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• An in-depth comparative study of three different aluminum-fluorides. • Fluorides can significantly raise the ignition and combustion performance of Al. • The promoting effect on aluminum combustion can be ranked: FG > PTFE > MgF 2. • The Al2O3 shell underwent pre-ignition reaction with fluorides. To improve the combustion characteristics of micron-sized aluminum (Al) powder, a composite powder was prepared by doping a small amount (15 wt%) of magnesium fluoride (MgF 2), polytetrafluoroethylene (PTFE), and fluorinated graphite (FG) into the aluminum powder through solution dispersion method. The physical phase composition, micro morphology, thermal reactivity, and combustion performance of the composite powders were also characterized. The findings suggest that the promoting effect of the three fluorides on aluminum combustion can be ranked in the following descending order: FG > PTFE > MgF 2. The fluorides can to erode the Al 2 O 3 shell layer directly, thus creating cracks and reaction pathways for the Al core enclosed within the shell. Moreover, the gasification of AlF 3 within the combustion products can escape from the surface of Al particles and promote the oxidation combustion of the exposed aluminum, which enhances the diffusion reaction on the active aluminum surface. [Display omitted] [ABSTRACT FROM AUTHOR]

A new solid-state 19 F magic-angle spinning NMR signal at an isotropic 19 F chemical shift of −53 ppm is measured from graphite fluoride synthesized by reaction of graphite with F 2 at temperatures above 750 K with no catalyst. Two-dimensional NMR suggests the −53 ppm 19 F NMR signal originates from covalent fluoromethanetriyl groups belonging to ordered (C y F) n bulk domains composited with the major (CF) n domains. Quantitative 19 F and 13 C NMR find y = 4.32 ± 0.64 . DFT calculations of NMR chemical shifts for unsaturated fluorographene models show that a (C 4 F) n phase with fluorine bound covalently to a single side of the carbon layer best explains the observed NMR chemical shifts. We assign the new phase to this (C 4 F) n structure, which constitutes up to 15% of the carbon in our graphite fluoride composites. The (C 4 F) n content of the composite affects bulk electrochemical properties in a manner similar to graphite fluorides produced by conventional, catalyzed fluorination processes. [ABSTRACT FROM AUTHOR]

Fluorinated single-layer diamond ("F-diamond") is a new form of two-dimensional (2D) carbon allotrope. Herein, poly(dicarbon monofluoride) (C 2 F) n which is essentially made of stacked layers of "F-diamane" has been synthesized and exfoliated in a variety of solvents to yield well-dispersed ultrathin sheets. Microscopic and spectroscopic analyses revealed that the exfoliated nanosheets retained the "F-diamane"-like structure. The experimental results are also supported by density functional theory (DFT) calculations. Image 1 • Poly(dicarbon monofluoride) (C 2 F) n was synthesized by the fluorination of graphite. • The (C 2 F) n is essentially made of stacked layers of "F-diamane". • Liquid-phase exfoliation of (C 2 F) n yielded ultrathin nanosheets. • The "F-diamane"-like structure was retained after exfoliation. • Density functional theory calculations support the experimental results. [ABSTRACT FROM AUTHOR]

• Chemically inert graphite fluoride (GiF) could be modified by concentrated sodium hydroxide aqueous solution. • Structure and compositions of modified GiF (MGiF) could be delicately regulated. • Oxygen-containing groups were introduced in MGiF. • MGiF was much easier exfoliation than unmodified GiF. Saturated or nearly saturated graphite fluoride (GiF) is difficult to be modified for their chemically inert properties. Dramatic performing conditions usually were required, and it's not facile to tune the fluorine content and to introduce reactive groups for the reported methods. In the present paper, a simple and operable method has been reported for modified GiF (MGiF) decorated with different contents of fluorine and functional oxygen groups. GiF was treated with 12˜25 M sodium hydroxide (NaOH) solution at 60°C. Besides C F and C C covalent bonds, C and O in the forms of carbonyl and hydroxyl bonds have been observed in the structure of modified GiFs. Their contents of carbonyl and hydroxyl groups and the crystalline structure of the modified GiF could be feasibly regulated by changing the concentrations of NaOH aqueous solution. MGiFs can exfoliate more easily than GiF due to the existence of the functional oxygen groups, and the exfoliated products of graphene oxyfluoride with 1˜3 layers have higher dispersion stability in N-methyl-2-pyrrolidone. [ABSTRACT FROM AUTHOR]

Aqueous zinc ion batteries (AZIBs) are considered as a promising candidate for large-scale energy storage due to its superior energy density, high specific energy, environmental friendliness and low cost. However, the dendrite growth and side reaction of zinc anode severely hinder its stability and availability. Herein, commercial glass fiber separators are modified by graphite fluoride nanoflakes via vacuum filtration (denoted as GFNs-PVDF@GF) to reinforce Zn metal anode. The GFNs-PVDF@GF separator acts as an efficient ions transport modulator to homogenize Zn2+ transport and suppress SO 4 2− flux due to strong zinc affinity and electronegativity of GFNs, thereby restraining the growth of zinc dendrite and the formation of byproducts. Accordingly, the Zn||Zn symmetric cell harvests a stable and reversible cycling for 1800 h at 1 mA cm−2 and operates at 5 mA cm−2 for over 900 h. The assembled Zn||MnO 2 full cells deliver a capacity retention of 92% after 200 cycles at 1 A g−1. Our results provide a simple and effective strategy of improving stability of zinc anode for high-performance AZIBs. • Separator modification by graphite fluoride nanoflakes (GFNs) is demonstrated. • Strong zinc affinity of GFNs acts as an efficient ions transport modulator. • Zinc dendrite and byproducts are suppressed with improving Zn anode stability. • Symmetric and full cells with GFNs-modified separator exhibit improved performance. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • High-quality fluorographene nanosheets are fabricated by microwave-assisted liquid phase exfoliation. • The as-prepared fluorographene nanosheets are comprised of no more than four monolayers. • No other side reaction and impurity elements are introduced during the exfoliation process. • Fluorographene nanosheets exhibit excellent thermal stability and remarkable lubrication behavior in oil. Abstract Fluorographene (FG), as an important class of graphene derivatives, has shown great promise in high-performance devices and lubricating materials. However, the large-scale fabrication of high-quality and impurity-free FG nanosheets still remains a main challenge. Herein, a simple liquid-phase exfoliation approach to prepare thin FG nanosheets through the preliminary intercalation of raw graphite fluoride (GrF) particles by N,N-dimethyl formamide molecules, followed by a short-time microwave treatment is reported. Atom force microscopy measurements demonstrate that as-prepared FG nanosheets are comprised of no more than four monolayers after the microwave irradiation. After exfoliation, a small amount of aromatic C C groups in the FG nanosheets are restored, which slightly lowers the F content in FG as compared with the raw GrF. Besides, no other side reaction and impurity elements are introduced during the exfoliation process as revealed by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The resultant high-quality FG nanosheets exhibit excellent thermal stability and remarkable lubrication behavior in oil, and thus can be used as a new class of graphene derivatives with the capability of large-scale fabrication for the future device and various other applications. [ABSTRACT FROM AUTHOR]

Abstract Recently, Li-rich layered structure has been used in the cathode of lithium ion batteries because of its high specific capacity. However, this structure still has some problems including large irreversible capacity loss, significant deterioration of cycling performance and poor rate property. Therefore, in our study, graphite fluoride is used to modify the surface of Li 1.14 Ni 0.133 Co 0.133 Mn 0.544 O 2 through a facile solvent evaporating method. Due to conversion reaction of the graphite fluoride, the huge discharge capacity compensation during the first discharging can improve the coulombic efficiency significantly. As reaction products, the layer of LiF@carbon reduces the interfacial reactions and increases the reversible capacity. After modification by graphite fluoride, the discharge capacities are improved by 22% from 266 to 325 mAh g−1 at 0.1 C, and 13% at 2 C. After 100 cycles, the discharge capability at 1 C is increased by 13% from 180 to 203 mAh g−1. [ABSTRACT FROM AUTHOR]

Epoxy composites with excellent toughness and strength have been successfully fabricated by direct incorporation of graphite fluoride (GrF) without using any solvent or surfactant modification. Owing to the strong interfacial interactions, the glass transition temperature of GrF/epoxy composites exhibits a significant improvement as observed by dynamic mechanical analysis. Mechanical characterizations on GrF/epoxy composites suggest that the optimal increase of tensile strength and Young's modulus is achieved at a low filler concentration of 0.5 wt%, which is attributed to the favorable level of the GrF dispersion in the epoxy matrix. A maximum toughening effect is obtained at the concentration of 1 wt% GrF in the epoxy matrix with a 1.5-fold improvement in fracture toughness. The generation of crack pinning and crack deflection in epoxy due to the existence of GrF platelets is proposed to be the main toughening mechanism. Besides, microcracks resulted from pulling out, layer breakage and interfacial debonding of GrF platelets also contribute to the improvement in the fracture toughness of GrF/epoxy composites. [ABSTRACT FROM AUTHOR]

To improve and adjust the combustion and energy output of HMX/Al, graphite fluoride (CF) as oxidizer was introduced in HMX/Al and gradient structured HMX/Al/CF was prepared by additive manufacturing technology. For HMX/Al added with CF, a significantly exothermic peak is observed ranging from 860 to 950 °C due to the reaction of Al and fluorine derived from CF decomposition, and the heat release increases by 106.63% compared to that of HMX/Al. The fourth exothermic heat increases from 161.48 to 955.25 J/g with the increased Al content from 10 to 30 wt%. Moreover, the combustion rate and pressure output of HMX/Al have been improved by introducing CF. For HMX/Al added with CF, the combustion time decreases from 10.3 to 2.5 s, which is dependent on the Al content from 10 to 30 wt%. And the highest peak pressure is 1712.2 kPa when Al content is 20 wt% in HMX/Al/CF composites. Furthermore, gradient structured HMX/Al/CF consisting of three layers with Al content of 10, 20 and 30 wt% was prepared to improve combustion and pressure output. The combustion rate and peak pressure of gradient structured HMX/Al/CF are higher than those of single structured HMX/Al/CF. The highest peak pressure (∼2.24 MPa) is obtained when the Al content of the middle layer and outer layer is 30 wt% and 20 wt% in the gradient structured HMX/Al/CF cylinder, respectively. Finally, the reaction intermediates and combustion reaction products were fully characterized to understand the enhanced effect of CF in HMX/Al. This work provides a promoting way to improve and regulate the combustion reaction performance and pressure output of HMX/Al. [ABSTRACT FROM AUTHOR]

A facile but efficient method has been developed to prepare graphene nanosheets (GNS) by reacting graphite fluoride with molten hydroxides at low temperature. Through the reaction, the resultant product shows a good dispersion in ethanol solution to self-exfoliate into GNS. The morphology and structure of GNS were characterized by microscopic and spectroscopic techniques, respectively. The results indicate that the GNS exhibit wrinkled structure with small sheet thickness and contain low quantities of oxygen functional groups arising from the displacement of fluorine atoms by hydroxyl radicals. This study provides a cost-effective route to large-scale production of soluble GNS for many potential applications. [ABSTRACT FROM AUTHOR]

The kinetic mechanism of carbon monofluoride ((CF)n) decomposition and the products generated in this reaction were studied. Given the non-isothermal differential scanning calorimetry and thermogravimetric analysis curves, nucleation mechanisms for (CF)n decomposition were proposed using model-free method. According to the extent of conversion of the reaction, the kinetic process could be described by the two-dimensional Avrami-Erofeev equation f(a)=2(1-a)[-ln(1-a)]1/2, one-dimensional Avrami-Erofeev equation f(a)=1-a and two-parameter Šesták-Berggren equation f(a)=am(1-a)n (m=-0.294, n=1.428), respectively. Due to the heterogeneity of the thermal decomposition process of (CF)n, the apparent activation energy of the thermal decomposition varied with the extent of conversion. In addition, the final decomposition products of (CF)n were confirmed to be gaseous CF4 and C2F6, and amorphous carbon via Raman spectroscopy and gas chromatography, and the volume ratio of CF4/C2F6 was found to be approximately 12. [ABSTRACT FROM AUTHOR]

Highlights: [•] The polypropylene/polydimethylsiloxane/graphite fluoride (PP/PDMS/GF) composites are prepared. [•] The study of superhydrophobicity showed that the WCA reaches 148° with a sliding angle 6°. [•] Sandpapering and addition of GF can apparently increase superhydrophobicity. [ABSTRACT FROM AUTHOR]

Abstract: Fluorine compounds are quite useful as energy conversion materials, in particular as primary and secondary lithium battery materials. Primary lithium battery with graphite fluoride cathode was commercialized in 1973, based on the research on graphite fluoride. Since then, it has been shown that fluorine compounds are useful and attractive materials for lithium batteries. The present account paper reports the historical aspects and update topics on fluorine compounds such as graphite fluorides, fluorine–graphite intercalation compounds and organo-fluorine compounds as energy conversion materials. Surface modification by fluorine is also reported. [Copyright &y& Elsevier]

A series of layered inclusion compounds based on fluorinated graphite CF ( x≤1) was obtained by a room temperature synthesis. Inclusion compounds (intercalates) of fluorinated graphite matrix were n-hexane and dichloromethane, i.e., organic guest molecules that differ in size and symmetry. The changes in CF stoichiometry are shown to have a decisive effect on magnetic properties of produced complexes. The spin concentration decreases with the increase of fluorine content in fluorocarbon matrix. All samples have groups of correlated spins; at the temperatures 1.75-5 K nonlinear magnetization is observed, indicating a high-spin state. Application of the Langevin formula shows that the clusters consist of 10-20 interacting spins. [ABSTRACT FROM AUTHOR]

Abstract: Graphite fluoride has been generally considered chemically inert against strong alkalis under ambient conditions. In the present study we demonstrate that treatment of graphite fluoride with eutectic NaOH–KOH mixture at 250°C induces dramatic structural and textural changes in the solid as evidenced by XRD, FT-IR, Raman, UV–vis absorption and fluorescence and microscopy techniques (TEM, AFM). The reaction proceeds in the molten state leading to water-soluble, graphitized carbon particles which unlike graphite fluoride, adopt a variety of morphologies, like platy, tetragonal, triangular, discoid and spherical. The resulting carbon particles are dispersible in water and fluoresce under UV excitation. [Copyright &y& Elsevier]

The energy level structure of fluorinated graphite intercalation compounds C2FxBr0.01· yCH3CN ( x = 0.49–0.87, y = 0.084–0.136) has been studied by X-ray photoelectron spectroscopy providing the information on the electronic structure of compounds in question. The analysis of variations of the binding energy of core levels C1 s, F1 s, and O1 s opens the possibility to explore the nature of the chemical bond C-F in the fluorographite matrix with a varying degree of fluorination, as well as to model the structure of these compounds. The examination of decomposition results of spectra into components has revealed the occurrence of C-F fragments, carbon atoms not bonded directly to fluorine atoms, and “graphite-like” areas, whose contribution to the overall structure increases with the degree of matrix fluorination decreasing. The presence of oxygen was considered from the viewpoint of surface phenomena characteristic of low-temperature carbon materials. [ABSTRACT FROM AUTHOR]

By the first-principles calculation, we show that graphite fluorides have a potential for application as optical devices with near ultraviolet light emission. [ABSTRACT FROM AUTHOR]

Reactive materials consisting of aluminum (Al) and fluorine-containing oxidizers have been extensively developed owing to high energy density and potential applications in propellants and explosives. Herein, graphite fluoride (CF) as a new fluorine-containing oxidizer was introduced to construct nano-Al based reactive materials. Systematic investigation and comparison were executed on exothermic reaction behavior and combustion performance of nano-Al/CF and nano-Al/polytetrafluoroethylene (PTFE) based reactive materials. The energy output and exothermic peak of nano-Al/CF were approximately 2367 J/g and 641 °C, which were 300 J/g and 85 °C higher than those of nano-Al/PTFE, respectively. The effects of nano-Al/CF mass ratio and packing density on burning rates were examined to fully understand combustion reaction and flame propagation behavior. Nano-Al/CF exhibited excellent burning rate (1670 m/s), much higher than that of nano-Al/PTFE (930 m/s). More interestingly, flame splitting phenomenon including three distinct flame regions was observed on the critical position with the highest burning rate for nano-Al/CF with the mass ratios of 25/70 and 30/75. The burning rate of nano-Al/CF increased and then decreased with the packing densities ranging from 20.87% to 53.47% TMD. The dominating combustion reaction products (AlF 3 and C) were further determined to figure out the reaction mechanism. These results demonstrated that CF as fluorine-containing oxidizer to construct reactive materials has potential applications in propellants, explosives and pyrotechnics. [ABSTRACT FROM AUTHOR]

As a graphite derivative, graphite fluoride (GrF) has a remarkable fracture toughness improvement effect on epoxy materials. The fracture toughness variation of the epoxy could exert an influence on the low velocity impact resistance of the corresponding carbon fiber reinforced polymer (CFRP) composite. Therefore, the dependence of the low velocity impact resistance of the incorporated CFRP on the GrF content is worth analyzing. Here, different contents of GrF were applied to incorporate CFRP laminates and planned to find the optimal GrF content, in turn leading to the best impact resistance. Using a drop-weight impact test, the load vs. time curves and load vs. displacement curves were obtained. The incipient damage loads and maximum loads of various GrF contents of the samples were compared carefully. The absorbed energies during the impact process were calculated. The trend of absorbed energy decreased up to the 1 wt% sample, then increased significantly with the rise of GrF content. This deflection behavior can be explained by the combination of crack pinning, crack deflection and crack propagation, due to the rise in GrF content. Through the ultrasonic C-scan evaluation, the delamination areas of different GrF content of samples were measured. The trend of delamination area variation was accordant with the trend of absorbed energy variation. This presents a demonstration of the correlation between the absorbed energy and the damage level. The SEM images of the fracture surfaces were analyzed for the deflection behavior of the fracture toughness with various GrF contents. The plot of residual compression strength versus GrF content further indicated the 1 wt% was the optimal content at which the incorporated GrF endowed the most impact-resistant property to the CFRP laminates. [ABSTRACT FROM AUTHOR]

Graphite fluoride‐launched graphene functionalization has attracted increasing interest in recent years. Highly basic nucleophiles are normally employed for ultrastrong CF bonding. However, frequently, an appreciable majority of C–F units of graphite fluoride are reductively eliminated, leading to low functionalization degrees. It is hypothesized that graphite fluoride could likely be functionalized to a larger degree by lowering the basicity of the nucleophiles. Herein, ultraweakly basic NH3·H2O is adopted as a nucleophile to react with extremely inert graphite fluoride, and the resulting reaction affords amino/hydroxyl cofunctionalized graphene (NH2–G–OH). As expected, the NH2/OH functionalization degree and the ratio of substituted C–F units to reduced ones reach high values of 0.34 and 1.62, respectively. Due to the dual energy‐storage mechanisms of the electrochemical double‐layer capacitance coupled with Faradaic pseudocapacitance, the NH2–G8–OH‐based all‐solid‐state supercapacitors are flexible and robust and deliver state‐of‐the‐art capacitive characteristics, while exhibiting high rate capability and electrochemical cycling stability. In addition, NH2/OH moieties remain highly reactive to be post‐functionalized by versatile electrophiles, not only achieving an umpolung of graphite fluoride, but also enabling NH2–G8–OH a competitive alternative to monopolistic GO, and opening up an innovative pathway for development of high‐performance graphene derivatives amenable to multifarious applications. [ABSTRACT FROM AUTHOR]

The theoretical self-discharge rate of Li/MnO 2 primary batteries is less than 1% per year, but the actual self-discharge rate is ∼8% per year, and the shelf life of the coin batteries (such as CR2016) is only 5 years. In this paper, MnO 2 mixed some (CF x) n as cathode material in Li/MnO 2 primary batteries, not only can effectively reduce self-discharge rate, but also improve capacity density and heighten discharge plateau voltageafter storage. After storage at 25 °C for 60 days, the specific charge capacity of MnO 2 decreases from 293 mAh g−1 to 283 mAh g−1, while MnO 2 -(CF x) n increases from 312 mAh g−1 to 326 mAh g−1. After storage for 30 days at 45 °C, the self-discharge rates of MnO 2 and MnO 2 -(CF x) n are 9.21% and 1.92% (0.5 mA cm−2), respectively. During storage and the initial stage of discharge, F in MnO 2 -(CF x) n can act on Mn–O bond and some C–F semi-ionic bonds form when Li+ insert into (CF x) n layers, these change the unit cell parameters of MnO 2 and the utilization of MnO 2 increases. [ABSTRACT FROM AUTHOR]