Electrochemical, DFT and MD simulation of newly synthesized triazolotriazepine derivatives as corrosion inhibitors for carbon steel in 1 M HCl

The inhibitive action of three newly synthesized triazolotriazepine derivatives, namely, 9‑ethyl‑6‑methyl‑7H‑1,2,4‑triazolo[4,3‑b][1,2,4‑triazepin‑8(9H)-one (TTY), 7,9‑didecyl‑6‑methyl‑7H‑1,2,4‑triazolo[4,3-b][1,2,4]triazepin‑8‑one (TTY4), and 7,9‑ditetradecyl‑6‑methyl‑7H‑1,2,4‑triazolo[4,3‑b][1,2,4]triazepin‑8‑one (TTY5) for carbon steel in 1 M HCl is investigated using potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS) and surface analysis techniques. The results show that the corrosion of carbon steel in HCl solution is efficiently inhibited by these new organic inhibitors. The adsorption of tested inhibitors on carbon steel surface is found to be spontaneous and obeyed the Langmuir adsorption isotherm. The anti-corrosion mechanism of these new inhibitors on iron was further revealed by quantum chemical calculations and molecular dynamics simulations. In agreement with the experimental data, theoretical results showed that the order of inhibition efficiency is TTY5 > TTY4 > TTY.