“…The I D /I G = 0.73 for graphene turns large after exfoliation, which is probably attributed to the edge defect and the disorder of graphene compared with that for compact graphite. The shift of 2D peak from 2723 cm −1 for graphite to 2701 cm −1 for graphene also indicates that the layer number in the graphene is normally less than 5 . To sum up, the resultant few‐layer graphene nanosheets have few defects and retain a complete hexagonal lattice.…”
Although a polymer film capacitor releases a huge power density in pulse time, its electrical capability is limited by the low energy density for the embedded hybrid device. It is still a challenge to increase the energy density and retain high charge–discharge efficiency of the polymer film. High dielectric properties and high energy density are obtained in the uniaxial stretching poly(vinylidene fluoride‐chlorotrifluoroethylene) (P(VDF‐CTFE)) nanocomposite incorporated with few‐layer graphene, which is exfoliated with the assistance of a fluoro hyperbranched polyethylene‐graft‐poly(trifluoroethyl methacrylate) (HBPE‐g‐PTFEMA) copolymer via CH—π noncovalent interactions. The graphene/P(VDF‐CTFE) nanocomposite film is prepared via solution casting, and then, the in‐plane orientation of nanosheets is accomplished by uniaxial deformation. The relative content of the β phase reaches 96.0% in 0.8 vol% nanocomposite due to the combination of improved compatibility and the alignment of macromolecular chains. The energy density of a 0.1 vol% graphene/P(VDF‐CTFE) film achieves 9.5 J cm−3 as E = 400 MV m−1, which is attributed to the large‐content electroactive phase and interfacial polarization. The P(VDF‐CTFE) nanocomposite incorporated with aligned graphene exhibits a promising energy storage capability, which indicates that the orientation of nanosheets is an effective solution to enhance the energy density of the polymer film with large charge–discharge efficiency.
“…The I D /I G = 0.73 for graphene turns large after exfoliation, which is probably attributed to the edge defect and the disorder of graphene compared with that for compact graphite. The shift of 2D peak from 2723 cm −1 for graphite to 2701 cm −1 for graphene also indicates that the layer number in the graphene is normally less than 5 . To sum up, the resultant few‐layer graphene nanosheets have few defects and retain a complete hexagonal lattice.…”
Although a polymer film capacitor releases a huge power density in pulse time, its electrical capability is limited by the low energy density for the embedded hybrid device. It is still a challenge to increase the energy density and retain high charge–discharge efficiency of the polymer film. High dielectric properties and high energy density are obtained in the uniaxial stretching poly(vinylidene fluoride‐chlorotrifluoroethylene) (P(VDF‐CTFE)) nanocomposite incorporated with few‐layer graphene, which is exfoliated with the assistance of a fluoro hyperbranched polyethylene‐graft‐poly(trifluoroethyl methacrylate) (HBPE‐g‐PTFEMA) copolymer via CH—π noncovalent interactions. The graphene/P(VDF‐CTFE) nanocomposite film is prepared via solution casting, and then, the in‐plane orientation of nanosheets is accomplished by uniaxial deformation. The relative content of the β phase reaches 96.0% in 0.8 vol% nanocomposite due to the combination of improved compatibility and the alignment of macromolecular chains. The energy density of a 0.1 vol% graphene/P(VDF‐CTFE) film achieves 9.5 J cm−3 as E = 400 MV m−1, which is attributed to the large‐content electroactive phase and interfacial polarization. The P(VDF‐CTFE) nanocomposite incorporated with aligned graphene exhibits a promising energy storage capability, which indicates that the orientation of nanosheets is an effective solution to enhance the energy density of the polymer film with large charge–discharge efficiency.
“…The quality of samples was studied using Raman spectroscopy and is compared with graphite shown in figure 6 a,b [ 40 ]. Figure 6 a shows the Raman spectra of the high-pressure exfoliated graphene, which consists of D band, G band and two-dimensional band related to various vibrational modes.…”
Section: Resultsmentioning
confidence: 99%
“…The intensity ratio of D and G bands is evaluated as 0.85 for exfoliated graphene, which is much higher than that of the natural graphite (0.05), which features the exfoliation of graphite. Various parameters of Raman spectra of exfoliated graphene, in comparison with standard graphite [ 40 ], are tabulated in table 1 . Figure 6 ( a ) Raman spectra of high pressure exfoliated graphene.…”
In recent years, graphene has found its use in numerous industrial applications due to its unique properties. While its impermeable and conductive nature can replace currently used anticorrosive toxic pigments in coating systems, due to its large strength to weight ratio, graphene can be an important component as a next-generation additive for automotive, aerospace and construction applications. The current bottlenecks in using graphene and graphene oxide and other two-dimensional materials are the availability of cost-effective, high-quality materials and their effective incorporation (functionalization and dispersion) into the product matrices. On overcoming these factors, graphene may attract significant demands in terms of volume consumption. Graphene can be produced on industrial scales and through cost-effective top-down routes such as chemical, electrochemical and/or high-pressure mechanical exfoliation. Graphene, depending on end applications, can be chemically tuned and modified via functionalization so that easy incorporation into product matrices is possible. This paper discusses different production methods and their impact on the quality of graphene produced in terms of energy input. Graphene with an average thickness below five layers was produced by both methods with varied defects. However, a higher yield of graphene with a lower number of layers was produced via the high-pressure exfoliation route.
This article is part of a discussion meeting issue ‘A cracking approach to inventing new tough materials: fracture stranger than friction’.
“…Moreover, the efficiency of the DSC using the 3D CFG CE was even better than that of the DSC using the Pt CE (7.5%). Additionally, graphenes with various morphologies such as cryogels, nanoflakes, and nanoplatelets were also used as CEs, and the corresponding DSCs achieved PCE values of 8.70%, 6.08%, and 6.23%, respectively . The Liu group described specific graphene organogels (GOGs) converted from a graphene hydrogel (GH) by a simple solvent‐exchange approach .…”
Section: Carbon Counter Electrode In the Dye‐sensitized Solar Cellmentioning
Developing highly effective and stable counter electrode (CE) materials to replace rare and expensive noble metals for dye‐sensitized and perovskite solar cells (DSC and PSC) is a research hotspot. Carbon materials are identified as the most qualified noble metal‐free CEs for the commercialization of the two photovoltaic devices due to their merits of low cost, excellent activity, and superior stability. Herein, carbonaceous CE materials are reviewed extensively with respect to the two devices. For DSC, a classified discussion according to the morphology is presented because electrode properties are closely related to the specific porosity or nanostructure of carbon materials. The pivotal factors influencing the catalytic behavior of carbon CEs are also discussed. For PSC, an overview of the new carbon CE materials is addressed comprehensively. Moreover, the modification techniques to improve the interfacial contact between the perovskite and carbon layers, aiming to enhance the photovoltaic performance, are also demonstrated. Finally, the development directions, main challenges, and coping approaches with respect to the carbon CE in DSC and PSC are stated.
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