Corrosion inhibition of eco-friendly nitrogen-doped carbon dots for carbon steel in acidic media: Performance and mechanism investigation

•Corrosion inhibition of carbon steel in 1 M HCl by new N-doped carbon dots was investigated.•The structure and morphology of NCDs were characterized by UV–vis, FTIR, XPS, XRD, and TEM.•Inhibition efficiencies were experimentally achieved by EIS and PDP techniques.•The adsorption behavior was demonstrated by XPS and Langmuir adsorption isotherms.•Surface characterizations were performed by SEM, AFM, and contact angle tests. In this work, nitrogen-doped carbon dots (NCDs) were obtained by hydrothermal method with citric acid and ethylenediamine as precursors. The corrosion inhibition performance and mechanism of prepared the NCDs on the Q235 carbon steel in 1 M HCl solution were evaluated by electrochemical impedance spectroscopy (EIS), potentiodynamic polarization curve, and surface analysis. The results that the NCDs exhibited 93% of inhibition efficiency at 100 mg/L. Electrochemical measurements demonstrated that the NCDs adsorbed on the metal surface and effectively inhibited the electron transfer process. The potentiodynamic polarization suggested that NCDs were excellent mix-type corrosion inhibition. Furthermore, NCDs successfully prevented the dissolution of anode metal and the evolution of cathode hydrogen ions. The adsorption of the NCDs followed Langmuir adsorption isotherm indicated physical and chemical adsorption. At the same time, the adsorption mechanism was analyzed, guiding the use of carbon dots as environment-friendly corrosion inhibitors in the future.