Electrochemical Behavior and Electrodeposition of Fe-Co-Ni Thin Films In Choline Chloride/Urea Deep Eutectic Solvent

Fe-Co-Ni coating, a vital type of transition metal alloy, shows great potential in the field of hydrogen storage and magnetic materials. In this study, Fe-Co-Ni coatings were prepared on Cu substrates from a deep eutectic solution of choline chloride/2Urea (ChCl/2Urea) DES by electrodeposition. The effects of deposition potential on the morphology, chemical composition, crystal structure, corrosion resistance and magnetic properties of nanostructured Fe-Co-Ni coatings were explored by scanning electron microscopy (SEM-EDS), X-ray diffraction (XRD), potentiodynamic polarisation and vibrating sample magnetometer (VSM). The results revealed that the reduction process of Fe-Co-Ni alloy in ChCl/2Urea DES was irreversible, which was controlled by diffusion. The nucleation of Fe-Co-Ni on the Cu electrode in ChCl/2urea DES was three-dimensional instantaneous nucleation demonstrated by CA result. SEM results indicated that the surface morphology, microstructure, compose and crystallite size of the Fe-Ni-Co alloy were related to the deposition potential. XRD results showed that the Fe-Co-Ni coatings were composed of face-centered cube (fcc, NiFe) and body-centered cube crystals (bcc, FeCo). The Fe-Co-Ni coatings prepared from ChCl/2urea DES at different deposition potentials showed good corrosion resistance. In addition, potential-dependent magnetic properties of the system characterized by VMS demonstrated that magnetic anisotropy for Fe-Co-Ni coatings was obvious