Electrochemical and in silico investigations into the corrosion inhibition of cyclic amino acids on tin metal in the saline environment

Abstract In the current study, the inhibition properties of three cyclic amino acids, namely Histidine (His), Tyrosine (Tyr) and Phenylalanine (Phe), have been investigated using electrochemical techniques for tin corrosion in stagnant 2% NaCl solution at different pH values. To shed more light on the inhibition mechanism, DFT-based computations and Monte Carlo-SAA simulations have been employed. The obtained data revealed that His and Phe compounds have shown the maximum of the inhibition effectiveness at pH 2 and 5, respectively. Besides, without exception, all studied inhibitors have exhibited higher prevention values at pH 5 as compared to pH 2, which was attributed to the ability of those compounds to form hydrogen bonds and interact effectively with the metal surface (SnO2) at pH 5. Furthermore, due to the complexity of the inhibition phenomena, the analysis of calculated intrinsic quantum parameters cannot be used to explain the almost observed inhibition behavior of the studied inhibitors set. On the other hand, agreeing with our results, the conjoint analysis of energetic and geometrical aspects of the adsorption of an inhibitor molecule onto the metal surface is required to get clear insights on the inhibition process.