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.