Investigation of physical properties of Fe_2O_3 and graphene-based sandwich-type electrodes for biosensor technology

摘要

The usage of composite materials in which graphene combined with magnetic nanoparticles offers benefits for biomedical applications. Stabilization of nanoparticles on the electrode surface which is necessary for biosensors and other applications is still an important issue to be solved. Here the stabilization of the nanoparticles is achieved by inserting nanoparticles between two graphene layers in a sandwich structure. Furthermore, it has been theoretically predicted that sandwich-type structures prepared with metal nanoparticles between two graphene layers would have extraordinary physical properties. In this study, Fe_2O_3/SLG (single-layer graphene) and the sandwich-type SLG/ Fe_2O_3/SLG electrodes were produced. Fe_2O_3 nanoparticles were synthesized by the sol-gel method, and graphene was produced by CVD (chemical vapor deposition) on Cu foil and then transferred onto FTO (fluorine-doped tin oxide). Fe_2O_3/SLG composite structure was produced by the drop-casting process. The structural, magnetic, and electrochemical properties of samples were investigated in detail. Structural analysis revealed that Fe_2O_3 has an α-phase with a rhombohedral crystal structure and the mean particle diameter is 128 nm. Raman and SEM analysis also confirmed the quality of SLG and the sandwich-type graphene structure. The nanoparticles have a magnetic phase transition which has Morin temperature at about T - 263 K. Also, Fe_2O_3 nanoparticles have shown ferromagnetic behavior at room temperature with 0.16 Am~2/kg remanent magnetization and 0.203 T coercive field. This work demonstrates the effectiveness of graphene sandwich-type electrodes to eliminate the main stabilization obstacle of magnetic nanoparticles especially for biosensor applications.