Influence of pH-sensitive 4-aminothiophenol on the copper corrosion inhibition of hybrid sol–gel monolayers

Abstract

In the present work, 4-aminothiophenol was impregnated into hybrid sol–gel consisting of 3-glycidoxypropyltrimethoxysilane and tetraethoxysilane at acidic, neutral and basic pH, which were subsequently self-assembled over copper surface. The resultant hybrid sol–gel layers were ascertained using Fourier transform infrared and UV–visible spectroscopic techniques. The surface morphology, chemical composition and wettability were studied using scanning electron microscopy, atomic force microscopy, energy-dispersive X-ray spectroscopy and water contact angle analyses, respectively. The corrosion inhibitive behavior of the as-prepared layers was studied using electrochemical impedance spectroscopy and potentiodynamic polarization studies. These studies revealed that among the three pH regions examined, the maximum inhibition efficiency was achieved only at acidic pH. By appropriately tuning the pH of 4-aminothiophenol-impregnated hybrid sol–gel endures better copper corrosion protection.