Electrochemical oxidation of graphite was performed at high current densities in 47% hydrofluoric acid aqueous solution. Cyclic voltammetry indicated that covalent Csingle bondF bonding formed above 2.4 V vs Pb/PbF2. The sample obtained at higher current densities than 200 mA cm?2 was stage 1 type material with an interlayer spacing of 0.55 nm and it contained a considerable amount of oxygen, together with the covalently bonded fluorine. The discharge profile of this sample as a cathode of lithium primary battery was similar to that of C2.5F prepared under F2 gas atmosphere and the capacity reached 550 mAh g?1. This strongly indicated that not only fluorine but also oxygen in this sample was utilized.

This is a new method  of an OSC synthesis method without hydrofluoric acid. Carbon composite spheres with graphene oxide (GO) walls were synthesized on polymer spheres by a layer-by-layer (LbL) method using polymeric polycation solution and GO colloid solutions. The structural wall thickness of the carbon composite sphere was controlled by the number of LbL cycles. The structural wall thickness was investigated for one to ten LbL cycles. The shape of the carbon composite sphere was uniform, and its surface morphology was similar to that of a  ball. 

65–68% nitric acid and 40% hydrofluoric acid were used. The effects of silicate minerals in starting natural graphite on the preparation and characteristics of reduced graphene oxides (rGOs) have been studied in this work. The study was performed through the measurements of ICP, XRD, FTIR, Raman spectra, UV spectra, AFM and electrochemical performance. The experimental results had shown that the characteristics of the synthesized rGOs, such as layer thickness, defect degree and specific capacitance, etc., were not correlated with silicate minerals assaying in the starting graphite, and no silicate impurities were involved into the rGOs. The mechanism might be attributed to that the silicate minerals were removed from the graphene oxide (GO) in the graphene preparation. This finding suggested that it was not necessary to eliminate deeply silicate minerals from natural graphite before it was used as the starting graphite for the synthesis of graphene with the chemical reduction method, leading to less environmental concerns and lower operation costs.