Experimental and DFT studies of porous carbon covalently functionalized by polyaniline as a corrosion inhibition barrier on nickel-based alloys in acidic media

Abstract

In acidic medium, nickel alloys severely suffer from long term corrosion problems as a result of the breakdown of their passivating oxide. The present study considers polyaniline functionalized fish-scale graphitic carbon as an anticorrosion coating on the nickel alloy surface. The fish-scale porous carbon materials are characterized by XRD, ATR-FITR, UV, Raman, TGA, SS NMR, FESEM, and TEM methods. The surface of the alloy is covalently bound with a polyaniline long chain protonated polymer so that the polyaniline functionalized honeycomb fish-scale carbon structure can exchange electrons with the metal surface. The corrosion inhibition efficiency has been investigated in different acid media like sulfuric acid and hydrochloric acid by electrochemical methods. Polyaniline functionalized porous carbon showed in 1 M H₂SO₄ inhibition efficiency around 64% and in 1 M HCl inhibition efficiency was around 74%. The inhibition efficiency was higher in HCl because chloride ions were not able to penetrate the graphitic sheet. The novelty of this coating is in the fact that the polyaniline functionalized porous carbon has high conductivity and is electrochemically stable in acidic medium. It is able to donate electrons to the polarized metal surface.