Magnetism in graphene oxide nanoplatelets: The role of hydroxyl and epoxy bridges

This work investigates the role of hydroxyl and epoxy bridges in room-temperature ferromagnetism (FM) of pyrolytic graphene oxide nanoplatelets (GOs). Graphene oxide nanoplatelets were synthesized from bamboo pyroligneous acid (BPA), varying oxide coverage (OC) from 5.3% to 13.0%. The amount of hydroxyl and epoxy functional groups in all the GO samples were estimated from results analysis of X-ray photoelectron spectroscopy (XPS). An FM signal was identified, measured at room temperature, which scaled with oxide coverage. Decreased oxide coverage results in enhanced FM. A combination of results from high-resolution transmission electron microscopy (HR-TEM), XPS, energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), electron energy loss spectroscopy (EELS), Fourier transform infrared (FTIR), Raman, and electrical characterization allowed constructing an atomic model for each graphene oxide (GO) structure. First-principles calculations of the atomic model suggest that FM is induced by the adsorption of -OH and -O- atoms on graphene nanoplatelets; therefore, their magnetism is a response to the number of uncompensated spins due to topographic defects. These results suggest future possibilities of the magnetism approach of pyrolytic GO in spintronics of advanced sensors and devices.

Automated summary

This study investigates the role of hydroxyl and epoxy bridges in room-temperature ferromagnetism of pyrolytic graphene oxide nanoplatelets, demonstrating that decreased oxide coverage can enhance ferromagnetism. Various analyses were used to construct atomic models of graphene oxide structures, suggesting potential applications in spintronics for advanced sensors and devices.