Corrosion Inhibition of Stainless Steel by Ferrocene-Polyoxometalate Hybrid Molecular Materials – Experimental and First Principle Studies

Hybrid molecular materials are designed using ferrocene and polyoxometalates with Keggin moiety. The hybrid materials, synthesized in acidic medium by co-precipitation method, are charge transfer salts with formulae (referred as FcPW) and (referred as FcPMo). The molecular properties of these hybrid materials are investigated by various analytical methods. The corrosion inhibition property of these materials is studied by weight loss method, electrochemical impedance spectroscopy and Tafel plots. They show good corrosion inhibition on stainless steel plates (SS, 316 grade) when immersed in 0.5 M H2SO4 and Ringer’s solution. The corroded steel plates are analyzed using scanning electron and atomic force microscopy techniques to find the type and extent of corrosion. The type of corrosion is uniform and Tafel plots show inhibition efficiency as 84% for SS@FcPMo and 69% for SS@FcPW. The experimental results are corroborated by computational studies carried out using first principles with optimized geometry and frontier molecular orbitals of the hybrid molecular materials.