In situ X-ray diffraction studies of graphite oxidation reaction indicating different exfoliation mechanism than ex site studies

TL;DR

This study uses in situ X-ray diffraction to investigate graphite oxidation, revealing a different exfoliation mechanism than previously observed in ex situ studies, and highlighting the role of acid concentration in weakening graphene interactions.

Contribution

The paper provides new in situ X-ray diffraction data showing that concentrated sulfuric acid does not produce a crystalline graphite oxide phase, challenging prior ex situ findings.

Findings

No strong crystalline order develops in concentrated acid.

Sulfuric acid weakens graphene-graphene interactions.

Concentrated sulfuric acid can disperse graphene with sufficient energy input.

Abstract

We offer a brief overview of the solvent-based graphene production and summarize the current knowledge on the formation mechanism of graphite oxide that proceeds via graphite intercalation compounds. In addition, the results of our in situ X-ray diffraction investigation into this process are presented, discussed and contrasted to the findings by other authors, who employed the same oxidation protocol but examined the samples by ex situ X-ray diffraction. Our results suggest that, contrary to the numerous reports by other authors, no strong crystalline order, unique to graphite intercalation compounds as well as graphite oxide, develops if they remain in concentrated acid. Furthermore, it also appears that, depending on the concentration, sulfuric acid molecules significantly weaken graphene-graphene interactions in graphite. Consequently, concentrated sulfuric acid may be a good solvent for graphene dispersions, if only there is sufficient energy input to separate the layers of graphene.