Oriented growth of cobalt electrodeposits assisted by an interfacial flow of bubbles

Abstract

High-quality Co products are desirable for a variety of applications due to its unique properties. Herein, an interfacial field of flowing bubbles was used to modify the microstructure of Co deposits in the electrowinning process. The effect of flowing bubbles on morphology, crystallographic structure and impurities of Co deposits were investigated. The nucleation and growth of Co deposits were discussed based on chronoamperometric experiments and sampling experiments. The results indicated that the microstructure of Co deposits was effectively modified by an external field of flowing bubbles. The Co deposits prepared in a quiescent electrolyte were porous and inhomogeneous, while the deposits prepared by using the flowing bubbles were compact and uniform. The nucleation and growth modes of Co deposits were also altered by the flowing bubbles. Preferentially oriented grains in the (110) direction were formed by instantaneous nucleation and screw dislocation growth of the deposits. Improvements in microstructure and crystallographic orientation were able to enhance the purity of Co deposits.