On the cobalt and cobalt oxide electrodeposition from a glyceline deep eutectic solvent

Area of Science:

• Electrochemistry
• Materials Science
• Surface Chemistry

Background:

• Deep eutectic solvents (DES) offer a sustainable alternative for electrochemical applications.
• Understanding cobalt and cobalt oxide electrodeposition is crucial for various technological fields.
• Glycerol-derived DES, like glyceline, present unique properties for metal deposition.

Purpose of the Study:

• To investigate the electrodeposition of cobalt and cobalt oxides from a glyceline deep eutectic solvent.
• To elucidate the nucleation and growth mechanisms of cobalt deposition.
• To determine kinetic parameters and diffusion coefficients of cobalt ions.

Main Methods:

• Cyclic voltammetry and chronoamperometry for electrochemical analysis.
• Scanning electron microscopy (SEM) for surface morphology.
• Raman spectroscopy for material characterization.
• Application of the Scharifker and Hills (SH) theoretical model for transient analysis.

Main Results:

• Metallic cobalt deposition occurs at potentials less negative than the current peak potential.
• Cobalt oxides are formed at more negative potentials.
• Cobalt deposition follows a progressive nucleation and growth mechanism at concentrations >0.05 mol L^-1.
• Instantaneous nucleation is observed at concentrations ≤0.025 mol L^-1 and low overpotentials.
• Kinetic parameters and cobalt ion diffusion coefficient were determined using the SH model.

Conclusions:

• The glyceline deep eutectic solvent is a viable medium for cobalt and cobalt oxide electrodeposition.
• The deposition mechanism is highly dependent on cobalt ion concentration and applied potential.
• The Scharifker and Hills model effectively describes the nucleation and growth processes.