisting of Ni3V2O8/NG as a cathode and Fe2VO4/NG as an anode which achieves a high energy density of ∼77.2 W h kg−1 at a power density of 863 W kg−1 and an ultra-long cycle life (capacitance retention of ∼83.3% after 20,000 cycles). This study emphasizes the development of a wide variety of energy storage systems for modern electronics.

Recently, three-dimensional (3D) architectures of graphene-carbon nanotubes (CNTs) have attracted a lot of attention due to their multifunctional properties. In this study, we have reported a novel 3D graphene-CNTs/MoO3 hybrid film as a binder free electrode material with unique morphology and outstanding electrochemical performance. The optimized 3D graphene-carbon nanotubes (GF-CNTs) framework was fabricated by a chemical vapor deposition (CVD) process on Ni foam skeleton. Further, controlled loading of MoO3 nanoplates were grown on the GF-CNTs framework as a hybrid film, using an easy and low cost hydrothermal method. The as-fabricated hybrid electrode exhibits remarkable specific capacitance of 1503 F g−1 at 1 A g−1 and 798.93 F g−1 at a current density of 10 A g−1, as well as exceptional capacitance retention of 96.5% after 10,000 cycles. The excellent electrochemical performance of the electrode material can be attributed to the combination of pseudocapacitance and electric double layer capacitance contributed by the MoO3 nanoplates and graphene foam/CNTs in the hybrid system, respectively. The asymmetric supercapacitor (ASCs), assembled from GF-CNTs/MoO3 and GF-CNTs as positive and negative electrode, respectively, delivers excellent specific capacitance of 211.71 F g−1 at current density of 1 A g−1. The ASCs device also exhibits a maximum energy density of 75.27 W h kg−1 at a power density of 816.67 W kg−1 with excellent cycling ability of 94.2% of the initial capacitance after 10,000 cycles. These results suggest that the as-fabricated GF-CNTs/MoO3 hybrid architecture can be used as a promising electrode material for the next generation supercacitor devices.

Demand for an effective strategy for exfoliating layered materials into flakes without perturbing their intrinsic structure is growing. Herein, we introduce an effective fabrication method of large-sized non-oxidized graphene flakes (NOGFs) as a representative example of a general strategy using spontaneous insertion of exfoliating medium into a layered material. We fabricated a ternary graphite intercalation compound (t-GIC) with stoichiometry of KC24(THF)2, and analyzed its morphology and electronic structure through experimental and computational approach. Interactions between the t-GIC and aprotic organic solvents with different polarities were investigated, where a unique swelling behavior was observed with dimethyl sulfoxide (DMSO). Based on the analysis of the phenomena, we demonstrate facile exfoliation of the t-GIC in polyvinyl pyrrolidone (PVP)-DMSO solution for fabrication of highly crystalline and large-sized NOGFs. The lateral size of the NOGFs ranges over 30 μm, while the 98% having thickness below 10 layers. The NOGF film exhibits supreme electrical conductivity of 3.36 × 105 S/m, which is, to our best knowledge, the highest value for a thin conductive film made of graphene flakes.

This study analyzed the anthropometric mismatch between the height systems of the primary school furniture and children in Korea. The results revealed that the height systems of present desks matched the height of only half of the children. The cause of this was a drawer attached underneath the desk board. In case of the height system of present chairs, almost all children matched; however, some levels were of no use to the students. To increase the degree of matching, new height systems were developed for the desks and chairs via an algorithmic approach. It was confirmed that the new height system for desks could significantly increase the degree of matching, whereas the new height system for chairs comprised five levels that could be matched to all children. The proposed algorithmic approach is expected to be applied to the development of size systems for other products.

A three-dimensional hierarchical nanohybrid based on Cu-Au bimetallic nanocrystals integrated carbon nanotube arrays vertically grown on carbon spheres was successfully developed as an active platform for sensing application. Such nanohybrid can provide abundant active sites and act as an exceptional platform for immobilizing highly dense and well-dispersed carcinoembryonic antibody (anti-CEA) to sensitively detect CEA, an emerging biomarker of various cancer diseases. Due to the unique nanoarchitecture with altered electronic structure of Cu-Au bimetallic catalyst and enhanced interactions between components, such nanohybrid based biosensor demonstrated excellent electrochemical performance towards CEA detection with great sensitivity, wide linear detection range (0.025–25 ng/mL), very low limit of detection (0.5 pg/mL), and good selectivity. The results imply that this sensor has great potential to offer essential information for cancer diagnosis and management with great clinical importance.

Development of highly functional and durable catalysts in a cost-effective way is a promising approach for practical energy conversion applications. In this study, a novel catalyst, cobalt iron carbide nanoparticles encapsulated by nitrogen doped graphene nanosheets, is successfully synthesized through a simple refluxing strategy followed by a post annealing process. It is found that the catalyst exhibits excellent catalytic activity for oxygen reduction reaction in alkaline medium. The oxygen reduction reaction kinetics of the catalyst mainly follow a 4-electron transferred pathway along with good diffusion limit current density, highly positive onset potential (−0.04 V) and half-wave potential (−0.11 V). In addition to catalytic activity, the catalyst demonstrates advanced superior stability, and excellent methanol tolerance in comparison with commercial platinum catalyst. The impressive catalytic performance of the catalyst is attributed to the unique mesoporous metal-core/graphene-shell architecture in which high interactions between two transition metals and transition metal-carbon synergistically provide enhanced catalytically active sites, accelerate interfacial charge transfer, and optimize oxygen adsorption energy. The results demonstrate that such catalyst can be an alternative low-cost and efficient catalyst for oxygen reduction reaction in energy conversion applications.

Development of cost-effective, rich-reserve, and highly efficient substitutes to replace the precious metal catalysts is necessary in the field of electro-catalysis to reduce the costs and enhance the efficiency of catalysts. Although, various nonprecious metal catalysts have received much attention, some critical issues still remain in practically applied catalytic processes due to their insufficient activity and poor stability. A novel and potential approach to design catalysts based on nonprecious metal encapsulated by two-dimensional (2D) carbon supporting materials has demonstrated unique advantages in terms of enhanced catalytic activity and stability, especially under harsh operational conditions. This is due to the enriched electrochemical active sites and highly improved interaction between the components by exceptional structural design and alternation of the associated electronic properties. This review highlights the recent advancement of state-of-the-art research on the synthesis, morphology, properties, and applications of the transition metal-based catalysts encapsulated in 2D-carbon supporting material hybrids. The pros and cons of various synthesis methods are discussed in detail to understand the relationships between such unique morphology/structure and physicochemical properties for enhanced catalytic performance. In addition, their potential electrochemical applications are also emphasized, including biosensors, supercapacitors, batteries, fuel cells, and water splitting. Finally, the current challenges in fundamental research and practical applications, and forthcoming opportunities for these promising materials, are also briefly discussed.

To explore a natural nonenzymatic electrode catalyst for highly sensitive and selective molecular detection for targeting biomolecules is a very challenging task. Metal nitrides have attracted huge interest as promising electrodes for glucose and hydrogen peroxide (H2O2) sensing applications due to their exceptional redox properties, superior electrical conductivity, and superb mechanical strength. However, the deprived electrochemical stability extremely limits the commercialization opportunities. Herein, novel nitrogen-doped graphene-encapsulated nickel cobalt nitride (NixCo3–xN/NG) core–shell nanostructures with a controllable molar ratio of Ni/Co are successfully fabricated and employed as highly sensitive and selective electrodes for glucose and H2O2 sensing applications. The highly sensitive and selective properties of the optimized core–shell NiCo2N/NG electrode are because of the high synergistic effect of the NiCo2N core and the NG shell, as evidenced by a superior glucose sensing performance wit...

A unique and novel structural morphology with high specific surface area, highly synergistic, remarkable porous conductive networks with outstanding catalytic performance, and durability of oxygen reduction electrocatalyst are typical promising properties in fuel cell application; however, exploring and interpreting this fundamental topic is still a challenging task in the whole world. Herein, we have demonstrated a simple and inexpensive synthesis strategy to design three-dimensional (3D) iron tungsten oxide nanoflower-anchored nitrogen-doped graphene (3D Fe-WO3 NF/NG) hybrid for a highly efficient synergistic catalyst for oxygen reduction reaction (ORR). The construction of flowerlike Fe-WO3 nanostructures, based on synthesis parameters, and their ORR performances are systematically investigated. Although pristine 3D Fe-WO3 NF or reduced graphene oxides show poor catalytic performance and even their hybrid shows unsatisfactory results, impressively, the excellent ORR activity and its outstanding durabil...

In this work, the hybridization effects of hydrazine reduced graphene oxide (rGO) on the inter-laminar shear strength (ILSS), impact strength, and in-plane fracture toughness of symmetric type carbon fiber/epoxy composite (CF/epoxy) laminates were investigated. The composite laminates were fabricated through the vacuum-assisted resin transfer molding (VARTM) process. At 0.2 wt% of rGO loading, the CF/epoxy composites showed the best load carrying capacity among the developed laminates. ILSS, impact strength, and critical stress intensity factor (KIC) were enhanced by ∼ (84, 100, and 33) %, respectively, in the case of rGO (0.2 wt%) filled CF/epoxy composite specimens, as compared to CF/epoxy composite. The consumed fracture energy of rGO (0.2 wt%)/CF/epoxy increased, as compared to the rGO (0.4 wt%)/CF/epoxy composite. The fracture surfaces obtained from field emission scanning electron microscopy of the developed composites showed compatible dispersion of rGO in the epoxy matrix, and branched fracture of the specimens. This study suggests that the rGO nanofiller might be used as a matrix modifier to resist matrix fracture, as well as fiber fracture.

Graphene oxide (GO-E) with high electrical conductivity was eco-friendly synthesized through a hydroxylation reaction in water. The graphite was oxidized via hydroxylation of the alkene groups in a deionized (DI) water to obtain graphite oxide (O-Gr). The O-Gr was mechanically exfoliated into GO-E by applying shear force with a homogenizer in a polar solvent. The GO-E was highly dispersible in a polar solvent in single- or few-layered GO-E sheets with an average area of 580 μm2. The Raman intensity ratio of the G-band to D-band (ID/IG) demonstrates that the hydroxylation reaction can produce GO-E with less defects compared to the Hummer's method (GO-H). Furthermore, the GO-E exhibited a high electrical conductivity of 760 S/m, which was much higher than that of GO-H. The GO-E and GO-H filled Polyimide (PI) composites were prepared by the in-situ polymerization and the GO-E/PI composite showed higher electrical conductivity than that of GO-H/PI composite. Thus, this approach provides us a simple, efficient and eco-friendly synthesis way of GO with high electrical conductivity for composite applications.

Poly(diallyldimethylammoium chloride) (PDDA)/acid or base modified graphene oxide (MGO) composite (PDDA/MGO)-based gas barrier films were prepared by layer-by-layer (LBL) assembly method on polyeth...

The development of new advanced nanostructures based on the hybridization of different carbon nanomaterials to obtain enhanced performance of energy storage devices has attracted considerable attention. Herein, a hierarchical nanostructure of carbon nanotubes supported electrospun carbon nanofiber networks (CNTs@CNFs) was successfully fabricated by using two facile techniques: – electrospinning and chemical vapor deposition (CVD). Such CNTs@CNFs hybrid showed the uniform and high density of CNTs directly grown on the surface of carbon nanofiber networks, leading to the formation of a hierarchical nanostructure with a large surface area and highly porous characteristics. The enhanced interactions between the CNTs and the CNFs networks were found to improve the electrical conductivity and electrochemical stability of the material. Owing to its unique nanoarchitectures and physicochemical properties, the CNTs@CNFs hybrid was demonstrated to be a potential electrode material for an electrochemical capacitor, in which a high specific capacitance of 464.2 F g−1 at 0.5 A g−1 and long-term stability with 97% retention after 10,000 repeated charge–discharge cycles were achieved. The obtained results suggest that the present CNTs@CNFs hybrid is a promising candidate for an electrochemical capacitor in energy storage technologies.

In this study, a facile approach has been successfully applied to synthesize a hierarchical three-dimensional architecture of ultrasmall hematite nanoparticles homogeneously encapsulated in MoS2/nitrogen-doped graphene nanosheets, as a novel non-Pt cathodic catalyst for oxygen reduction reaction in fuel cell applications. The intrinsic topological characteristics along with unique physicochemical properties allowed this catalyst to facilitate oxygen adsorption and sped up the reduction kinetics through fast heterogeneous decomposition of oxygen to final products. As a result, the catalyst exhibited outstanding catalytic performance with a high electron-transfer number of 3.91–3.96, which was comparable to that of the Pt/C product. Furthermore, its working stability with a retention of 96.1% after 30 000 s and excellent alcohol tolerance were found to be significantly better than those for the Pt/C product. This hybrid can be considered as a highly potential non-Pt catalyst for practical oxygen reduction r...

Herein, we synthesized few-layered water dispersible two dimensional (2D) MoS2 nanosheets using thiourea by a facile hydrothermal method. The MoS2 nanosheets consisted of graphene-like structures that are 4 nm in thickness and ∼2 μM in size as observed from AFM analysis. The incorporation of MoS2 nanosheets into the poly(vinyl alcohol) (PVA) matrix significantly improved the thermal and dielectric properties of the fabricated nanocomposites (PVA-MoS2). The nanocomposite films demonstrated tremendous enhancements of the tensile strength (56%), modulus (42%), and toughness (more than 300%) after incorporation of 2 wt% of MoS2 nanosheets. The nanocomposite films also exhibited outstanding barrier towards hydrogen; specifically, the nanocomposite with 2 wt% of MoS2 nanosheets exhibited a decrease of almost 94% in its permeability than the PVA film for hydrogen gas. Different theoretical models have been applied to investigate the nature of dispersion of MoS2 inside the PVA matrix based on tensile modulus and permeability.

In this study, carbon nanotube (CNT) hybrid aerogels with high mechanical properties were fabricated by interconnecting structural networks of CNTs using poly(vinyl alcohol) (PVA) through amine-functionalized iron oxide (NH2-Fe). Consequently, Fe-CNT-PVA hybrid aerogels exhibited good structural stabilities, even under repeated loads due to the interconnection bonding with PVA between neighboring CNTs. Furthermore, compared to the Fe-CNT aerogels, the Fe-CNT-PVA hybrid aerogels showed ∼3 times higher specific surfaces due to the tuning of the internal morphology by controlling electromagnetic interactions between NH2-Fe on the surface of the CNTs and the applied magnetic field. These results clearly show that CNT aerogels with both improved structural stabilities and specific surface areas can be fabricated by the method proposed in this study.

A new series of boric acid (BA) induced cross-linked poly(vinyl alcohol-co-ethylene) (EVOH)/graphene oxide (GO) nanocomposite (EVOH/BA/GO) films are prepared using different amount of GO and BA with respect to EVOH. The EVOH/BA/GO nanocomposites are respectively coated on nylon films and stainless steel substrates by a typical spray coating method, followed by thermal and hydrazine vapor treatment for gas barrier and corrosion studies. The Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses confirm the formation of cross-linked nanocomposite through the formation of B–O–C bond. The field emission scanning electron microscopy analysis indicates the formation of homogeneous structure for these nanocomposites. The storage modulus (at 25 °C) and elastic modulus of EVOH/15BA/5GO-coated film with 15% BA and 5% GO are enhanced by 280 and 60%, respectively, in comparison to nylon film. EVOH/15BA/5GO-coated nylon film exhibits dramatic reduction of hydrogen (6.9) and oxygen gas (1.5) transmission rates (cc/m2∙d∙atm) than pure nylon film. In addition, EVOH/15BA/5GO-coated stainless steel shows an ultralow corrosion current (0.294 μA/cm2) and corrosion rate (3.43 × 10−3 mm/year) than steel. A comparative study between EVOH/BA/GO and EVOH/GO is performed to examine the effect of the cross-linker on the different physical properties.

Synthesis of palladium (Pd) nanostructures with unique shapes is crucial due to their shape dependent electrochemical activity. In the current investigation, we demonstrate the electrochemical synthesis of rod-like Pd nanostructures with the assistance of nicotinamide adenine dinucleotide (NAD+). As-synthesized Pd nanorods were used as electrocatalysts for electrochemical oxidation of methanol and the development of highly sensitive platform for hydrazine detection. Additive NAD+ played an important role in the morphology tuning of Pd nanostructures. Results of morphological study demonstrated the growth of Pd nanorods with an average size of 150 nm. The as-synthesized Pd nanorods had excellent electrocatalytic activity toward oxidation of methanol in alkaline pH and hydrazine oxidation in neutral pH. These Pd nanorods catalyzed the electrooxidation of methanol at −0.17 V with much better tolerance, excellent stability, and oxidation of hydrazine at −0.075 V. The Pd nanorod-based sensing platform delivered a low detection limit of 5 nM, sensitivity of 0.78 ± 0.02 μA mM−1cm−2, and stable response toward hydrazine sensing without any interference from potential interferents such as Na+, K+, NO2−, BrO3−, or Pb2+ ion. Their electrochemical performances were found to be highly dependent on the morphology of Pd nanostructures.

Recently, the research effort on two-dimensional transition metal dichalcogenides/graphene (2D-TMDs/Gr) hybrids has grown. These hybrids are emerging as a promising strategy for the preparation of advanced multifunctional materials with effectively upgraded properties, as well as performances. Due to their outstanding electrical, physical, and chemical properties, these materials have been extensively considered for various applications, both in academia, and industry. This review systematically assesses the important progress to date in the development of 2D-TMDs/Gr hybrids. The synthesis methods of 2D-TMDs/Gr hybrids for fabricating diverse types of nanostructured architectures are highlighted. In addition, the relationships between morphological and structural characteristics, and the physicochemical properties of 2D-TMDs/Gr hybrids, are recognized in detail. This review also discusses recent prospective applications of the 2D-TMDs/Gr hybrids in the areas of energy storage, energy conversion, energy harvesting technologies, and sensors. In summary, although there are still challenges for optimizing the synthesis process and performance of the 2D-TMDs/Gr hybrids, they offer unique candidates for a wide range of promising applications in the future.

In this study, a novel hierarchical porous network of Pt51Pd49 alloy-integrated graphene nanosheet as active catalyst towards ethanol oxidation was fabricated using electroless deposition followed by chemical vapour deposition for the first time. Such materials were obtained as a three-dimensional continuous and non-order porous architecture with good dispersion and uniformity of the ultrasmall Pt51Pd49 nanoalloy particles (∼3 nm) within the graphene nanosheets. As an electrocatalyst, it exhibited excellent catalytic behaviour towards ethanol oxidation with superior conversion, long-term stability and better tolerance towards intermediate's poisoning effect, as compared to commercial Pt black product. The results were associated with the enhanced electroactive surface area and mass transfer possibility of the catalyst due to the formation of an unique porous nanostructure for Pt51Pd49 alloys. In addition, the coating effect of graphene nanosheets over Pt51Pd49 alloy nanoparticles avoided aggregation and dissolution, possibly allowing full utilization of the active sites from all nanoparticles, and thus efficiently improving charge transfer ability and working stability of the catalyst. Owning high quality, good electrochemical performance, and ease of synthesis, the as-synthesized catalyst opens an interesting nanoarchitecture class for efficiently catalyzing ethanol oxidation in fuel cells.

Nacre-like graphene nanosheets (GNS) obtained from the l -glutathione mediated reduction of graphene oxide (GO) were used to develop epoxy composites. Field emission scanning electron microscopy (FE-SEM) revealed the layer-by-layer nacre-like structure of GNS. Fourier transform infrared spectra (FT-IR), X-ray diffraction (XRD), Raman spectroscopy, and thermogravimetric analysis (TGA) measurements confirmed the successful reduction of GO. The oxidized product of l -glutathione is expected to perform as capping agent to stabilize the GNS, and also stitches the graphene sheets through hydrogen bonding. Transmission electron microscopy was used to confirm the dispersion of GNS in the epoxy matrix. The GNS/epoxy composites showed significant improvement of ∼91% in fracture toughness (KIC), 46% in flexural strength, and 71% in flexural modulus at 0.25 wt% GNS loadings. The probable toughening mechanism was elucidated from fracture FE-SEM images. The improved compatibility and strong interfacial interaction were reflected in the enhanced storage modulus value. The thermal stability of the composites as investigated by TGA showed appreciable improvement in the degradation temperature.

To accomplish high-performance flexible energy storage devices, a new class of flexible electrodes with prosperous constructions bearing exceptional electrical conductivity, exclusive porosity, and outstanding mechanical stability is extremely needed. Here, we have successfully fabricated a highly flexible electrode with nanocomposite of polyaniline/manganese hexacyanoferrate PANI/MnHCF nanocomposite (PANI/MnHCF) on highly conductive carbon fiber (FCF). The nanocomposite exhibits an ultra-high specific capacitance of 730 F g−1 at a current density of 1 A g−1 with exceptional rate capability (350 F g−1 capacitance retention at a current density of 20 A g−1), and outstanding cycling performance (capacitance retention of ∼85% after 1000 cycles). The PANI/MnHCF/FCF electrode shows better electrochemical performance due to their exclusive properties such as excellent electrical conductivity, unique porous network and outstanding mechanical flexibility. Furthermore, the higher surface area of PANI/MnHCF nanocomposite facilitates the transport of electrons and electrolyte ions during rapid charge/discharge process. This present work offers a simple, scalable and cost-effective method for fabrication of other PANI/MnHCF nanocomposite based electrode, which is applicable for providing energy in practical flexible portable devices.

The jet effect in dry-jet wet spinning of a polyacrylonitrile (PAN) solution was investigated. The two parameters, jet-stretch ratio and air gap length, of the jet were controlled to elucidate each effect on PAN precursors and resulting carbon fibers. Excessively high jet-stretch ratio (>4) or air-gap (>1 cm) resulted in the development of the internal pore structure in PAN precursors. The pores remained even after the densification by thermal treatment acting as defects for poor tensile properties of carbon fibers (CFs). It was revealed that two parameters critically controlled the bidirectional diffusion of both solvent and non-solvent by determining the degree of the surface gelation at the jet. Excessively high jet-stretch ratio or high air-gap length created a thick solid skin on extruded dope limiting solvent/non-solvent diffusion. As a method to limit the development of the pores under the condition of high jet stretch ratio (>4), raising the dope temperature for limiting the degree of gelation at the jet was attempted and successfully manufactured mechanically improved fiber with a dense structure without pores under high jet-stretch condition. The study suggests that the high quality PAN precursors for high performance CFs can be manufactured under high jet-stretch ratio condition with proper management on gelation at the jet.

The purpose of this study is to examine the difference in the tactile perception between designers and customers for leathers in vehicle interiors and to derive preference models that describe the relationship between the tactile perception and physical measurements the leathers. An experiment was performed on ten natural leathers manufactured in the automotive industry. The questionnaires were designed based on six pairs of adjectives: wet-dry, slippery-sticky, smooth-rough, flat-bumpy, hard-soft, and thin-thick for sensory evaluation. In addition, eight physical measurements were selected to identify the characteristics of leathers that affect the tactile perception of designers and customers. The relationship between the experiment results and physical measurements was determined by correlation and regression analyses. The statistical results show a significant difference between designer and customer in the tactile properties of the leathers. Also, the tactile perception from both designers and customers was associated with more than one physical measurement, while the designers and customers showed different tactile association with physical measurements. This study contributes to the comprehension and recognition of the differences in preferences for leathers in vehicle interiors between designers and customers and, by designing the prediction model of preference based on the physical measurements, the uncertainty in the market for automobile manufacturers can be reduced.

Ternary nanocomposites (NCs) comprising Ag-Cu2O supported on glucose-reduced graphene oxide (rGO) with enhanced stability and visible light photocatalytic activity were synthesized via a facile and green approach using Benedict's solution and glucose solution at room temperature without the need of any toxic reagent, surfactant or any special treatment. Besides mild reducing capability to GO, glucose also induces the functionalization of rGO sheets, preventing the aggregation of reduced sheets and providing in situ stabilization to Cu2O. The resulting Ag-Cu2O/rGO NCs showed excellent photocatalytic efficiency for the photodegradation of methyl orange (MO), and the degradation rate was found to be higher than the pristine Cu2O and Cu2O/rGO NCs. Further, for the first time Ag-Cu2O/rGO NCs showed markedly enhanced photocatalytic efficiency for the photodegradation of phenol solution which is mainly attributed to its high electron injection rate and effective separation of electron–hole pairs. Thus, present strategy explores the facile synthesis way of varieties of Cu2O-based NCs materials using harmless reagents and their feasible applications.

Due to the increasing greenhouse gas emissions and gradual run out of fossil fuels, there is a growing concern on the environmental protections and global energy demands in the world. Therefore, new energy storage technologies have been continuously developed to be integrated with renewable energy systems in recent years. Nowadays, advanced composites are popular in automotive and aerospace industries because of their significant advantages such as high specific strength to weight ratio and non-corrosion properties. Therefore, research interests in developing multifunctional composite materials in order to reduce the fuel and energy consumption have increased significantly. Therefore, this paper is focused on the development of multifunctional energy storage systems. The introduction of structural dielectric capacitors and structural electric double layer capacitors (EDLC) are presented. Then, experimental findings, in terms of improvements on the mechanical and electrical properties of structural dielectric capacitors, and factors on the overall performance of structural EDLC conducted by other researchers are given. In addition, it has been proven that the structural dielectric capacitors could maintain their capacitive function under a mechanical loading. Lastly, challenges that would be faced in the realization of structural dielectric capacitors and structural EDLC are discussed.

The octadecylamine (ODA) modified graphene oxide (mGO-ODA)/maleic anhydride grafted polypropylene (MAPP) composites (mGO-ODA/MAPP) were prepared and applied successfully as gas barrier and corrosion protection coating materials for the first time. The hydrophobic mGO-ODA sheets showed improved solubility in non-polar solvents with molar absorptivity was found to be 36 mL mg−1 cm−1 in ethylcyclohexane. FTIR analysis confirmed that mGO-ODA chemically interacts with MAPP. The mGO-ODA nanosheets were well exfoliated and dispersed in the MAPP matrix as confirmed by XRD analysis. The mGO-ODA/MAPP composites were coated on modified nylon sheets by a spray coating method, and the gas transmission rates (GTRs) of H2 and O2 were tested for these coated films. Cross-sectional FESEM showed the excellent attachment of these composite with the nylon film. The 60% mGO-ODA/MAPP-coated nylon film exhibited 93% and 112% improvement in elastic modulus values than the MAPP-coated and pure nylon films, respectively. Besides, 60% mGO-ODA/MAPP exhibited 94.1% and 95.0% reduction for H2GTR and O2GTR, respectively, compared to the pure nylon film. In addition, mGO-ODA/MAPP coated steel substrate exhibited excellent anticorrosion performance. The corrosion inhibition efficiency and corrosion rate were calculated to be 99.15% and 2.26 × 10−3 mm/year, respectively, for 60% mGO-ODA/MAPP.

In this study, a novel 4,4′-diaminostilbene-2,2′-disulfonic acid (DASDSA)-functionalized reduced graphene oxide (DASDSA-rGO) was prepared via simple refluxing method involving GO and DASDSA in the presence of ammonia solution followed by reduction with hydrazine hydrate. FTIR spectroscopy, Raman scattering, X-ray photoelectron spectroscopy (XPS), and XRD analyses confirmed the successful functionalization and reduction of GO in DASDSA-rGO. The FTIR and XPS analyses also confirmed covalent bond formation between DASDSA and graphene. The DASDSA spacer successfully minimized the restacking of rGO sheets as observed from FESEM analysis. Several redox transition states and SO 3 H groups of grafted DASDSA moieties provided excellent pseudocapacitance performance of the DASDSA-rGO electrode. The DASDSA-rGO electrode showed high specific capacitance ( C ) value of 1042 F g −1 at a current density of 1 A g −1 , good cycling stability (95% capacitance retention after 3000 cycles), and excellent rate capability in a three-electrode setup. The DASDSA-rGO (positive electrode) and rGO (negative electrode) were assembled to prepare an asymmetric supercapacitor (ASC) device. The power density values of the ASC device were calculated to be 650 and 7800 W kg −1 at energy density values of 37.37 and 23.78 W h kg −1 , respectively. The ASC device exhibited C value of 159 F g −1 at 1 A g −1 and displayed 86% retention in C after 8500 cycles. The EIS data of the three-electrode system and ASC device were fitted with Z-views to determine the different resistance components after a different number of charge–discharge cycles in a cycling stability test.

CoFe2O4 nanospheres ornamented CdS nanorods were successfully assembled over the reduced graphene oxide nanosheets. Such hierarchical morphology established by field emission scanning electron microscopy and transmission electron microscopy studies, with high surface area offered a high specific capacitance of 1487 F g–1 at a current density of 5 A g–1 owing to fast diffusion of ions, facile transportation of electrons, and great synergism between the components, which led to reversible redox reactions. Furthermore, the electrode material has specific capacitance retention of 78% up to 5000 cycles, thus demonstrating its good reversibility and cyclic stability. The resulting CdS-CoFe2O4@reduced graphene oxide nanohybrid can deliver excellent electrochemical performance and can be a potential candidate for supercapacitor application.

Carbon black (CB)/ high-density polyethylene (HDPE)/polyaniline (PAni) functionalized multi-walled carbon nanotube (MWNT) hybrid nanocomposites were prepared by the combined solution and melt-mixing process. The influence of PAni-MWNTs on the positive temperature coefficient (PTC) characteristics of hybrid nanocomposites have been studied. The experimental results showed that the hybrid nanocomposites with small amount of PAni-MWNTs (0.50-0.75 wt%) have good conductivity at room temperature & PTC intensity was increased dramatically. The increase is possible because of the interaction between PAni and MWNTs which facilitates the charge transfer process. A noticeable PTC intensity was observed for hybrid nanocomposites near the melting point of HDPE. This is due to the significant volume expansion near the melting point of the HDPE in the presence of PAni-MWNTs and a sudden increase in the resistivity due to the disconnection of the conductive paths. Further PTC reproducibility of hybrid nanocomposites was greatly improved by introducing PAni-MWNTs.

Recently, graphene-based three-dimensional (3D) architectures have attracted a lot of attention because of their multifunctional properties. In this paper, we report on hierarchical nanohoneycomb-like CoMoO4–MnO2 core–shell and Fe2O3 nanosheet arrays on 3D graphene foam (GF) and explore their use as a binder-free electrode in supercapacitor applications. The GF was prepared by solution casting on a Ni foam scaffold. The nanohoneycomb-like CoMoO4–MnO2 core–shell nanosheet arrays were prepared by a hydrothermal method under optimized conditions. The unique core–shell network provides efficient space and a short diffusion length for faradaic reactions. The as-synthesized CoMoO4–MnO2@GF hybrid electrode exhibits excellent areal and specific capacitances of 8.01 F cm−2 and 2666.7 F g−1, respectively, at a current density of 3 mA cm−2. In addition, Fe2O3@GF was also prepared using a hydrothermal process followed by hydrogen treatment. Under optimized conditions Fe2O3@GF exhibits a high areal capacitance of 1.26 (572.7 F g−1) F cm−2. The asymmetric supercapacitor (ASC) assembled from CoMoO4–MnO2@GF as the positive electrode and Fe2O3@GF as the negative electrode delivers an excellent specific capacitance of 237 F g−1 and a high rate capability of 61%. Moreover, the as-fabricated ASC also exhibits an ultra-high energy density of 84.4 W h kg−1 and an outstanding power density of 16 122 W kg−1 as well as an exceptional capacitance retention of 92.1% after 10 000 cycles.

High-performance all-solid-state supercapacitors (SCs) have potential applications in modern electronics, such as portable and flexible electronics; however, their low specific capacity and operating voltage window limit their industrial applications. Herein, we developed a new type of zinc nickel phosphide nanosheet (Zn–Ni–P NS) arrays via a simple, scalable, and cost-effective hydrothermal and subsequent effective phosphorization technique to enhance the electrochemical performance of SCs. The hierarchical Zn–Ni–P NS array electrode exhibits an ultra-high specific capacity of ∼384 mA h g−1 at a current density of 2 mA cm−2 with excellent rate capability (79.43% of capacity retention at 50 mA cm−2), and outstanding cycling stability (∼96.45% of capacity retention after 10 000 cycles). Furthermore, the Zn–Ni–P NS//Fe2O3@NG all-solid-state asymmetric SC (ASC) delivers an ultra-high volumetric capacity of ∼1.99 mA h cm−3, excellent energy density of ∼90.12 W h kg−1 at a power density of 611 W kg−1, and extraordinary cycling stability (93.05% of initial capacity after 20 000 cycles at a high current density of 15 mA cm−2). Such enhanced electrochemical performances are ascribed to the 3D hierarchical nanostructures, porous nanonetworks, improved conductivity, and synergistic interaction between the active components of Zn–Ni–P NS arrays.

Hierarchical Zn-doped SnO2 nano-urchins decorated on RGO nanosheets were fabricated for supercapacitor applications. In this study, SnO2 nanospheres were doped with Zn2+ to tailor their electrical and morphological properties. Zn2+ doping of the SnO2 nanospheres prevented Sn clustering and thereby reduced the particle size leading to the formation of urchin-like nanostructures. These urchins with a high surface area and short transport paths can offer high capacitive performance by assembling with RGO nanosheets. The X-ray photoelectron spectroscopy and X-ray diffraction analyses confirmed the presence of SnO2 crystal planes and successful doping of the Zn2+. The incorporation of the RGO nanosheets augmented the coulombic efficiency, specific capacitance, and cycling performance. The enhancement of the capacitive behavior resulted from the synergistic effects owing to the combined properties of pseudocapacitance and double layer capacitance. The composite electrode material offered a specific capacitance of 635 F g−1 at a current density of 1 A g−1 and has a high cycling stability up to 5000 cycles with a capacitance retention of 78.4%.

An active repulsive hydrogen (H2) barrier thin film (ARHB-tfilm) was fabricated by layer-by-layer (LbL), spin and plasma sequential coatings on a poly(ethylene terephthalate) (PET) film. Protons generated by the reduction of H2 on the palladium nanolayer can be trapped in the proton-rich Nafion region by the electrical repulsive force formed at the interface of the positively charged polymer nanolayer. The multilayer ARHB-tfilms showed a significant improvement in hydrogen gas barrier properties.