Transformation of randomly aggregated gold nanoparticles into dendritic structures by square wave potential pulses

Dendritic gold was facilely fabricated here via a simple two-step method by treating a pure gold electrode sequentially in two blank solutions for very short periods of time. The electrode surface was firstly roughened in 2 M HCl by a step potential for 50 s to form a three-dimensional (3D) nanoporous film consisting of randomly aggregated gold nanoparticles, and was then treated with square wave potential pulses for 500 s in 2 M H2SO4 to fulfill the transformation of the aggregated nanoparticles into dendritic structures. The influence of potential range, square wave frequency, electrolyte, and potential waves on the dendrite formation was investigated. A one-step method was also explored for mechanism comparison by treating the polished gold instead in the presence or absence of HAuCl4.