Iron Electrodeposition from Fe(II) Ions Dissolved in a Choline Chloride: Urea Eutectic Mixture

Abstract

In this work, the Fe electrodeposition and nucleation and growth mechanisms onto a glassy carbon electrode from a choline chloride-based deep eutectic solvent (DES) were studied using electrochemical techniques and surface characterization techniques (SEM, EDS, and XPS). The current density transients were characterized by the strong effect of the induction-time during the Fe electrodeposition process. A model comprising 3D nucleation and diffusion-controlled growth that considers the induction-time offset was proposed and validated to analyze and explain the Fe nucleation and growth mechanism on the glassy carbon electrode. Kinetic parameters of Fe nucleation and diffusion-controlled growth such as the nucleation rate, A, the number density of active sites, N0, the diffusion coefficient, D, as well as induction-time were determined. Iron electrodeposit follows an electrochemical aggregative growth mechanism and was constituted by particles of Fe(0) and a mixture of FeO, Fe2O3 and Fe(OH)3.