Electrochemical study of the graphite-HNO3 systemстатья
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Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:The anodic oxidation of highly oriented pyrolytic graphite in 50 to 98% HNO3 was studied in a galvanostatic mode at a current of 1.5 mA. At HNO3 concentrations from 55 to 98%, the potential-vs.-charge curves showed steplike behavior, and the number of steps increased with decreasing acid concentration, reflecting the successive formation of stage III, II, and I graphite nitrate. Electrochemical synthesis of stage I graphite nitrate was shown to be possible in 75 to 98% HNO3. The anodic oxidation in 60 to 70% HNO3 resulted in a stage I + II mixture, and that in 55% HNO3 yielded a mixture of stage II and a defect graphite phase. In 50% HNO3, no intercalation compounds were formed. The specific charge required for the formation of stage I graphite nitrate was determined as a function of HNO3 concentration. The assumption is made that, in dilute HNO3 solution containing significant amounts of water, rapid electrochemical oxidation leads to the formation of graphite oxides.