Electrochemical behavior of graphite in electrolyte of sulfuric and acetic acid Original Research Article

Electrochemical formation of graphite intercalation compounds (GICs) has been studied in the electrolyte with mixed sulfuric acid and acetic acid. The results show that, with addition of acetic acid, GICs can be synthesized in the electrolyte with sulfuric acid concentration as low as 3.6M, even though no GIC is formed in pure acetic acid. The stage structure of the synthesized GICs varies with the concentration of sulfuric acid, and stage 3 can be obtained in the electrolyte with 3.6M of sulfuric acid. The onset potential and current efficiency for intercalation changes linearly from 0.54 to 1.10 V (versus Hg/Hg2SO4) and from 0.90 to 0.68, respectively, with acetic acid addition. Two paths of graphite oxidation in an electrochemical reaction have been observed. Commonly the graphite oxide (GO) is formed via a stage 1 GIC, however, GO can be formed via a stage 2 GIC directly at elevated temperature when acetic acid is added in the electrolyte. The reduction of sulfur content in the GIC and efficiency of GIC synthesis might be balanced with an appropriate combination of sulfuric acid and acetic acid.