Introduction of Na in Reduced Graphene Oxide Prepared from Coconut Shells and Its Magnetic Properties

In this article, we report for the first time that the intercalation of sodium (Na) ions into reduced graphene oxide (rGO) sheets can significantly improve its magnetic properties. The intercalation of sodium ions is marked by an increase in the distance between the rGO layers confirmed by X-ray diffraction (XRD) measurements. Unlike pure graphite, the distance between the rGO layers is larger so that it allows sodium ions to stick and intercalate between the rGO sheets. We investigate structure, room-temperature magnetization, and electrical conductivity of Na-intercalated rGO with the variations of rGO:Na mole ratio of 1:0 (rGO), 2:1 (GNa21), 1:1 (GNa11), and 1:2 (GNa12). The sample with the highest Na mole ratio in the series, GNa12, has the highest concentration of defects compared with other samples. GNa12 also has the highest room-temperature magnetization and electrical conductivity. Saturation magnetization (${M}_{S}$) of the samples increases in the same order as the electrical conductivity with increasing Na mole ratio. Our results show that magnetism in Na-intercalated rGO can be explained by a Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction, in which the interaction between the magnetic impurities in rGO is mediated by conduction electrons from the rGO host.