Electrodeposition of nano Ni–Co alloy with (220) preferred orientation from choline chloride-urea: Electrochemical behavior and nucleation mechanism

Highlights: • The electrocrystallization of Ni–Co alloy is 3D-instantaneous nucleation mechanism. • The first time to prepare nano Ni–Co alloys with preferred orientation on (220) crystal planes. • Deposition potential can control the Co content and microstructure of Ni–Co alloy. • Ni–Co alloy coating prepared by potentiostatic has excellent corrosion resistance. -- Abstract: Ionic liquid has become an important new type of solvent, not only with important developments in the field of environmental protection, but also with great potential in the preparation of functional materials. In this work, preparation of nano nickel-cobalt (Ni–Co) alloys with preferred orientation by deposition method in choline chloride-urea (CU) ionic liquid. The results show that metal ions were complexed with Urea in CU. The reduction region of Ni–Co alloy located at −0.6 ∼ −1.2 V. The redox type of Ni–Co alloy in CU solution was irreversible and the nucleation mechanism of Ni–Co alloy was three-dimensional (3D) instantaneous nucleation. By controlling the deposition potential, it can not only effectively change the cobalt content, micro-structure and crystallite size of the Ni–Co alloy, but also influence the preferred orientation of the Ni–Co alloy on the (220) crystal plane. In addition, the Ni–Co alloy has excellent corrosion resistance which was prepared from the CU system.