Insights into the Adsorption Mechanism and Corrosion Protection of Phytic Acid Conversion Coatings on Fe, Cu, and Al Surfaces: A Combined Theoretical and Experimental Study

This study explores the surface interaction mechanism of phytic acid (PA) on Fe, Cu, and Al metals and its applicability in green anticorrosion surface treatment through a combination of quantum chemical calculations, molecular dynamics (MD) simulations, and electrochemical measurements. Quantum chemical calculations identified the nucleophilic/electrophilic active sites of PA via HOMO-LUMO and Fukui functions. MD simulations then constructed solution-metal interface models, calculating adsorption energies, radial distribution functions, and the diffusion behavior of H2O and Cl− to elucidate PA’s adsorption configurations and its inhibition of corrosive species diffusion. Based on these theoretical insights, PA conversion coatings were in situ constructed on Fe, Cu, and Al substrates. Potentiodynamic polarization tests confirmed that these coatings effectively enhanced the corrosion resistance of the metals in a 3.5 wt% NaCl solution, achieving inhibition efficiencies of 92% for Fe, 86.5% for Al, and 26% for Cu. This work provides a comprehensive mechanistic interpretation from molecular adsorption to surface film formation, offering significant insights into environmentally friendly corrosion protection methods.