Crataegus oxyacantha leaves extract for carbon steel protection against corrosion in 1M HCl: Characterization, electrochemical, theoretical research, and surface analysis

•Electrochemical and theoretical behaviors of the carbon steel was investigated in 1 M HCl solution using the COL extract.•This extract was analyzed using UHPLC/DAD/ESI-MS technique; it was found that the extract contains 9 compounds.•The outcomes show that COL extract exhibits a worthy anti-corrosion action with an inhibition efficiency of 94% at 3 g/L.•The inhibition and adsorption behavior of the major constituents of COL extracts on iron surface was emphasized using DFT and MC studies. Plant extracts have become a source of green inhibitors that guarantee highest anti-corrosion efficiency. In the present study, we characterized the phenolic compounds of the aqueous extract from the Crataegus oxyacantha leaves (COL) by UHPLC/DAD/ESI-MS and we evaluated their inhibitory activity of carbon steel corrosion in the 1M HCl medium. The UHPLC/DAD/ESI-MS and FT-IR were used to determine of the composition of aqueous extracts from COL. For the inhibitory test of corrosion we used the weight loss study, the electrochemical study (potentiodynamic and impedance), the surface analysis (SEM-EDS, UV-Visible) and quantum chemical calculations. The results showed that COL extract contains nine phenolic compounds (flavonoids and phenolic acid). Weight loss corrosion and electrochemical tests revealed that the maximum protection efficiency of the steel achieved a 94% at 3 g/L concentration of COL extract at 298K.The values ofΔGads0, Ea, ΔHa and ΔSa demonstrate an endothermic phenomenon and controlled by physisorption process. Finally, the surface analysis confirmed that the surface metallic is protected and maybe the inhibitor molecules in COL extract form bonds with the metal surface. Theoretical study backed with the experimental results.