HOPG AS A HOST FOR REDOX REACTIONS WITH FECL4- IN WATER MEDIUM

An ionic graphite intercalation compound (GIG) with FeCl4- was prepared electrochemically under controlled charge from an FeCl3/HCl solution using highly oriented pyrolytic graphite (HOPG) and a graphitized polyimide him as hosts. From the X-ray diffraction (XRD) 001 lines, the stage of the GIC was determined and the unstable properties of the samples were examined. Gradual transformation of stage-s GIC to stage-(s + 1) GIC confirmed their instability after exposure to air or pumping under vaccum at 120 degrees C. Thermogravimetry analysis of the samples and IR spectra of the gas evolving during GIC drying allowed the quantitative estimation of the co-intercalated species (H2O, HCl) and, hence, the formula of the second-stage GIC was established to be C20-36+FeCl4-, 1.5H(2)O, 0.5HCl. Electrochemical reduction of the second-stage FeCl4--GIC to higher stages and/or Fe-0 particles dispersed on exfoliated graphite was performed in aprotic solution. The influence of co-intercalated molecules on the reduction behaviour of FeCl4--GIC is discussed.