Improved corrosion resistant performance of mild steel under acid environment by novel carbon dots as green corrosion inhibitor

A novel eco-friendly, water soluble and effective corrosion inhibitor N, S-CDs was synthesized by hydrothermal method. The characterization of N, S-CDs was carried out by Fourier transformation infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV–vis) spectroscopy, photoluminescence (PL), Raman spectroscopy, X-ray photo electron spectroscopy (XPS) and high resolution transmission electron microscopy (HRTEM). The inhibitive effect of N, S-CDs on mild steel (MS) corrosion was evaluated by weight loss analysis, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization methods in 15% HCl solution. As per potentiodynamic polarization studies, studied inhibitor acts as mixed type inhibitor. Investigated N, S-CDs exhibited 98.64% of inhibition efficiency at 200 mg / L concentration and 303 K temperature. Investigated N, S-CDs corrosion inhibitor shows better corrosion inhibition efficiency as compared to the most of the similar type of corrosion inhibitors already reported in literature. The adsorption of N, S-CDs on MS surface followed Langmuir adsorption isotherm. The surface morphology of MS specimens was studied by scanning electron microscopy (SEM), atomic force microscopy (AFM) and contact angle measurement.