Glassy Carbon Electrode Modified with Au Nanoparticles Electrodeposited from Au(III) Dissolved in a Deep Eutectic Solvent and Its Analytical Performance Towards Dopamine Quantification

Abstract

In this work, the surface of a glassy carbon electrode (GCE) was modified with gold nanoparticles (AuNPs), by potentiostatic electrodeposition, from Au (III) ions dissolved in a deep eutectic solvent formed by choline chloride and urea (reline) at 70 °C. Using electrochemical techniques, both potentiodynamic and potentiostatic, the mechanism and kinetics of the AuNPs nucleation and growth was determined. It was found that the experimental total current density transients jtotal(t) can be adequately describe by a model that Involves adsorption, jad(t), and 3D nucleation and diffusion-controlled growth, j 3D-dc(t),1 see Figure 1a. Furthermore, the modified electrode (GCE/AuNPs) was used in the evaluation of the electrochemical response of dopamine (DA) by means of cyclic voltammetry (CV) and differential pulse voltammetry (PDV) techniques. The results obtained showed that GCE/AuNPs electrode has a greater catalytic activity towards the electrochemical oxidation of DA, with a sensitivity of 129 , see Figure 1b, which is greater than that shown by the bare GCE and comparable to the performance reported for an ITO/AuNPs electrode.2 As well as the presence of a displacement of the oxidation peak towards lower potentials when using the GCE/AuNPs with respect to the bare GCE, which is indicative that GCE/AuNPs requires less energy for the oxidation of DA.