Pattern formation during Sb/Sb2O3 electrodeposition

Sb/Sb2O3 composites are considered promising materials for numerous applications, such as secondary batteries, catalysis and thermoelectrics. Recent research shows that nanostructured Sb/Sb2O3 micro-composites can be obtained straightforward by a single-step electrochemical deposition process. While macroscopically homogenous deposits are obtained in most cases it is shown herein that pattern with Sb and Sb2O3 rich regions emerge under specific conditions. The pattern formation is investigated using electrochemical methods combined with in-situ optical observation and electron microscopy. The origin of pattern formation is proposed to be related to the complex interactions between electrochemical Sb deposition and chemical Sb2O3 precipitation in combination with the emergence of convection patterns in the vicinity of the electrode. These findings contribute to a fundamental understanding in the nascent field of electrochemical metal/oxide co-deposition and can be useful for the rational design of advanced functional composite coatings.