In-situ electrochemically deposited Fe3O4 nanoparticles onto graphene nanosheets as amperometric amplifier for electrochemical biosensing applications

[Display omitted] •A new and novel in-situ electrochemical process for incorporating iron oxide nanoparticles onto CVD few-layered graphene nanosheets.•Fast electron transfer and high conductivity (20-times higher compared to pristine graphene).•Good sensing performance with detection limits of 4.4, 8.2 and 8.35 uM for H2O2, glucose and acetylcholine, respectively. A novel in-situ approach based on electrochemical techniques has been developed for incorporating iron oxide nanoparticles onto CVD-grown few-layered graphene nanosheets. The embedment of Fe3O4 nanoparticles within graphitic planes was realized by sweeping conductive Gr electrode in a diluted solution of ultrafast redox probe K3[Fe(CN)]6. The morphology and chemical composition of the modified graphene sheets were probed by Scanning Electron Microscopy and Energy Dispersive X-ray analysis, respectively. X-ray photoelectron spectroscopy technique was also employed to provide deeper insights on material structure. Electrochemical behavior of the material was then examined by Cyclic Voltammetry and Electrochemical Impedance Spectroscopy. The results clearly revealed that graphene sheets were evenly decorated by Fe3O4 particles with relatively uniform size of less than 50 nm. The presence of such ‘ceramic’ particles has provided active sites for promoting electron transfer from redox-active species in the solution. Meanwhile, the electrochemical reduction of imperfect graphene sheets has greatly restricted the oxygen moieties, thus improving the conductivity of the material. As a consequence, an increase in amperometric current response of at least 20-fold was recorded after the graphene sheets were electrochemically tailored with iron-based nanoparticles. The graphene-Fe3O4 nanocomposites were then applied for sensing H2O2 (non-enzymatic), glucose and acetylthiocholine (enzymatic). The developed sensors had excellent performances with detection limits of 4.4, 8.2 and 8.35 μM for H2O2, glucose and acetylthiocholine, respectively.