Effect of (NH4)2SO4 on the co-electrodeposition of Fe-Co alloys

Iron-cobalt alloy is a potential and economical magnetostrictive material, however, our microscopic understanding of the co-electrodeposition process of Fe-Co alloys is still unsatisfactory. In this work, a flat Fe-Co film with 10 μm was successfully prepared by electrodeposition with a non-toxic sulfate solution. The effects of (NH 4 ) 2 SO 4 , an important additive, were studied and DFT calculation was used to analyze the mechanism of (NH 4 ) 2 SO 4 . EIS shows that (NH 4 ) 2 SO 4 can promote the Fe-Co co-deposition process and obviously inhibits the hydrogen evolution reaction. In addition, (NH 4 ) 2 SO 4 can significantly reduce the internal stress of the Fe-Co film by 110,000 MPa, so that the cracks caused by the internal stress are obviously removed. The results of quantum chemistry calculation further show that NH 4 + is more inclined to adsorb on Fe-Co surface than H 2 O and H + , which reduces the hydrogen evolution on the electrode surface. The results are beneficial to improve the Fe-Co co-deposition process, reduce the internal stress and to prepare a high-performance Fe-Co magnetic film. The films will be assembled on the electronic devices with sensors.