A systematic study of electrolyte effect on exfoliation efficiency and green synthesis of graphene oxide

Abstract A systematic study on the effect of the electrochemical exfoliation of graphite was conducted to provide new insights on the structure and material properties. Graphene-like structures are produced at scale currently using the wet chemical approaches, which is usually followed by an additional reduction step. The electrochemical exfoliation constitutes a promising alternative method for green, fast, and safe industrial exploitation, due to its low cost, mild conditions, basic equipment requirement and eco-friendlier electrolytes. Additionally, crystal structure of graphene related materials demonstrates less defective sights due to the high speed of exfoliation. A thorough investigation was conducted on critical parameters of the electrochemical process. The parameters of concentration, voltage, temperature and sonication assistance were studied using the randomized block design approach for various electrolytes. After the evaluation and screening of the materials with several characterization techniques, three optimization routes were selected, which included a modified Hummers' method, exfoliation based on the surface energy of pure DMF, and violent pH neutralization. The production of graphene oxide nanoplatelets was achieved, with high oxidation rates, high crystallinity and limited imperfections. The materials were consisted of less than 10 layers and up to 5 layers as demonstrated by the low crystallite size, which was also demonstrated for GO that underwent post-treatment optimization. Higher yields were achieved with electrolytes known for their strong oxidative effect, while the hydrogen peroxide electrolyte and the ionic liquid demonstrated lower exfoliation rates.