Growth mechanism of one dimensional tin nanostructures by electrodeposition

One-dimensional tin nanostructures are synthesized using a template-free facile electrodeposition process without the use of electrolyte additives or surfactants. The needles have an elongated pyramidal shape with a rhomboidal base, and exhibit quasi-dendritic morphologies. The growth of these nanostructures, termed “nanoneedles,” is substrate independent due to the formation of a tin film on the substrate surface prior to nucleation. Tin protrusions form preferentially as localized regions on the surface experience increased mass transport due to the transition from 2D linear to 3D spherical diffusion. Early in the growth, Joule heating melts the protrusion tip, and then spherical diffusion to the liquid tip drives the formation of the needles via self-catalyzed growth. This initial part of the process depends on a critical Nernst diffusion layer thickness (mass transport rate) and is controlled by the variation of solution agitation, tin concentration, temperature, and cathodic current density. Subsequently, deposition is rate limited by the kinetics of tin reduction.