Synthesis of novel carbon dots as efficient green corrosion inhibitor for mild steel in an acidic environment: Electrochemical, gravimetric, and XPS analysis

Carbon dots CDLP and CDLT were synthesized by one-step hydrothermal synthesis process. These carbon dots worked as water-soluble, inexpensive, and eco-friendly corrosion inhibitors when dissolved in a 15 % HCl solution to inhibit the mild steel (MS) corrosion process. The synthesized CDLP and CDLT were characterized by FTIR, UV–Vis, PL, XPS, and HRTEM analysis. Potentiodynamic polarization analysis, electrochemical impedance spectroscopy analysis, and weight loss measuring analysis were used to determine the inhibition efficiency of CDLP and CDLT. At 120 ppm concentration and 303 K temperature, the inhibition efficiency of CDLP and CDLT was observed as 96.50 % and 90.21 %, respectively. The adsorption of CDLP and CDLT on the MS surface followed mixed adsorption (physisorption and chemisorptions) and obeyed the Langmuir adsorption isotherm. According to the potentiodynamic polarization investigation, CDLP and CDLT act as mixed-type inhibitions, reducing simultaneously the rate of MS dissolution and hydrogen evolution reaction on the anodic and cathodic sites, respectively. The surface morphology of inhibited samples was analyzed using FESEM, EDX, AFM, and XPS studies and existence of a protective inhibitor layer on the MS surface was confirmed.