Distribution of intercalates in CrO3H2SO4-graphite and CrO3HClO4-graphite bi-intercalation compounds

Binary graphite intercalation compounds with sulfuric acid (H2SO4GICs), perchloric acid (HClO4GICs) as well as chromium trioxide (CrO3GICs) are known to be readily de-intercalated due to cathodic reduction and/or washing with aqueous solutions. The subsequent electrochemical intercalation of sulfuric and perchloric acid into the host CrO3GICs has resulted in the ternary CrO3H2SO4GICs and CrO3HClO4GICs, respectively. The products of the subsequent intercalation composed of the bi- and co-intercalation domains appeared to be very resistant to de-intercalation. The comparison of the results of the X-ray microprobe and X-ray diffraction analysis obtained for the original CrO3GICs and the cathodically reduced ternary compounds have allowed insight into the structural and chemical changes developing during the subsequent intercalation/de-intercalation process. The knowledge of these properties is helpful for both the better understanding of the intercalation mechanism of the acids into the host CrO3GIC and the elucidation of the extremely high stability of the ternary compounds.