Electrochemical preparation of the graphite bi-intercalation compound with H 2SO 4 and FeCl 3

Abstract

Stage- n FeCl 3-GICs ( n = 2,3) prepared in the standard two-zone method were oxidized galvanostatically in H 2SO 4. The electrode potential vs. electric quantity curves observed during the treatment and the X-ray powder patterns of the products showed clearly the intercalation of H 2SO 4 into FeQ 3-GICs and the formation of the graphite bi-intercalation compounds (GBCs) of FeCl 3 and H 2SO 4. The c axis repeat distance I c of the GBCs, 17.38Å, from the stage-2 FeCl 3-GIC was equal to the sum of those of FeCl 3-GIC, 9.38Å, and of H 2SO 4-GIC, 8.00Å. From the stage-3 FeCl 3-GIC the compound with I c of 25.38Å ( = 9.38Å + 8.00Å + 8.00Å), through the intermediate with I c of 20.73Å ( = 9.38Å + 3.35Å + 8.00Å). The electrochemical reduction of these GBCs suggested that the intercalation of H 2SO 4 into FeCl 3-GICs is reversible.