Valorization of the green corrosion inhibitor Marrubium vulgare L.: Electrochemical, thermodynamic, theoretical & surface studies

•The present study focuses on Marubium vulgare L as an effective green corrosion inhibitor for copper.•The inhibition efficiency increases with the concentration of the oil to reach a maximum value of 95.51 % at a concentration of 1 g/L.•The SEM-EDX analysis supports that the testing inhibitor provides an excellent protective film on the metal surface against corrosive attacks.•The calculated results (DFT) indicate that the studied inhibitor spontaneously adsorbs on the cu (111) surface.