Electrochemical behavior and interfacial bonding mechanism of new synthesized carbocyclic inhibitor for exceptional corrosion resistance of steel alloy: DFTB, MD and experimental approaches

Abstract

A new carbocyclic compound, namely 3-benzoyl-4-hydroxy-4-phenyl-2,6-(4-methylphenyl)cyclohexane-1,1-dicarbonitrile (MPC) was synthesized and characterized. Herein, MPC was used as green compounds and its anti-corrosion performance was evaluated on the basis of singular role of electron donor–acceptor of MPC molecule. For this purpose, a combination of experimental studies and electronic-/atomic-scale calculations were performed in a bid to understand the electrochemical behavior and interfacial mechanism of MPC molecule based on the correlation between electron charge transfer and adsorption mechanism. Theoretical perspectives are also used to validate the significant inhibition feature achieved by the experimental studies and propose a mechanism of adsorption by using density functional theory (DFT) and molecular dynamic (MD) simulations. According to DFT and MD perspectives, it is found that MPC presents strong interaction with metal surface due to its considerable ability to provide lone pair electrons for electrophilic attacks. This is demonstrated by the high adsorption energy (-5.83 eV) and the parallel configuration of MPC which reveal the formation of molecular self-assembly triggered by an organic-surface interaction. The reliable corrosion stability was provided for 72 h of immersion at an optimum concentration with a fairly high inhibition efficiency (85.81 %) due to the formation of organic inhibitive layer. The addition of MPC inhibitor worked as a sealing agent to reduce the corrosion rate, thus forming a dense and protective barrier on the metal surface. The corrosion resistance of mild steel sample was enhanced significantly due to a high adsorption ability arising from the electron-rich nature of molecule. The formation of organic layer on the metal surface was discussed in relation to the intermolecular interactions and microstructural observations by considering the charge transfer behavior responsible for exceptional corrosion protection of steel alloys. The computational simulations were consistent with the experimental results and confirm the importance of developing eco-friendly hybrid materials.

Keywords

• Corrosion inhibitor
• Electron transfer behavior
• Interfacial mechanism
• Electronic-/atomic-scale calculations