Synthesis of highly sensitive rGO@CNT@Fe2O3/polypyrrole nanocomposite for the electrochemical detection of Pb2+

Abstract

In this work, highly sensitive nanocomposite materials for the recognition of lead ions in aqueous medium are developed by combining reduced graphene oxide (rGO), carbon nanotubes (CNT) and iron oxide (Fe2O3) drop-casted (as a composite) on a glassy carbon electrode (GCE). This modified electrode was used as a scaffold for polypyrrole (PPy) electrosynthesis, which leaded to the design of a new advanced functional conductive polymeric material (rGO@CNT@Fe2O3/PPy). The physicochemical properties of the composite were probed by X-ray diffraction (XRD), Raman spectroscopy, Fourier-Transform Infra-Red spectroscopy (FTIR) and Scanning Electron Microscopy. The rGO@CNT@Fe2O3/PPy films generated by this strategy exhibited excellent stability and superior conductivity than bare PPy modified surface (without rGO + CNT + Fe2O3 composite). The optimized rGO@CNT@Fe2O3/PPy electrode was applied to the detection of Pb2+ (deposition potential of -1.3 V vs. Ag/AgCl), with peak potential of -0.6 V vs. Ag/AgCl and a higher stripping current peak (1.5 μA/cm2) compared to GCE, rGO@CNT/GCE and rGO@CNT@Fe2O3/GCE. The calibration curve is linear in the range from 0.02 to 0.26 μM (R2 = 0.992), with a sensitivity of 162.8 μA°μM−1 and a detection limit (LOD) of 0.1 nM. Moreover, the modified electrode exhibited low metallic interference, high repeatability and good reproducibility towards the detection of Pb2+. Finally, the usefulness of the nanocomposite was realized by the determination of Pb2+ in tap water.