Ordered 2D Nanopores in Nickel Electrodeposits–A Self-Organization Phenomenon

Abstract

A new self-organization phenomenon was observed during pulse current electrodeposition of nickel layers from an acidic sulfamate electrolyte containing a few 100 mg/l of a polymeric surfactant. Scanning electron microscopy (SEM) analysis reveals ordered arrays of nanometer sized pits. Within domain of about 1 μm size the pits arrange on a hexagonal lattice with a pore-to-pore spacing of about 120 nm. SEM inspection of cross sections show that the pits are the ends of straight nanochannels of about 40 nm diameter, extending virtually through the complete layer parallel to the growth direction. The additive is an amphiphilic polymer consisting of a backbone carrying carboxylate groups, styrene units and polyether side chains. According to current knowledge the presence of this polymer in the electrolyte and the application of special current pulse patterns are preconditions for the formation of the ordered nanopore arrays. The mechanism responsible for this kind of self-organization is still a matter of speculation but experimental results point to hydrogen nanobubbles acting as templating agents.

Solid‐State Nanopore Array: Manufacturing and Applications

“…They observed a new self‐organization during the electrodeposition and attributed the pore formation mechanism to the hydrogen nanobubble formation and ordering. [ 64 ] Hui et al. reported using nanobubbles as a template, electrochemical fabrication of nanopores in polypyrene (PPy) film.…”

“…Anodic aluminum oxide (AAO) is one of the most popular materials employed for the generation of periodic nanostructures. [ 64 ] It has been used to synthesize aligned nanopore structures because of its flexibly adjustable morphologies, structural stability at high temperature in organic solvents, uniform pore density and distribution which is usually parallel or perpendicular to the surface with cylindrical shape. [ 69 ] Over a decade, AAO nanopore array fabrication has experienced three‐step anodization resulting in disordered structures to two‐step anodization for self‐ordered pore structures, to recent one‐step anodic nanopore array of aluminum oxide, that largely reduces the processing time and increases the ordered nanopore domains.…”

“…They observed a new self-organization during the electrodeposition and attributed the pore formation mechanism to the hydrogen nanobubble formation and ordering. [64] Hui Reproduced with permission. [57] Copyright 2020, Elsevier.…”

“…[ [64][65][66][67] Electrochemical anodization Applicable to nanopores with larger thickness from nanometer scale to micrometer scale. High nanopore density, shape and size are relatively uniform.…”