The role of interface concentration gradient in the formation of silver dendritic particles

Dendritic structures are widely present in nature, from river networks to snowflakes. There is a long-term interest in discovering their common formation mechanism, especially the driving force leading to the branching and the reason to keep symmetry. The inhibition of lithium dendrites in secondary batteries also calls for the deep understanding on the formation of dendritic structures. Here in this article, we report an investigation on the driving force of the formation of dendritic structures. Silver particles are synthesized by Galvanic replacement reaction (GRR) in which metal rods are immersed into the silver nitrate solution to reduce silver ions followed by silver particles formation on the surface of rods. The silver ions concentration profile near the rods is measured by Mach-Zehnder interferometer during the reaction. It is found that the formation of silver dendritic particles is accompanied by the interface concentration gradient. A regulation on the gradient leads to the change of silver morphology, experimentally confirming the dominant role of the interface concentration gradient in the formation of diverse structures.