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

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 j total (t) can be adequately describe by a model that Involves adsorption, j ad (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. References [1] C. Ramírez, E.M. Arce, M. Romero-Romo, M. Palomar-Pardavé. The effect of temperature on the kinetics and mechanism of silver electrodeposition. Solid State Ionics . 169 (2004) 81–85. [2] J. Aldana-González, M. Palomar-Pardavé, S. Corona-Avendaño, M.G. Montes de Oca, M.T. Ramírez-Silva, M. Romero-Romo, Gold nanoparticles modified-ITO electrode for the selective electrochemical quantification of dopamine in the presence of uric and ascorbic acids, Journal of Electroanalytical Chemistry 706 (2013) 69–75 Figure 1