Crystallization behavior and formation mechanism of dendrite Cu2O crystals

Abstract

The crystal growth behavior of dendrite-like Cu₂O crystals during galvanostatic electrodeposition was investigated. The deposited Cu₂O particles are single-phase cuprites and their morphologies change from octahedral in a static electrolyte to dendrites in a stirred electrolyte. The morphology evolution is attributed to the enhancement of the transfer of Cu²⁺ and the break in the Cu²⁺ depletion zone around the nuclei, which promotes the deposition of Cu²⁺ ions along the <110> directions to form a face-centered cubic (FCC) Cu lattice under a cathodic potential. Meanwhile, O atoms diffuse into the Cu lattice to form a cuprite Cu₂O lattice with a corresponding lattice expansion. Consequently, the morphology of the Cu₂O crystals develops into dendrites and the growth direction of the dendritic branches are all along the <110> directions. Furthermore, the conduction type of Cu₂O was also changed from p-type to n-type when the morphology of the Cu₂O crystals varied from octahedral to dendrites. The mechanism of the morphology evolution in the present reaction system is helpful for controlling the morphology of the Cu₂O crystals.