Experimental and theoretical elucidation on the inhibition mechanism of 1-methyl-5-mercapto-1,2,3,4-tetrazole self-assembled films on corrosion of iron in 0.5Â M H2SO4 Solutions

The self-assembled films of 1-methyl-5-mercapto-1,2,3,4-tetrazole (MMT) were prepared on the iron surface. By means of electrochemical impedance spectroscopy in 0.5 M H2SO4 solutions, the inhibition ability of the film was investigated. Results were discussed through changing the concentrations of the inhibitor and the pH values of the self-assembly solutions. Quantum chemical calculation was applied to elucidate the adsorption mechanism of the inhibitor molecule to iron atom. The study shows that MMT is a good inhibitor for iron in 0.5 M H2SO4 solutions. The self-assembled films formed in 10−2 M acidic solutions have the best protection effect and the inhibition efficiency in 0.5 M H2SO4 solutions is 98.0%. Density functional theory proves that MMT molecule is adsorbed on the iron surface by the most negatively charged nitrogen atom and the adsorption can occur spontaneously.