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In order to prepare self-standing and flexible slow neutron reflectors made of graphite fluoride (GF) with high contents of (C2F)n structural phase, graphite foils of different thicknesses were used as starting materials for gas (F2)/solid fluorination. The maximal interlayer distance of GF was obtained with this phase thanks to the stacking sequence FCCF/FCCF; this is mandatory for the efficient reflection of slow neutrons. 71 and 77% of the (C2F)n phase were achieved for graphite foils with thicknesses of 1.0 and 0.1 mm, respectively. The interlayer distances were 8.6 Å as expected. The fluorination conditions (static mode, a long duration of 24 h, annealing in pure F2 gas for 24 h, and temperatures in the 390–460 °C range) were adapted to large pieces of graphite foils (7 × 7 cm2) in order to both avoid exfoliation and achieve a homogeneous dispersion of fluorine atoms. This process was also efficient for thinner (0.01 mm thick) graphitized graphene oxide foil. 56% of the (C2F)n phase and an interlayer of 8.6 Å were achieved for this foil when fluorination was performed at 430 °C. Whatever the nature and the thickness of the foil, their flexibilities are maintained. [ABSTRACT FROM AUTHOR]

To elucidate how different spatial oxygen-containing groups influenced lithium-storage performance of graphene matrix, and further establish a clear structure-performance relationship, graphene framework was strategically functionalized with carboxylate and sulfonate groups and oxygen-free aniline ones as a reference. Due to maximum lithiation effect, spatially sulfonate functionalized graphene delivered the best electrochemical performances in lithium-ion batteries. [Display omitted] Graphene derivative materials are widely used as anode component in lithium-ion batteries. However, there is still a lack of reliable and foresighted guides helpful for designing high-performance graphene-based electrode materials. To this end, we strategically chose challenging graphite fluoride as starting material for the derivatization of graphene in order to exclude interference factors. As a result, graphene framework was functionalized with oxygen-containing carboxylate and sulfonate groups and oxygen-free aniline units at a similar functionalization degree. Due to the strong effect of lithiation, out-of-plane p -aminobenzoic acid blocks boosted the lithium-storage capacity of graphene matrix to 636 mAh g−1 at 0.1 A/g, and sulfanilic acid blocks maximized this value to 873 mAh g−1. Sadly, oxygen-free aniline functionalized graphene material only delivered a specific capacity of 88 mAh g−1. Meanwhile, spatial lithiated carboxylate and sulfonate units endowed graphene framework with better rate capability and cycling stability. Such a structure-performance relationship established herein was beneficial for the design and preparation of high-performance graphene derivative electrode materials. [ABSTRACT FROM AUTHOR]

Discovery of new electrochemical redox motifs is essential to expand the design landscape for energy-dense batteries. We report a family of fluorinated reactants based on pentafluorosulfanyl arenes (R-Ph-SF5) that allow for high electron-transfer numbers (up to 8-e−/reactant) by exploiting multiple coupled redox processes, including extensive S–F bond breaking, yielding capacities of 861 mAh·greactant−1 and voltages up to ∼2.9 V when used as catholytes in primary Li cells. At a cell level, gravimetric energies of 1,085 Wh·kg−1 are attained at 5 W·kg−1 and moderate temperatures of 50 °C, with 853 Wh·kg−1 delivered at >100 W·kg −1, exceeding all leading primary batteries based on electrode + electrolyte (substack) mass. Voltage compatibility of R-Ph-SF5 reactants and carbon monofluoride (CFx) conversion cathodes further enabled investigation of a hybrid battery containing both fluorinated catholyte and cathode. The hybrid cells reach extraordinarily high cell active mass loading (∼80%) and energy (1,195 Wh·kg−1), allowing for significant boosting of substack gravimetric energy of Li−CFx cells by at least 20% while exhibiting good shelf life and safety characteristics. [ABSTRACT FROM AUTHOR]

Graphites covalently intercalated with fluorine to form (C 2 F) n structural type compounds shows a dramatic increase of the interlayer distance up to by a factor of almost 3 to reach ∼9 Å. Such graphite fluoride compounds containing only carbon and fluorine offer the rare opportunity to bridge the so-called gap in the reflectivity of neutron reflectors. Slow neutron reflectors are of great interest in designing neutron sources as well as in fundamental and applied science; they require synthesizing high thermal and chemical compound stability graphite fluorides. In this work, a new strategy is proposed for synthesizing (C 2 F) n compounds in a well-controlled method. Our results show that the outcome (C 2 F) n has a covalent character with only sp3 hybridized carbon atoms. Moreover, C–F bonds in the fluorocarbon sheets and CF 2 groups on the sheet edges lead to the desired stability and hydrophobic character. A dedicated home-made neutron diffractometer was built for measurements of double-differential neutron cross sections of crystals with specific large interlayer distances found in (C 2 F) n compounds. We demonstrate that the synthesized fluorine intercalated graphites developed effectively cover the gap in the reflectivity for the new generation of neutron reflectors. [Display omitted] [ABSTRACT FROM AUTHOR]

The high energy density of fluorinated graphite (CF x) based lithium primary battery has aroused tremendous attention. However, the nonconductive CF x always induces high interface impedance and low power density. Herein, the carbon conductive network is generated by thermal treatment of resorcinol/formaldehyde (RF) resin on CF x and RF resin spheres (RF RSs), a conductive carbon layer coats on CF x surface, the electrical conductivity of CF x is improved. The oxygen functional groups in incomplete carbonized RF RSs also dedicate to the electrochemical performance of CF x. When different mass ratios of CF x /RF RSs are employed, the cathodes exhibit improved rate performance and voltage plateaus, and the initial voltage delays observed in CF x are significantly reduced. Notably, CF x /RF RSs−13 cathode delivers an impressive discharge capacity of 843.8 mAh g−1 with a voltage plateau of 2.68 V at 10 mA g−1. This leads to the maximum energy density of 2174.9 Wh kg−1 and a peak power density of 18600 W kg−1. Additionally, CF x /RF RSs−13 cathode demonstrates commendable electrochemical stability across a wide temperature spectrum (−20–70 °C). Given these superior electrochemical attributes, the CF x /RF RSs combination holds significant promise for deployment in high-power devices and for standard operations under extreme temperature conditions. • Carbon conductive network is induced by heat treatment of RF resin on CF x and RF RSs. • Oxygen functional groups in RF RSs also make for electrochemical performance of CF x. • CF x /RF RSs−13 gives peak energy and power densities of 2174.9 Wh kg−1, 18600 W kg−1. • CF x /RF RSs−13 demonstrates commendable electrochemical stability from −20 to 70 °C. [ABSTRACT FROM AUTHOR]

• 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]

The damping properties of fluorinated polyacrylate (FPA) composites with expanded graphite (EG) partially substituted for mica as fillers have been studied. EG was prepared by a rapid expansion method by microwave (MW) irradiation. The effects of the EG and natural graphite (NG) as partial substitutions for mica and the blending of epoxy (EP) resin with the polyacrylate emulsion on the damping performance of the composites was investigated with dynamic mechanical analysis (DMA). The results showed that adding EG as a partial substitute for the mica improved the intensity of the loss peak of the DMA tanδ and broadened the corresponding high loss factor (tanδ > 0.3) temperature range of the PA/EP composites. In comparison with NG or the mica, EG was more efficient in improving the damping properties of the composites. When the weight content of EP was 4% and EG was 6%, tanδ reached the maximum value of 2.16, and the corresponding temperature range with tanδ > 0.3 was about 80 °C. [ABSTRACT FROM AUTHOR]

Fluorinated graphene-like materials are currently attracting much attention due to the tuning of their properties by changing the fluorine content and pattern on the graphene lattice. In this work, we report the redshift of absorption bands and the suppression (increase) of green (yellow-orange) photoluminescence (PL) in the spectra of transparent CF x crystallites as x decreases from ∼0.44 to ∼0.33. Time-dependent density functional theory (TDDFT) calculations reveal that the aromatic regions and polyene chains in the CF x layers are mainly responsible for the optical absorption of the samples in the ultraviolet and visible regions, respectively. The electron-hole recombination within branched aromatic rings or long carbon chains produces orange-red emission, while green-yellow PL is due to transitions of excited polyene electrons to half-occupied levels of aromatic carbon. Our results show that the optical properties of partially fluorinated graphite layers are determined by the size and shape of the remaining sp2 carbon regions, which can be varied by changing the fluorination conditions. [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]

A graphite-mediated microwave-based strategy was used for solid-state exfoliation of graphite fluoride in a few seconds, followed by a simple yet efficient separation to obtain exfoliated materials based on the density difference between graphite and graphene fluoride in solvent. The microwave-exfoliated graphene fluoride was a few layers thick and electrically conductive. The electrochemical testing of pouch-cell supercapacitors assembled by using the exfoliated graphene fluoride electrodes and a novel microemulsion-based electrolyte showed reasonable performance with typical electrical double-layer capacitance behavior and good rate capability (gravimetric specific capacitance: 3.2 F g−1 at 500 mA g−1 and 3.1 F g−1 at 5000 mA g−1). The BET specific surface areas of the as-exfoliated graphene fluoride are ~60–80 m2 g−1, which could be increased by activation using this simple yet versatile microwave-based method for further improvements on the electrochemical performance. [ABSTRACT FROM AUTHOR]

Electrocatalytic nitrogen reduction reaction (eNRR) is a sustainable alternative to the traditional Haber–Bosch process due to its eco‐friendly nature and capability of utilizing renewable energy. However, its low Faradic efficiency (FE), caused by the excessive adsorption and reduction of protons, has been regarded as the main challenge, which leads to low ammonia yield as well. Herein, a carbon‐supported iron electrocatalyst is reported, which is fabricated by low‐temperature (300 °C) potassium vapor reduction of FeF3‐intercalated graphite fluoride, for efficient electrochemical nitrogen reduction. The strategy enables the unique formation of exposed Fe nanoparticles uniformly anchored on graphene and in situ doped with fluorine heteroatoms. These specific features can alter the electronic configuration of the Fe nanoparticles, leading to strong surface polarization that boosts nitrogen absorption capability for eNRR, resulting in high FE (41.6%) and ammonia yield rate (53.3 μg h‐1 mg‐1) simultaneously. First‐principle calculation attributes this enhanced eNRR capability to more empty orbitals carried by the Fe atoms through the electron transfer with F dopant and substrate. As a versatile strategy for synthesizing various ultrafine and highly dispersed metal nanoparticles on the carbon support, this work might shed light on rational designing essential electrocatalysts with effective electronic structure manipulation. [ABSTRACT FROM AUTHOR]

High-concentration electrolytes (HCEs) are favored in graphite cathode-based dual-ion batteries (DIBs) due to their high oxidative stability and good interphase compatibility with both anode and cathode. Although a localized high-concentration electrolyte (LHCE) with the similar solvation structure as HCE is proposed for graphite cathode by adding weakly solvated fluorinated cosolvents, the balance between salt concentration and fluorinated cosolvent has not been investigated. Herein, various electrolytes were prepared by introducing tris(2,2,2-trifluoroethyl) phosphate (FTEP) into the HCE composed of potassium bis(fluorosulfonyl)imide (KFSI) and triethyl phosphate (TEP), and the moderate concentrated electrolyte at the TEP/FTEP volume ratio of 5:1 can stabilize K/graphite DIBs with the capacity of 45 mAh g−1 after 300 cycles at 0.5 A g−1. The abundant ion–solvent complexes as HCE and the entrance of FTEP contribute to building stable FSI−-derived cathode/electrolyte interphase with the KF-rich inner layer. Importantly, FTEP replaces partial TEP solvents to coordinate with FSI−, enhancing the electrolyte oxidative stability, whereas their weak interaction further suppresses the solvent co-intercalation. As a proof, this electrolyte enables high output voltage (3.75 V) and good cyclability of dual-ion full cells coupled with tellurium anode. This work will promote the development of fluorinated cosolvent-modified LHCEs for high-performance DIBs. The balance between salt concentration and fluorinated cosolvent is discovered for graphite cathode with high-rate capacity and good cyclability. Abundant ion–solvent complexes and the participation of fluorinated cosolvent facilitate building anion-derived cathode/electrolyte interphase. The coordination of fluorinated cosolvent with anions to replace some solvent molecules enhances the electrolyte oxidative stability, whereas the weak interaction further suppresses the solvent co-intercalation. [Display omitted] • Graphite cathode exhibits high-rate capacity by introducing FTEP as fluorinated cosolvent in HCE. • Abundant ion–solvent complexes and FTEP's participation help build anion-derived and F-rich CEI. • Weak interaction between FTEP and anion suppresses solvent co-intercalation into graphite cathode. [ABSTRACT FROM AUTHOR]

Rechargeable batteries based on graphite are considered as promising alternatives for energy storage applications. The charge/discharge mechanisms of these batteries results from the intercalation and de-intercalation driven electrochemically by the atoms or molecules of the electrodes in contact with a liquid electrolyte. These solutions are often complex systems engineered to stabilize and allow the transport of the evolving moieties. In this article, we isolate the effect on the graphite structure of a chemical component of novel electrolytes, the aluminum fluoride (AlF 3), by dosing this pure compound in the gas phase over high oriented pyrolitic graphite (HOPG) substrates at 10−9 mbar and 300 K. We performed an extensive experimental study involving surface characterization and beam analysis techniques, and developed a model of the sorption substantiated in ab-initio calculations. We found a preferential interlaminar absorption when dosing in the direction transversal to the carbon planes. The intercalation in the HOPG is spontaneous and non-reactive, and increases the interplanar spacing by 20%. A charge transfer of 0.65 e− per formula from graphite to AlF 3 is calculated for the intercalate. Since the absorption depends on the roughness of the substrate we may infer that the intercalation proceeds through the step-edges. These features may contribute to the development of novel quasi-2D devices for special applications. [Display omitted] ● We isolate the effects of the AlF 3 over the crystalline structure and chemistry of HOPG by studying the system AlF 3 /HOPG in UHV by STM, XPS, RBS, and using DFT calculations to build an absorption model. ● The AlF 3 aggregates diffuse into the substrate, separating the carbon layers locally, and in turn generate changes in the density of electronic states of neighboring regions. ● The AlF 3 and HOPG retain their chemical identity ruling out the formation of metallic Al formation on the surface and any type of covalent bond between C and AlF 3 ● Surface defects and rsubstrate roughness are parameters that control the thickness of the fluoride intercalates. ● The calculated intercalation energy favours this process over adsorption, predicting a value of 4.41 V for its deintercalation potential. [ABSTRACT FROM AUTHOR]

In a typical Al–air battery, the air cathode functions as a deposition substrate for discharge products while allowing O2 entrance. Herein, we present an air electrode that simultaneously allows two discharge processes. The function of the metal–air battery is enabled by using porous carbon nanotube (CNT)-based tissue substrates. In contrast, the fluorinated graphite (CFx) coating on the CNT substrate provides an additional discharge process, enhancing discharge capacity. Two CFx loadings are investigated, and their performances are compared with that of a pristine CNT tissue. Electrochemical evaluations, including half- and full-cell measurements, are performed to examine the effect of the coating layer thickness on the ability of the cell to function at high discharge rates. High CFx loadings improved the cell performance and increased discharge capacities (an increase of ~ 3 mAh cm−2 for the 0.1 mA cm−2 and ~ 5 mAh cm−2 for the 0.25 mA cm−2 evaluations) until reaching high discharge loads. When applying 0.5 mA cm−2, the additional layer restricts O2 access into the cell, preventing the metal–air battery from functioning as intended. High-resolution scanning electron microscopy and energy-dispersive X-ray spectroscopy are used to characterize the discharge products deposited on this unique electrode. [ABSTRACT FROM AUTHOR]

[Display omitted] Low energy density is the major obstacle for the practical all-solid-state supercapacitors, which may be raised by the combination of the pseudocapacitance with the electrochemical double-layer capacitance. Although graphene and polyaniline have been demonstrated two effective materials, the synthetic route of graphene and their hybrid mode largely dictated the capacitive performances and cyclability of graphene/polyaniline nanocomposites. Herein , we employed commercial graphite fluoride as the precursor to obtain graphene with a well-preserved carbon lattice. After graphite fluoride functionalization by p -phenylenediamine (p PDA) and in situ oxidative polymerization of anilines, polyaniline (PANI) chains were covalently attached to graphene framework through p PDA bridges. Multiple characterizations were performed to confirm the covalent binding mode between graphene scaffolds and PANI partners, and electrochemical tests unraveled the as-prepared G– p PDA–PANI triads delivered a gravimetric capacitance as high as 638F g−1 and a further amplified volumetric capacitance (up to 759F cm−3). The bendable all-solid-state supercapacitors yielded an encouraging energy density of over 18 W h L−1 at a power density high to 5,950 W L−1, while exhibiting an exceptional rate capability, cycling stability and mechanical flexibility. [ABSTRACT FROM AUTHOR]

• Al/B/CF microspheres have been prepared through self-assembly in emulsion. • Spherical Al/B/CF fuel exhibits high energy density and superior reactivity. • The combustion reaction of single Al/B/CF microsphere are studied for the first time. • The CF content and Al/B mass ratio have significant effects on combustion behaviors. Aluminum (Al) is one of the most widely used metal fuels in the fields of automotive airbags, solid propellants, explosives and pyrotechnics. Unfortunately, it is hard to meet further demand of practical applications owing to the comparatively low calorific value. Herein, graphite fluoride (CF) and boron (B) are employed to construct Al/B/CF microspheres through self-assembly in emulsion to obtain high energy density and significantly improved combustion performance resulted from synergistic reaction between Al and B reacted with fluorine. The Al/B/CF microspheres with pore structure have uniformly distribution of components and the average size range from 60 to 600 μm. Based on the experimental results, CF content and Al/B mass ratio have significant important effects on the combustion behavior and pressure output. The highest burning rate (301.74 m/s) and pressurization rate (77.78 MPa/s) are obtained for the Al/B/CF microspheres with CF content of 50 wt% and Al/B mass ratio of 3 to 1, respectively. Furthermore, the combustion reaction process of single Al/B/CF microsphere are studied for the first time to understand the synergistic reaction between high reactivity of Al and high energy of B reacted with fluorine. This work demonstrates that introducing CF and B to construct Al/B/CF microspheres is an efficient strategy to achieve high energy density and reactivity for the practical applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nitrogen doped sub-fluorinated graphite with larger layer spacing material. • Simple and effective modified method without high temperature or pressure. • Fluorinated graphite can obtain a power density of 40.23 kW kg−1. • The dependence of cathode material structure, LiF and cathode swelling is provided. Lithium/carbon fluorides batteries own a high theoretical energy density of 2180 Wh kg−1 and exceptional shelf life, but poor electrode kinetics, low electronic conductivity of cathode, and cathode swelling during discharge. In this work, fluorinated graphite is modified by a controllable solvent treatment using N-methyl-2-pyrrolidone at medium temperature (50 ∼ 90 °C). The modified fluorinated graphite is doped with nitrogen atoms and owns increased interlayer spacing and electrochemical active semi-ionic C F bonds, providing a higher conductivity and facilitating the diffusion of Li+ or solvent Li+. The maximum power density of the modified fluorinated graphite is 40.23 kW kg−1 at 25C. To elucidate the cathode swelling of the fluorinated graphite, in-situ confocal optical microscope and in-situ X-ray diffraction are conducted for the first time. It is found that the formation and accumulation of crystalline LiF during discharge, as well as the interlayer spacing of fluorinated graphite, are related to the cathode swelling in liquid electrolyte. [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]

[Display omitted] • Fluorinated graphite (FG) CF 0.4 is irradiated with a synchrotron white beam. • XPS spectra showed little change in the composition of the irradiated layers. • Under photon action, HNO 3 , NO 2 , NO, and N 2 decompose inside the FG matrix. • Embedded NO x molecules stimulate FG defluorination and vacancy formation. • Nitrogen from NO x molecules saturates the boundaries of vacancies. Layered fluorinated graphite material can become an efficient nanoreactor for photochemical reactions. In this work, we compared the photochemical behavior of partially fluorinated graphite (FG) and FG containing nitrogen oxides in the interlayer space (NO x @FG) under the action of a high-intense polychromatic photon beam from the synchrotron radiation source BESSY II. Analysis of the chemical and electronic states of the samples was performed using X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure spectroscopy. Density functional theory calculations were used to interpret and analyze the experimental data. It was found that nitrogen oxides promote the photo-induced degradation of the FG matrix, namely, its partial defluorination, formation of vacancies and doping with nitrogen, while the empty FG had a high photoresistance to synchrotron radiation. The results obtained can be used in the development of new approaches to the modification of graphene layers and in the creation of photostable materials for optical elements. [ABSTRACT FROM AUTHOR]

Membrane distillation (MD) relies on superhydrophobic membranes that must achieve the competing goals of high liquid entry pressure (LEP) and high permeability. In this study, we developed the first superhydrophobic composite electrospun asymmetric membrane using fluorinated graphite (FG). We also provided among the first comparisons of the relative benefits of membrane asymmetry and composite coatings via 3D electrospinning and spraying. FG particles increased the roughness and reduced the zeta potential of the membranes. Superhydrophobic composite membranes had a contact angle of 157° (sliding angle of 7°) and an LEP of 327 kPa. Long-term MD testing revealed that FG particles could increase MD's sustainability while decreasing membrane wetting. Vacuum-assisted air gap membrane distillation (V-AGMD) showed that the composite asymmetric membrane outperformed the non-asymmetric version (composite nanofiber) membrane by 21 % in average water flux and 25 % in average thermal efficiency because of the asymmetric structure of the membrane. The numerical model developed for the V-AGMD system also successfully predicted the water flux generated experimentally from the composite nanofiber and composite asymmetric membranes. Our results confirmed that electrospun asymmetric FG membranes with high contact angle, low sliding angle, high permeability, and high gained output ratio (GOR) would be promising candidates for sustainable MD. [Display omitted] • The composite asymmetric membrane varied fiber size and coatings. • Fluorinated graphite coating shows superhydrophobicity and small sliding angle. • Surface charge of membrane reduced by fluorinated graphite • Electrospun asymmetric structure greatly improves the flux and thermal efficiency. [ABSTRACT FROM AUTHOR]

Intercalation compounds of fluorinated graphite that form when graphite interacts with a strong fluorinating agent have been known for several decades. However, there was not enough understanding about their structures and outstanding stabilities, given that guest molecules contained in them are very active fluoroxidants. In this study, we build a structural model of an ordered crystal of the stage-II intercalation compound C 2 F∙xClF 3 basing on the chain model of the C 2 F layers. The constructed model explains well the experimentally observed composition of the product of gas-phase fluorination of natural graphite (C 2 F∙0.13ClF 3). Experimental X-ray diffraction patterns of the C 2 F∙xClF 3 compound were studied using the constructed models. Phase composition, crystal structure parameters and sizes of ordered regions were refined. The results show that in the C 2 F∙xClF 3 compound every second or third gap between the C 2 F layers is filled with guest molecules, but ordered regions are nanosized, and an amorphous disordered phase exists as well. Noncovalent bonding interactions between the components of the compound (C 2 F...ClF 3 , C 2 F...C 2 F) were examined using topological analysis of the electron density distribution in the framework of Bader's quantum theory, followed by evaluation of the interaction energies. The calculated characteristics prove that the intercalation of ClF 3 molecules into the C 2 F interlayer space is an energetically favorable process. [Display omitted] • Structural models for crystals of an intercalation compound of F-graphite are built; • The geometry is such that the guest is "locked" between the carbon‑fluorine chains; • Cage-like structure explains long-term stability of the compound with a reactive guest; • Guest–host interactions are of noncovalent nature; • Intercalation of ClF 3 into C 2 F is energetically favorable. [ABSTRACT FROM AUTHOR]

• The CF 0.75 cathode has successfully modified by an ultrathin carbon layer (CF 0.75 @C). • The modified CF 0.75 @C has a high degree of disorganization. • The modified CF 0.75 @C provides additional paths for electronic transmission. • The Li/CF x primary batteries using of CF 0.75 @C cathode achieve better performance. To improve the electrochemical performance of lithium/fluorinated graphite (Li/CF x) primary batteries, the surface of fluorinated graphite cathode is modified with ultrathin carbon layer (CF 0.75 @C) by hydrothermal method. The electrochemical performance and voltage delay of the CF 0.75 @C are significantly improved compared to the pristine CF 0.75 , due to the carbon coating reducing charge transfer resistance and providing more electrons/ions transport paths. As a result, the assembled batteries can discharge at a high rate of 6C and exhibit a specific capacity of 327 mAh/g, corresponding to a high energy density of 625 Wh kg−1. In addition, the optimized batteries exhibit excellent high and low temperature performances (−20 °C ∼ 80 °C), which can be used regularly under harsh conditions. Significantly, this research provides a novel idea to achieve Li/CF x primary batteries with high discharge speed, low voltage delays and a wide temperature range. [ABSTRACT FROM AUTHOR]

In this study, a new composite with layered double hydroxides (LDHs) anchored grown on expanded graphite (EG) interlayers was prepared by vacuum-assisted intercalation and hydrothermal method. Both sides of EG were completely covered by highly dispersed LDHs nanosheets and formed a sandwich-like structure. The unique structure made expanded graphite/layered double hydroxides (EG/LDHs) composites which had excellent F- adsorption performance. The adsorption performance of F- on EG/LDHs was evaluated, and the results indicated that the adsorption process was consistent with the pseudo-second-order kinetic model and the Langmuir model. Pseudo-second-order kinetic model indicated that the adsorption sites were the main factor in the adsorption process. Moreover, the maximum adsorption capacity (Q m) reached 63.21 mg·g-1 at 30 min at room temperature, which was better than most of the same type of adsorbents. The highly dispersed of LDHs anchored growth on EG overcame the disadvantage of aggregation, which exposed more adsorption sites and improved the removal efficiency of F-. In addition, the effects of pH, anion interference, different water quality, and regeneration tests on the EG/LDHs composites were also analyzed, showing that the composites have good stability. [Display omitted] • Highly dispersed LDHs nanosheets anchored growth on expanded graphite nanolayers. • EG/LDHs exhibit efficient adsorption performance on F-. • The efficient removal of F- was attributed to the unique spatial structure and multiple adsorption mechanisms. • EG/LDHs were a low-cost and promising material for F- pollution remediation. [ABSTRACT FROM AUTHOR]

The possibility and consequences of salt-infiltration in graphite must be evaluated for graphite used in molten salt reactors (MSRs) and fluoride-salt-cooled high-temperature reactors (FHRs), which can be subjected to salt pressures as high as 500 kPa. The volume of graphite porosity infiltrated by salt can be measured by direct infiltration and it can be predicted from the graphite pore size distribution, the surface tension of the salt, and the contact angle between the graphite and the salt. While these three properties are believed to be insensitive to irradiation, the former can be impacted by chronic or acute oxidation, and the latter two are highly sensitive to the chemistry of the salt and to events such as air ingress. For MSRs, predictions based on nominal properties of salt and graphite reveal that few graphite grades would satisfy the 4 vol% limit set in the Molten Salt Reactor Experiment, and even fewer would satisfy the 0.5 vol% design target. For FHRs, infiltration limits have not been defined and depend on the effect of infiltration on graphite properties, which are discussed. A hypothesis is presented for properties that may be impacted by infiltration and for which future studies are needed. [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 water-lubricated rubber bearing (WLRB) of ship stern shaft often operates under harsh conditions, which requires a higher tribological performance for bearing materials. Uniformly dispersed nano-fillers can significantly improve the various properties of rubber materials, but nano-fillers are prone to agglomerate in the process of operation, which affects the modification effect. In this paper, a solution blending masterbatch method was used to prepare hydrogenated nitrile rubber (HNBR) nanocomposites and the modification effects of ultra-high molecular weight polyethylene (UHMWPE), nano graphite (NG) powder, nano molybdenum disulfide (NM) and graphite fluoride (GF) on HNBR basic formulation were studied. The results show that the tribological modification of HNBR by UHMWPE is better under low-speed conditions, while the tribological modification of HNBR by GF is better under high-speed conditions. Therefore, in practical engineering application, the reasonable nano fillers are selected for tribological modification according to the operating conditions of water lubricated rubber bearings. It should be pointed out that in order to cover all working conditions, multi nano filler synergistic tribological modification technology is an important technical way to obtain the best comprehensive performance results. • Hydrogenated nitrile rubber is used in water lubricated bearings to solve the problem of friction and wear. • The tribological properties modification of hydrogenated nitrile rubber was studied. • Solution blending masterbatch dispersion process is put forward. • The influence of different nano-fillers and ratios on friction and wear properties have been discussed. [ABSTRACT FROM AUTHOR]

• Nano-Al and fluorographene (FG) were employed as coating agents of boron. • The maximum heat release is 5.6 kJ/g, the minimum ignition delay time is 88 ms. • The B/GF mass ratios is able to tune the ignition and combustion performances. Boron (B) shows great potential applications in the military and aerospace industry due to its high calorific value. However, the reactivity is limited by the inert oxide layer (B 2 O 3) that covers the B particles. Herein, nano-Al, and Fluorographene (FG) are employed as coating materials to enhance the ignition and combustion efficiency of boron. When graphite fluoride (GF) was utilized as an oxidizer (the B/GF mass ratio is 1:9), the maximum heat release of B@nano-Al/GF (∼5.6 kJ/g) and B@FG/GF (∼5.4 kJ/g) were markedly higher than that of raw B/GF (∼2.5 kJ/g), ascribed to the self-activation effect of the coating layer. On this basis, the combustion experiments were performed and their performances were compared and studied. Specifically, the ignition delay time of B@nano-Al/GF and B@FG/GF was decreased to 320 ms 262 ms, respectively, compared with that of raw B/GF (380 ms) with 15 W laser power. This is consistent with the ignition burning test, where the B@6%nano-Al/GF and B@2%FG/GF have higher flame height than raw B/GF. However, the maximum pressure and pressurization rate decreased for B@6%nano-Al/GF and B@2%FG/GF because of the reduced amount of gas caused by decreased boron content. Additionally, the effects of the B/GF mass ratio (1:9, 2:8, 3:7, 4:6) on the combustion performances of composites were fully studied. The pressure output, combustion reaction, and ignition delay time are reduced with B/GF mass ratios increased. This work could provide a general approach to improve the ignition and combustion performance of boron. [ABSTRACT FROM AUTHOR]

The poor electronic conductivity of fluorinated graphite (CF x) is one of the key problems limiting its electrochemical performance. Herein, polydopamine−derived nitrogen−doped carbon coating is adapted to improve the electrochemical performance of CF x by modifying its electronic conductivity. The effects of dopamine hydrochloride/CF x ratio and the carbonization temperature on the electrochemical performance of nitrogen−doped carbon coated CF x samples (CF x @NC−x−y) cathodes are investigated. CF x @NC−x−y cathodes present enhanced rate performance and discharge plateau, and increased energy and power densities, compared with the pristine CF x. Particularly, the CF x @NC−3−350 achieves optimized electrochemical performance, such as a discharge capacity of 550.5 mAh g−1 with a plateau of 2.18 V at 2000 mA g−1, corresponding to high power and energy densities of 4360 W kg−1 and 1171.2 Wh kg−1, whereas the pristine CF x is unable to work. The enhanced electrochemical performance is contributed to the improved electronic conductivity of the nitrogen−doped carbon−coated CF x. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new route for efficient and high-yield production of F-diamane-like nanosheets. • Using expanded graphite allows uniform dispersion of F atoms in the carbon lattice. • The exfoliation of expanded fluorinated graphite can be readily achieved. • Mild sonication produced F-diamane-like nanosheets up to micrometers in size. • Pre-exfoliation/fluorination and sonication is suitable for large-scale preparation. Ultrathin diamond (diamane)-like films or nanosheets have recently been experimentally obtained through chemically induced phase transition (e.g., fluorination) of bilayer graphene films or graphite flakes. To fully exploit the properties of diamane, further advances in the synthesis methods for its large-scale production are required. Herein, we report a new route for the efficient and high-yield production of fluorinated diamane (F-diamane)-like nanosheets. This is achieved by direct fluorination of expandable graphite or thermally expanded graphite with molecular fluorine to form stage-2 graphite fluoride (C 2 F) n made of stacked layers of F-diamane. Subsequently, mild sonication is implemented to exfoliate the layers into F-diamane-like nanosheets of hundreds of nanometers to a few micrometers in lateral size, with a thickness of mostly < 10 nm. [ABSTRACT FROM AUTHOR]

[Display omitted] • New concept of graphene oxide preparation via graphite fluoride hydrolysis. • Well-defined and unambiguous chemical structure of graphene oxide. • Less-defective lattice and higher electrical properties and energy-storage performances. • Efficient and versatile post-functionalization by active hydroxyl reactions. Graphene oxide was universally acknowledged to be a very important precursor to prepare graphene or the relative derivatives, but it was criticized sharply due to its quite inferior electrical properties and many structural defects arising out of strong oxidation process. Non-oxidation synthetic strategy of graphene oxide was expected a good solution to mitigate the disadvantages. Inspired by this concept, we attained a totally new, well-defined graphene oxide, that is , G(C 4)–OH, in which hydroxyl was the unique oxygen-containing group and the hexagonal honeycomb carbon lattice was less-defective, by successfully challenging the hydrolysis of ultra-inert, commercially-available graphite fluoride feedstock. An advantaged structure made G(C 4)–OH greatly outperforming traditional graphene oxide both in fundamental electrical properties, such as conductivity, carrier mobility, and in electrochemical performances when applied in supercapacitors and lithium-ion batteries. As convenient as traditional graphene oxide, G(C 4)–OH was pretty reactive to versatile electrophiles and allowed tremendous post-functionalization opportunities to customize graphene functions and orientate its applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hydration process had been visualized on the fluorinated graphite (FG) layer for the first time. • By building a hydrate formation platform, FG made the hydrate grow upward. • Gas storage rate of FG + SDS system was 20.84 cm3·g−1·min−1, far higher than other materials. • Excellent stability of FG made the performance remain at about 90% after 10 cycles. Achieving rapid and high gas storage is the primary goal of solidified natural gas storage (SNG) using hydrate. In this study, the formation and decomposition process of hydrate were visualized on the fluorinated graphite (FG) layer for the first time by sapphire visible vessel. The results show that, the addition of FG alone can promote the formation of hydrate. After adding fluorinated graphite into SDS system, the gas storage capacity can be further increased to 165.2 cm3 STP/g H 2 O, and the average gas storage rate can be further increased to 20.84 cm3·g−1·min−1, which were 154.7% and 507.7% of SDS system, respectively. Meanwhile, the decomposition speed was faster than SDS system. After optimizing the experimental conditions, it was found that FG-1 with superhydrophobicity could stably exist in the gas–liquid interface and cover it when the dosage reached 1 wt% (13.95 mg·cm−2), and the combination with 300 ppm SDS could greatly promote the growth of hydrate. In addition, the excellent stability of FG made the performance of FG + SDS system remain at about 90% after 10 cycles. The unique growth phenomenon of hydrate in fluorinated graphite system was interesting. By building a hydrate formation platform, FG made water pumped from below to the gas phase and hydrate grow upward continuously. In comparison with other reported carbon nanoparticles, FG system maintained similar gas storage and had excellent gas storage speed, which was 1.35 ∼ 40.67 times faster under similar conditions. Therefore, the reusable FG + SDS system with high gas storage capacity and fast growth rate without induction time and mechanical agitation was a promising alternative to hydrate-based SNG technology. [ABSTRACT FROM AUTHOR]

Fluorinated graphitic layers with good mechanical and chemical stability, polar C–F bonds, and tunable bandgap are attractive for a variety of applications. In this work, we investigated the photolysis of fluorinated graphites with interlayer embedded acetonitrile, which is the simplest representative of the acetonitrile-containing photosensitizing family. The samples were continuously illuminated in situ with high-brightness non-monochromatized synchrotron radiation. Changes in the compositions of the samples were monitored using X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The NEXAFS N K-edge spectra showed that acetonitrile dissociates to form HCN and N2 molecules after exposure to the white beam for 2 s, and the latter molecules completely disappear after exposure for 200 s. The original composition of fluorinated matrices CF0.3 and CF0.5 is changed to CF0.10 and GF0.17, respectively. The highly fluorinated layers lose fluorine atoms together with carbon neighbors, creating atomic vacancies. The edges of vacancies are terminated with the nitrogen atoms and form pyridinic and pyrrolic units. Our in situ studies show that the photolysis products of acetonitrile depend on the photon irradiation duration and composition of the initial CFx matrix. The obtained results evaluate the radiation damage of the acetonitrile-intercalated fluorinated graphites and the opportunities to synthesize nitrogen-doped graphene materials. [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]