Explore the vast range of titles available.

In this work, graphite intercalation compounds (GICs) were synthesized using three different oxidizers: (NH4)2S2O8, K2S2O8, and CrO3 with and without P2O5 as a water-binding agent. Furthermore, the samples obtained were heat-treated at 800 °C. Specimens were characterized by optical microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), and scanning electron microscopy (SEM). The correlation between different characteristic parameters of the Raman analysis has shown that the use of CrO3 results in a much higher structural disorder compared to the products obtained using persulfate oxidizers. Narrowing the correlation set revealed that minimal defect concentration can be reached by using K2S2O8, while the use of (NH4)2S2O8 causes a slightly higher concentration of defects. It was also established that the additional use of P2O5 can help to achieve more effective intercalation and has a positive effect on the formation of the stage I GIC phase. After heat treatment, the intercalated products mostly return to a graphite-like structure; however, the samples obtained with CrO3 stand out with the most significant changes in their surface morphology. Therefore, analysis suggests that GICs obtained using persulfate oxidizers and P2O5 could be a candidate to produce high-quality graphene or graphene oxide.

The carbon gel and carbon gel doped with 0.5, 1 and 2 wt% of graphite intercalation compound were used for the removal of heavy metals from aqueous solutions. These materials were prepared by a sol-gel process that involves a polycondensation of resorcinol and formaldehyde. Nitrogen adsorption, scanning electron microscopy, energy dispersive spectroscopy and fourier transform infrared spectroscopy were used for a morpho-structural adsorbent investigation. In the present paper, Cu, Co, Pb and Ni ions adsorption experiments were carried out in batch conditions under magnetic stirring. The effect of some parameters such as contact time, metal ions’ concentration and pH were examined. Adsorption data on all sorbents, followed both the Frendlich and Langmuir models. The data better fitted the Langmuir isotherm than the Frendlich one. The highest degree of removal was achieved for Pb ions at the initial concentration of 10 mg/l and for 2 g/l adsorbent dose. Adsorption results expressed as adsorption capacities showed that carbon gel doped with 2 wt% of graphite intercalation compound is the best adsorbent. Graphical Abstract

Exfoliated graphite (EG) is a promising macroporous sorbent for oils and liquid hydrocarbons on water surfaces. The preparation of EG includes a synthesis of graphite intercalation compounds, expandable graphite and its thermal exfoliation. The structure of the initial graphite intercalation compound (GIC) has a significant influence on the structure of exfoliated graphite and its sorption properties: sorption capacity and selectivity of water/octane sorption. Thus, the aim of this work was to investigate the relationship between the structure of EG based on 1st stage, 2nd stage, 3rd stage, 4th stage GICs and EG sorption properties and water wettability. The influence of the GIC stage number on the EG sorption and surface properties is studied. EG obtained from 1st stage GIC at 1000 °C is characterized by a higher sorption capacity toward octane than EG from 4th stage GIC. The selectivity of octane/water sorption reduces when decreasing the GIC stage number from 4 to 1. The high sorption of water can be explained by a higher surface area of EG and the presence of remaining oxygen groups on the edges of graphite crystallites in the EG structure. The EG structure was investigated by XRD, SEM, nitrogen adsorption–desorption method, FTIR and Raman spectroscopy.

Different chemical formulations for the synthesis of highly intercalated graphite bisulfate have been tested. In particular, nitric acid, potassium nitrate, potassium dichromate, potassium permanganate, sodium periodate, sodium chlorate, and hydrogen peroxide have been used in this synthesis scheme as the auxiliary reagent (oxidizing agent). In order to evaluate the presence of delamination, and pre-expansion phenomena, and the achieved intercalation degree in the prepared samples, the obtained graphite intercalation compounds have been characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray powder diffraction (XRD), infrared spectroscopy (FT-IR), micro-Raman spectroscopy ( μ -RS), and thermal analysis (TGA). Delamination and pre-expansion phenomena were observed only for nitric acid, sodium chlorate, and hydrogen peroxide, while the presence of strong oxidizers (KMnO 4 , K 2 Cr 2 O 7 ) led to stable graphite intercalation compounds. The largest content of intercalated bisulfate is achieved in the intercalated compounds obtained from NaIO 4 and NaClO 3 .

FeCl 3 -intercalated graphite intercalation compounds (GICs) with high reversible capacity and high volumetric energy density are attractive anode material alternatives of commercial graphite. However, the rapid capacity decay, which was induced by chloride dissolution and shuttling issues, hindered their practical application. To address this problem, here, we introduce flake-like Fe 2 O 3 species with inherently polar surface on the edge of FeCl 3 -intercalated GICs through microwave-assisted transformation of a fraction of FeCl 3 component. Theoretical simulations and physical/electrochemical studies demonstrate that the introduced Fe 2 O 3 component can afford sufficient polar active sites for chemically bonding the soluble FeCl 3 and LiCl species based on the polar—polar interaction mechanism, further inhibiting the outward diffusion of the chlorides and immobilizing them within the GIC material. In a lithium ion cell, the FeCl 3 -intercalated GIC with a suitable Fe 2 O 3 content shows remarkably improved cycling stability with a high reversible capacity of 1,041 mAh·g −1 at a current density of 200 mA·g −1 . Capacity retention of 91% is achieved at a high current density of 1,000 mA·g −1 over 300 cycles. This work opens up the new prospect for immobilizing chlorides by introducing inorganic species in GIC for long-cycle electrochemical batteries.

The superconducting transition temperature, Tc, of the graphite intercalation compound, CaC6, was calculated using the Roeser–Huber (RH) formalism. This method was adapted to alloys with complex crystal structures by identifying symmetric paths for the superconducting charge carriers (Cooper pairs) and incorporating interactions with neighboring atoms through phonon coupling. The evaluation of the lowest energy levels, Δ(0), along all relevant crystallographic directions reveals a slight anisotropy between the in-plane and out-of-plane directions, consistent with the experimental observation of the gap anisotropy by point contact spectroscopy. The Tc values obtained for CaC6, CaC6 with applied high pressure, and YbC6 show good agreement with experimental data, thereby supporting both the validity of the RH approach and its predictive capability in describing superconductivity within complex crystal structures.

In present work, we describe the synthesis of graphite intercalation compounds with perrhenic acid (HReO4-GIC) through the anodic oxidation of graphite in aqueous perrhenic acid solution and their thermal exfoliation. Due to electrochemical treatment of graphite in perrhenic acid solution, ReO4− ions are intercalated into interlayer spaces of graphite. Anodic oxidation of graphite in HReO4 solution leads to the formation of 3-stage GIC. Simultaneously, some amount of perrhenic acid becomes deposited on the graphite surface and edges. In the next step, thermal treatment of the previously synthesized GIC was performed, causing both the exfoliation of graphitic structure and transformation of perrhenic acid into rhenium oxides on the surface of graphene layers. The yielded product was exfoliated graphite-ReO2/ReO3 composite. The obtained composite was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Raman spectroscopy. Additionally, specific surface area of the exfoliated materials was measured.

Graphene-polypyrrole (GP) nanocomposites were synthesized by a wet-way protocol using a graphite bisulfate (GBS) precursor. Consequently, GBS, a type of graphite intercalation compound, was prepared in the presence of concentrated sulfuric acid in the presence of a potassium periodate oxidizer. Three different types of graphite precursor with particle sizes of <50 μm, ≥150, ≤830 μm, and ≤2000 μm were used for this purpose. It was found that in the Raman spectra of GBS samples, the characteristic D band, which is caused by defects in the graphene layer, disappears. Therefore, the proposed synthesis protocol of GBS could be considered as a prospective intermediate stage in the preparation of graphene with low defect concentration. In contrast to alkali metal intercalation, the intercalation process involving anions with a relatively complex structure (e.g., HSO4−), which has been much less studied and requires further research. On the basis of the results obtained, structural models of graphite intercalation compounds as well as GP nanocomposites were discussed. The most relevant areas of application for GP nanocomposites, including energy storage and (bio)sensing, were considered. This work contributes to the development of cost-effective, scalable, and highly efficient intercalation methods, which still remain a significant challenge.

The typical metal chloride‐graphite intercalation compounds (MC‐GICs) inherit intercalation capacity, high charge conductivity, and high tap density from graphite, and these are considered as one of the promising alternatives of graphite anode in rechargeable metal‐ion batteries (MIBs). Notably, the special interlayer decoupling effects and the introduction of extra conversion capacity by metal chloride could greatly break the capacity limitation of graphite anodes and achieve higher energy density in MIBs. The optimization of both graphite host and metal chloride species with specific structures endows MC‐GICs with design feasibility for different application requirements of different MIBs, such as several times the actual capacity compared to graphite anodes, rapid migration of large carriers, and other properties. Herein, a brief review has been provided with the latest understanding of conductivity characteristics and energy storage mechanisms of MC‐GICs and their interesting performance features of full potential application in rechargeable MIBs. Based on the existing research of MC‐GICs, necessary improvements and prospects in the near future have been put forward. Metal chloride‐graphite intercalation compounds are recognized as promising alternative electrode materials of graphite. It presents unique electronic characteristics and allows more metal‐ion storage with several energy storage mechanisms. Based on the designing of the graphite host, intercalator, and electrode structure, metal chloride‐graphite intercalation compounds delivered high capacity, fast electrochemical kinetics, and superior cycling stability for rechargeable metal‐ion batteries.

We use first-principles calculations within the density functional theory (DFT) to explore the electronic properties of stage-1 Li- and Li+-graphite-intercalation compounds (GIC) for different concentrations of LiCx/Li+Cx, with x = 6, 12, 18, 24, 32 and 36. The essential properties, e.g., geometric structures, band structures and spatial charge distributions are determined by the hybridization of the orbitals, the main focus of our work. The band structures/density of states/spatial charge distributions display that Li-GIC shows a blue shift of Fermi energy just like metals, but Li+-GIC still remains as in the original graphite or exhibits so-called semi-metallic properties, possessing the same densities of free electrons and holes. According to these properties, we find that there exist weak but significant van der Waals interactions between interlayers of graphite, and 2s-2pz hybridization between Li and C. There scarcely exist strong interactions between Li+-C. The dominant interaction between the Li and C is 2s-2pz orbital-orbital coupling; the orbital-orbital coupling is not significant in the Li+ and C cases, but dipole-diploe coupling is.