Anodic oxidation of graphite in 10 to 98% HNO3

Systematic studies into the anodic oxidation of natural fine-particle graphite in 10 to 98% HNO3 are described. The concentration ranges of the formation of stage I-IV graphite nitrates are determined. Below C-HNO3 = 55%, no graphite intercalation compounds are detected by x-ray diffraction. The electrochemical oxidation of graphite in dilute HNO3 yields graphite oxide phases. Their formation seems to be preceded by intercalation and hydrolysis, which occur in parallel. The properties of the oxidation and hydrolysis products are shown to depend strongly on the process parameters.