Synthesis and physicochemical properties of intercalation compounds in thegraphite-HNO3 system

Intercalation of nitric acid (58-98%) into highly oriented pyrolytic graphi te was studied by x-ray diffraction and potentiometry. The lowest HNO3 conc entrations at which chemical and electrochemical intercalation reactions oc cur were determined. The phase composition of chemical intercalation produc ts was found to correlate with the HNO3 concentration. Chemical intercalati on was studied by potentiometry at HNO3 concentrations of 80 to 98%. The po tential of graphite nitrate was measured as a function of time. The potenti al of the graphite intercalation compound with the highest degree of interc alation was found to be determined by the redox potential of the acid. Anod ic oxidation of graphite was performed in 58 to 75% HNO3. At a constant cur rent, the potential-vs.-charge curves show well-defined steps. Over the ent ire range of HNO3 concentrations examined, the anodic oxidation of graphite yields stage II graphite nitrate.