Layer-by-layer assembled ionic-liquid functionalized graphene–polyaniline nanocomposite with enhanced electrochemical sensing properties

In this work, a novel graphene-polyaniline nanocomposite thin film was prepared by the electrostatic layer-by- layer assembly of positively charged graphene sheets functionalized by ionic liquid (IL-GR) and negatively charged sulfonated polyaniline (s-PANI). The use of IL not only enhanced the dispersibility of the graphene sheets, but also provided a positive charge to the graphene thus facilitating the growth of multilayered films. More importantly, it enhanced the electron transport pathway between the graphene sheets and PANI, which is beneficial to the electrocatalytic properties of IL-GR-s-PANI hybrids. Ultraviolet-visible absorption spectrophotometry, Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy and cyclic voltammetry results demonstrated the successful fabrication of the IL-GR-s-PANI hybrid multilayered films. Application of the IL-GR-s-PANI hybrid film in electrochemical sensing was further demonstrated using H2O2 as a model analyte. The ILGR- s-PANI hybrid film was shown to have excellent electrocatalytic activity towards H2O2, resulting in a non-enzymatic H2O2 sensor with a very fast response time (less than 2 s). The proposed IL-GR-s-PANI film based sensor exhibited a wide linear detection range for H2O2 from 0.5 to 2000 mu M with an ultralow detection limit of 0.06 mu M (signal/noise = 3), which outperformed most previously reported H2O2 electrochemical sensors. In addition, good anti-interference and stability were also demonstrated. The IL-GR-s-PANI based sensor was shown to be highly sensitive and selective, fast and stable for the electrochemical sensing of H2O2, which is promising for the development of an enzymeless H2O2 sensor.