Reduction of Graphene Oxide Via Plasma Immersion Ion Implantation

Graphene oxide sheets were irradiated with argon and hydrogen plasma in the configuration of plasma immersion ion implantation with a pulsed negative voltage of -5 kV at varying time intervals, ranging from 2 to 8 min. Their characteristics were investigated in terms of surface and structural modification, elemental compositions and bonding, and sheet resistance. The irradiation removed surface irregularities and transformed it into a smoother surface. Raman spectroscopy analysis revealed that the sp2 network was restored after the radiation. Due to different energy loss mechanisms, hydrogen irradiation resulted in a smaller size of sp2 domains, while argon radiation led to more structural defects. The XPS results showed that a significant amount of hydroxyl/epoxy groups were removed, and an increase in carboxyl groups was observed after the irradiation. This indicates that some surface reactions, such as hydrogenation and adsorption of molecules from the environment, occurred. Conductive graphene oxide sheets were obtained as the sheet resistance of the irradiated graphene oxide was reduced compared to that of the pristine graphene oxide. This demonstrates that PIII could be a potential technique to reduce graphene oxide.