Mechanism and kinetics of Gold Nanoparticles Electrodeposited from Au (III) Ions Dissolved in a Deep Eutectic Solvent and Its Analytical Performance Towards Dopamine Quantification

Abstract

The mechanism and kinetics of the electrochemical nucleation and growth of gold nanoparticles (AuNPs) onto a glassy carbon electrode (GCE) from Au(III) dissolved in the reline deep eutectic solvent, DES, at 70ºC, were assessed. From the potentiodynamic technique it was found that gold electrodeposition onto the GCE is a diffusion-controlled process. The potentiostatic current density transients, recorded during the electrodeposition of AuNPs were described by a mechanism where multiple nucleation of 3D gold centers with mass-transfer controlled growth, occurs simultaneously with Au(III) adsorption and the DES residual water reduction on Au nuclei.. From scanning electron microscopy images and energy-dispersive X-ray spectra of the GCE, electrodeposited with gold (GCE/AuNPs), it was found that Au deposit was formed by aggregates, (183 ± 37) nm average size, of AuNPs (of ca 50 nm diameter). The GCE/AuNPs was used for the Dopamine, DA, electrochemical quantification in the presence of uric acid, UA, with the following analytical performance: sensitivity of (32.49 ± 0.37) μA mM-1 and (28.6 ± 0.2) μM detection limit