Preparation of corrosion-resistant Ni coating by electrodeposition from ethanol-modified ethylene glycol electrolyte

By modifying ethylene glycol (EG) with ethanol (ET), a highly corrosion-resistant Ni coating was successfully prepared at room temperature. The effects of ET content on the physical properties of ET-modified EG electrolytes, the electrodeposition behavior of Ni(II), and the microstructures as well as corrosion resistance of electrodeposited Ni coatings were investigated. The results reveal that moderate ET addition can reduce viscosity, enhance conductivity, and optimize the coordination environment of Ni(II). Electrochemical measurements indicate that ET addition does not alter the electrochemical reduction mechanism of Ni(II) and the nucleation and growth mode of Ni in the ET-modified EG electrolytes. Ni(II) reduction proceeds via a one-step irreversible reaction, and the nucleation and growth of Ni follow a diffusion-controlled three-dimensional instantaneous nucleation mechanism in the ET-modified EG electrolytes. However, ET addition can regulate some reduction characteristics, such as nucleation overpotential, peak potential, and peak current density, in the ET-modified EG electrolytes. Importantly, ET addition can improve the Ni deposition efficiency and also alter the microstructure of Ni coatings. Surprisingly, electrochemical corrosion tests confirm that incorporating ET into EG can enhance the corrosion resistance of Ni coatings. This work provides a feasible strategy for modifying EG-based electrolytes with ET, and the modified electrolytes have broad application prospects for preparing metal and alloy and modulating their microstructures.