Application of Multi‐walled Carbon Nanotube Modified Carbon Ionic Liquid Electrode for the Voltammetric Detection of Dopamine

Abstract

AbstractIn this paper a carbon ionic liquid electrode (CILE) was fabricated by using ionic liquid 1‐butyl‐3‐methylimidazolium hexafluorophosphate (BMIMPF6) as the binder. Then a Nafion and multi‐walled carbon nanotubes (MWCNTs) composite material was further cast on the CILE surface to get a modified electrode denoted as Nafion‐MWCNTs/CILE. The fabricated electrode showed strong electrocatalytic ability to the oxidation of dopamine (DA) with a pair of well‐defined redox peaks appeared. Compared with other electrodes the redox peak currents increased with the decrease of the peak‐to‐peak separation (Δ Ep), and the result was attributed to the specific properties of MWCNTs and its interaction with imidazolium ion present on the CILE surface. The electrochemical parameters of DA on the Nafion‐MWCNTs/CILE were calculated with the electron transfer coefficient (α) as 0.433, the electron transfer number (n) as 1.1, the apparent heterogeneous electron transfer rate constant (ks) as 0.774 s−1 and the diffusion coefficient (D) as 3.05 × 10−5 cm2/s. Under the selected conditions the oxidation peak current was in linear with DA concentration from 1.0 × 10−5 to 6.0 × 10−4 mol/L with the detection limit as 6.75 × 10−6 mol/L (3σ)by differential pulse voltammetry. The proposed method showed good selectivity and was further applied to the DA injection samples determination with satisfactory results.