Amino acids as copper corrosion inhibitors: A density functional theory approach

[Display omitted] •Cysteine (CYS), glutamic acid (GLA), glycine (GLY) and their derivative glutathione (GLT) as corrosion inhibitors for copper.•Experimental inhibition efficiency trends successfully predicted using DFT.•O, S and N-atoms of amino acids make chemical bond with Cu (1 1 1) surface atoms.•Electron density difference and PDOS plots confirmed the chemical nature of interaction. Density functional theory was employed to investigate the corrosion inhibition mechanisms of four amino acids, viz. glutamic acid, cysteine, glycine, and their derivative glutathione. Quantum chemical descriptors such as highest occupied molecular orbital (HOMO) energy, lowest unoccupied molecular orbital (LUMO) energy, and energy gap (ΔEgap) were calculated to establish the relationship between the descriptors and corrosion inhibition efficiency. Further, in order to understand the adsorption mechanisms of amino acids with the copper surface, detailed adsorption studies were performed on Cu (1 1 1), Cu (1 0 0) and Cu (1 1 0) surfaces. The computed quantum chemical descriptors and the adsorption energies successfully predict the experimental inhibition efficiency trends. The optimized structures show formation of chemical bonds between the O, S, and N-atoms of the molecules and Cu (1 1 1) surface, confirmed by electron density difference and projected density of states plots Besides, the trends in computed adsorption energy were found to be unaffected by surface coverage studied by adsorbing multiple molecules (1–3) on Cu (1 1 1) surface.