Theoretical Investigation of Geranium Essential Oil Compounds as Green Corrosion Inhibitors for Copper: Insights From DFT, Monte Carlo, and Molecular Dynamics Simulations

This study investigates geranium essential oil (GEO) as a potential corrosion inhibitor for copper in sulfuric acid (H₂SO₄) solution through computational modeling. Key compounds in GEO, including geraniol, β-citronellol, and (E)-citral, were identified and evaluated for their corrosion inhibition potential. Quantum chemical calculations using density functional theory (DFT) revealed that compounds with lower energy gaps and higher electrophilicity, such as (E)-citral, exhibit high reactivity and strong interaction with copper surfaces. The Fukui indices were also calculated to determine the reactive sites within each molecule, indicating that oxygen-containing functional groups are the most probable adsorption centers on the copper surface. Molecular electrostatic potential (MEP) and Monte Carlo simulations indicated that the inhibition mechanism is driven by physisorption via van der Waals and electrostatic interactions. Molecular Dynamics Simulations further confirmed the stability of the adsorbed molecules, suggesting the formation of a protective layer on the copper surface. These results highlight the potential of GEO as an eco-friendly corrosion inhibitor, necessitating further experimental validation through electrochemical and mass loss studies to confirm the theoretical findings.