Electrochemical nucleation and growth of aluminum nanoparticles and leaf-like flat microstructures from reline deep eutectic solvent: Effect of temperature and angular speed of working electrode

Abstract

The main objective of this work was to use reline deep eutectic solvent, containing Al(III) ions, for the electrochemical study of the nucleation and growth of aluminum onto a glassy carbon electrode at different temperatures and angular speeds (ω) of the working electrode. In order to fulfill this, electrochemical and surface characterization techniques were used. It was found that as temperature increased, the onset of the Al(III)DES reduction occurred at less negative potentials while the current peak of the voltammograms increased. These indicate that Al deposition thermodynamics and kinetics were favored. Practically, no anodic current was detected due to Al passivation by Al(OH)3(s) and γ-Al2O3(s). At ω=0 r/min, the Al deposition chronoamperograms were analyzed by a theoretical model comprising Al 3D diffusion-controlled nucleation and growth and residual water reduction. However, those recorded at different angular speeds were analyzed with a theoretical model where adsorption−desorption and diffusion-controlled nucleation−growth occurred simultaneously. The deposits were characterized by SEM, EDX, XPS and XRD. At ω=0 r/min, formation of well distributed nanoparticles ((78.1±9.5) nm) was observed, while at ω=900 r/min the deposit was formed by multiple 10 μm diameter leaf-like flat microstructures, composed by Al, Al(OH)3(s) and γ-A2O3(s).