Fern-shaped bismuth dendrites electrodeposited at hydrogen evolution potentials

Abstract

Easy fabrication of nanostructured materials with high porosity and high specific surface area has been drawing much scientific interest. Here, we describe a direct electrodeposition of fern-shaped bismuth dendrites at hydrogen evolution overpotentials without any additive and foreign template. A predeposition step was adopted to adjust and control the nucleation and growth of hydrogen bubbles. Subsequently, the simultaneous electrochemical reductions of Bi³⁺ and H⁺ ions were performed at a constant overpotential. Scanning electron microscopy and transmission electron microscopy characterizations showed that the resultant microporous netlike films consisted of fern-shaped single-crystal bismuth dendrites. The formation mechanism was discussed and ascribed to a “stagnant” template effect of hydrogen bubbles, which limited the lateral growth of fern-shaped dendrites. Such a two-step electrodeposition could also be extended to the nanostructure fabrication of other metals and alloys with high hydrogen overpotentials.