The formation of tin dendritic nanostructures by electrolysis from the alkaline electrolyte has been investigated. Morphology and structure of Sn dendrites produced applying both potentiostatic and galvanostatic regimes of the electrolysis are characterized by SEM and XRD, respectively. Depending on the applied cathodic potentials, three types of Sn dendrites were obtained: (a) needle-like and spear-like, (b) fern-like, and (c) stem-like dendrites. The very branchy dendrites with branches of the prismatic shape obtained by the galvanostatic regime of electrolysis represented a novel type of Sn dendrites, not previously reported in the literature. To explain the formation of various dendritic forms, correlation with the polarization characteristics for this electrodeposition system is considered. The needle-like and the spear-like dendrites represented monocrystals of (200),(400) preferred orientation, the fern-like dendrites exhibited the predominant (220),(440) preferred orientation, while in the stem-like particles Sn crystallites were oriented to a greater extent in the (440) crystal plane than in other planes. The galvanostatically synthesized Sn particles possessed the strong (200),(400) preferred orientation. The strong influence of parameters and regimes of electrodeposition on structural characteristics of Sn dendrites is explained by the fundamental laws of electrocrystallization taking into consideration the concept of slow-growing and fast-growing crystal planes.

Sn-Pd electrocatalysts with a constant atomic ratio of 60 at.% Sn-40 at.% Pd suitable for potential application in direct ethanol fuel cells were synthesized using a novel two-step electrodeposition method. First, Sn was electrodeposited in various forms of dendrites, from spear-like and needle-like to individual fern-like dendrites to a network of intertwined fern-like dendrites, by varying the cathodic potential and then performing electrodeposition of Pd at a constant current density in the second step. A morphological and elemental analysis of Sn and Sn-Pd electrocatalysts was performed using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) techniques, while the size of Sn dendrites was analyzed using the particle size distribution (PSD) method. Cyclic voltammetry (CV) and chronoamperometry were applied in order to study the catalytic behavior of Sn-Pd electrocatalysts in the ethanol oxidation reaction (EOR), while CO stripping was used to estimate the antipoisoning capability of the electrocatalysts. The Sn surface morphology of the sub-layer was highly correlated with the electrocatalytic activity of the examined Sn-Pd electrocatalysts. The high activity it presented towards the EOR showed the suitability of the Sn-Pd electrocatalyst constructed from individual fern-like Sn dendrites as a sub-layer. Compared to Pd alone, this Sn-Pd catalyst showed more than 3 times higher activity and improved EOR kinetics. This enhancement in the catalytic activity of the Sn-Pd electrocatalysts is attributed to both the morphological characteristics of Sn as a sub-layer and the bifunctional effect.

The correlation between the morphology and crystal structure of zinc dendritic particles produced by electrolysis from the alkaline electrolyte has been established. Morphology and crystal structure of Zn particles electrodeposited by the potentiostatic regime of electrolysis at overpotentials inside (−100 and −160 mV) and outside (−220, −280, and −340 mV) the plateau of the limiting diffusion current density were characterized by scanning electron microscope (SEM) and by X-ray diffraction (XRD), respectively. The particle size distribution (PSD) was performed in order to determine the dependency of the size of dendritic particles on applied electrolysis overpotential. With increasing the overpotential of electrolysis, the shape of particles changed from irregular forms denoted as precursors of dendrites to various forms of dendrites, while the size of the particles simultaneously decreased. All types of Zn dendrites exhibited the strong (002) preferred orientation, while the precursors of dendrites exhibited (101)(002) preferred orientation. The development of strong (002) preferred orientation was explained and discussed by making an analogy with the electrolytic production of lead dendrites from the concentrated nitrate electrolyte. Although zinc and lead belong to different types of crystal lattice (Pb-face-centered cubic type and Zn-hexagonal close-packed type), they have a common characteristic that is manifested by the strong preferred orientation in the crystal plane with the lowest surface energy.