A novel electrochemical sensor based on thermally reduced graphene oxide for the sensitive determination of dopamine

In this paper, two different reduced graphene oxide samples rGO_H and rGO_M derived, respectively, from the graphene oxide (GO) obtained using traditional and modified Hummers methods were synthesized. Thermal reduction of GO was performed in the presence of malonic acid (MA) and P2O5 additives. The prepared rGO samples were investigated as active electrode materials for the electrochemical determination of dopamine (DA). The structural characterization using XPS demonstrated that the thermal treatment of GO with the mixture of MA and P2O5 leads to incorporation of phosphorus functional groups into the structure of graphene-based material, as evidenced by an increase in the phosphorus content in rGO_H (1.84%) and rGO_M (2.74%). Raman analysis confirms that a slightly larger number of defects are present in the rGO_M sample (I-D/I-G = 0.94) than in the rGO_H structure (I-D/I-G = 0.93). Electrochemical studies using CV and DPV showed that the rGO_M sample significantly improves the oxidation peak current of DA, demonstrating its higher sensitivity to the determination of dopamine than that on rGO_H. Also, it was determined that the proposed sensor based on rGO_M shows a low limit of detection value (0.11 mu M) and high sensitivity (28.64 mu A mu M-1 cm(-2)) toward DA detection.