Graphene-MnO2 nanocomposite modified carbon ionic liquid electrode for the sensitive electrochemical detection of rutin

In this paper a carbon ionic liquid electrode (CILE) was fabricated with ionic liquid N-hexylpyridinium hexafluorophosphate, which was further modified by a graphene (GR)-MnO2 nanocomposite to get an electrode denoted as GR-MnO2/CILE. Due to the presence of GR-MnO2 nanocomposite on the electrode surface the electrochemical performances of the modified electrode were greatly enhanced. The fabricated electrode showed strong electrocatalytic ability to the electrochemical reaction of rutin with a pair of well-defined redox peaks appeared. Compared with other modified electrodes, the increase of redox peak currents and the decrease of peak-to-peak separation appeared, which could be attributed to the synergistic effects of the materials used. Electrochemical parameters of rutin on GR-MnO2/CILE were calculated with the electron transfer coefficient as 0.5, the electron transfer number as 1.81, the apparent heterogeneous electron transfer rate constant as 1.61 s−1 and the diffusion coefficient as 1.57 × 10−4 cm2/s. Under the selected conditions the reduction peak current was in linear with rutin concentration from 0.01 to 500.0 μmol/L with the detection limit as 2.73 nmol/L (3σ) by differential pulse voltammetry. The proposed method was further applied to the rutin tablet samples determination with satisfactory results.