Electrode/solution interface adjustment through adding acetamide into the solution for inhibiting hydrogen evolution during iron electrodeposition

Electrodeposited iron films demonstrate commendable attributes such as a high magnetic flux density and enhanced stability. Nevertheless, the occurrence of the hydrogen evolution side reaction during the electrodeposition of iron films significantly increases the internal stress within the films and simultaneously reduces the electrodepositing current efficiency. This study aims to mitigate the hydrogen evolution during electrodeposition of iron by using acetamide (C₂H₅NO) as additive. Electrochemical measurements conducted in this study reveal that the presence of C₂H₅NO molecules in the solution effectively hinders the electrochemical reduction of H⁺ ions, leading to an improvement in the current efficiency for iron electrodeposition, rising from 79 to 87%. Furthermore, analyses using X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) clearly demonstrate that the addition of C₂H₅NO to the electrolyte solution significantly reduces the internal stress of the electrodeposited iron film from 442 to 74 MPa. This reduction, in turn, cause preference a smoother surface, eliminating the occurrence of cracks. Additional insights from Density Functional Theory (DFT) calculations reveal that C₂H₅NO molecules within the solution modify the electrode/solution interface by forming a robust and densely adsorptive layer, primarily composed of C₂H₅NO molecules, on the surface of the iron cathode. Moreover, it is noteworthy that C₂H₅NO molecules exhibit a preference for binding with H⁺ ions over H₂O molecules, thus effectively obstructing the diffusion of H⁺ ions to the electrode surface within the solution.