A detailed computational exploration and experimental surface/electrochemical analyses of mild steel functionalized by zinc-aminotris methylene phosphonic acid complex film

In the present integrated experimental/theoretical work, the synergistic inhibition effects of aminotris methylene phosphonic acid (ATMP) and Zn ions for steel corrosion mitigation in NaCl solution were examined. The inhibition property of ATMP:Zn mixture was evaluated by electrochemical approaches including potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS). In addition, the chelation between ATMP-zinc ions and/or iron cations was investigated applying various morphological approaches. The ATMP and ATMP-Zn complex chemical structures were identified via UV-Vis and FT-IR spectra. According to EIS outcomes, the excellent inhibition efficiency of about 99% was achieved within 72 h steel subjection to 3.5% NaCl media containing 200:600 ppm ATMP:Zn mixture. The PDP plots disclosed that the complex inhibitors mainly retarded the steel corrosion cathodically. Furthermore, FE-SEM and AFM microstructures analyses clarified the emergence of a high-coverage ATMP:Zn complex inhibitive layer over metallic adsorbent, evidencing significant corrosion mitigation. The detailed results elucidated from EDS and XPS spectra ensured the successive chemical bonding of ATMP molecules with zinc and/or iron ions. Alongside experiments, fundamental theoretical studies at detailed microscopic levels (i.e., atomic and electronic) were conducted using molecular simulations and quantum mechanics (QM). Monte Carlo (MC) combined with molecular dynamics (MD) was applied for assessing the organic-inorganic inhibitor adsorption features. Additionally, electronicstructure QM calculation on the basis of density functional theory (DFT) was adopted so as to fundamentally analyze the reactive sites determining the inhibitor adsorption. The outcomes elucidated by MC/MD tools ensured the surface adsorption propensity of hybrid inhibitors. The DFT based observations proposed that the inhibitors adsorption likely occurs at interface through donor-acceptor interactions.