By using 2-[(4-carboxyl)phenyl iminomethylene]phenoxyacetic acid(K2L1)as corrosion inhibitor

the self-assembled monolayers(SAMs)were prepared on the surface of 20# carbon steel

and the influence factors of the inhibition film

i.e.

synthesis conditions of corrosion inhibitor and best self-assembly time were investigated by electrochemical method.The molar ratio of KOH to o-formylphenoxyacetic acid was 2:1 for the synthesis of the K2L1 inhibitor

and a fairly dense stable inhibition film of SAM could be formed on carbon steel surface after 3 h immersion.The research of corrosion inhibition indicated that K2L1 SAMs changed the structure of the double-electric layer on carbon steel electrode surface.In addition

SAMs restrained the process of cathodic reduction and had good anticorrosion effect with the highest inhibition efficiency up to 95%

which was in good agreement with the results obtained by EIS and polarization curve methods.Electrochemical measurements indicated that the corrosion resistance for carbon steel electrode was enhanced by the K2L1-SAMs. Adsorption behavior of the K2L1-SAMs followed the Langmuir's adsorption isotherm

and the adsorption mechanism was typical chemisorption.Quantum chemistry calculation result showed that K2L1 molecule had planar structure with a number of active centers

and their frontier orbitals could interact with those Fe atom on the surface of carbon steel.Thus they might form an adsorption barrier film on the carbon steel surface to decrease the corrosion rate of carbon steel.X-ray photoelectron spectroscopy showed that the stable inhibition film by K2L1 on carbon steel surface was due to the formation of coordination bond.