The Controlling Morphology and Structure of Bismuth Dendrites via Electrodeposition Potential Selection

Electrodeposition of bismuth from an acidic nitrate solution on copper electrodes by use of the potentiostatic mode of electrodeposition has been investigated with the aim to define conditions for obtaining dendritic forms. Morphology and structure of Bi deposits produced at the different cathodic potentials were featured by techniques of scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS) and X-ray diffraction (XRD), and correlated with the polarization features. The Bi dendrites were formed starting from the plateau of the limiting diffusion current density, while granules were formed at the cathodic potential which preceded the plateau. The shape of dendrites changed from very compact, formed at the plateau, to highly branched, formed at cathodic potentials beyond the plateau of the limiting diffusion current density, where the current density continuously grew with the increase in the cathodic potential. Both granules and dendrites showed the forceful preferred orientation in the basal (003) crystal plane with the lowest surface energy. The performed morphological and structural analysis classified Bi into a group of so-called normal metals, characterized by high values of both the exchange current density and overpotential for hydrogen evolution reaction and by low melting points.