Synthesis of Intercalation Compounds in the Graphite–HNO3–H3PO4 Systemстатья
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Дата последнего поиска статьи во внешних источниках: 14 сентября 2013 г.
Аннотация:The highly oriented pyrolytic graphite–HNO3–H3PO4 system was studied by x-ray diffraction and potentiometry at different acid concentrations. The results demonstrate that chemical and electrochemical intercalation in the graphite–98% HNO3–85% H3PO4 system yields graphite nitrate, a binary graphite intercalation compound (GIC). H3PO4 is shown to have an ambiguous effect on the concentration ranges of different stages of graphite nitrate, shifting them to lower HNO3 concentrations as compared to the graphite–HNO3–H2O system. In the graphite–98% HNO3–100% H3PO4 system, a stage II ternary GIC is obtained, with an intercalate layer thickness di 14.7 Å. Stages II–VI of this GIC were prepared via exchange reaction between graphite
nitrate and 100% H3PO4. A mechanism for the formation of the ternary GIC is proposed. The synthesis of the cointercalated GIC is likely to involve two steps: in the first step, graphite nitrate is formed; subsequent reaction in the intercalate layer leads to partial replacement of solvated HNO3 by H3PO4 molecules.