Toward graphene chloride: chlorination of graphene and graphene oxide

Halogenated graphene derivatives are interesting due to their outstanding physical and chemical properties. In this paper, we present various methods for the synthesis of chlorinated graphene derivatives from graphene oxide and thermally reduced graphene. We performed exfoliation of graphene oxide in a chlorine atmosphere, plasma assisted exfoliation of graphite oxide using microwave radiation and finally direct chlorination of thermally reduced graphene by liquid chlorine under deep UV irradiation. The influence of the chlorination method on the resulting chlorinated graphenes was investigated by characterization of the graphenes, which was carried out using various techniques, including SEM, SEM-EDS, high-resolution XPS, FTIR, STA and Raman spectroscopy. Electrochemical properties were investigated by cyclic voltammetry. Although the graphenes were structurally similar, they involved remarkably different chlorine concentrations. The most highly chlorinated graphene exhibits a chlorine concentration of 11.7 at%. Chlorinated graphenes with such properties could be used for reversible chlorine storage or as a starting material for further chemical modifications. Chlorinated graphene derivates with chlorine concentration exceeding 11 at% were synthesized by high temperature exfoliation in chlorine atmosphere. Halogen graphenes have a great potential for electronic and electrochemical devices.