Novel carbon dots as efficient green corrosion inhibitor for mild steel in HCl solution: Electrochemical, gravimetric and XPS studies

Eco-friendly, good water soluble and inexpensive, carbon dots (CDMU and CDMH) were synthesized, characterized and applied as corrosion inhibitor for mild steel (MS) in 15% HCl solution. The characterization of both inhibitors was carried out by FTIR, UV–vis, photoluminescence, XPS and TEM. The average size of CDMU and CDMH were found as 2.03 and 2.5 nm, respectively. The inhibitive effect of CDMU and CDMH was evaluated by weight loss measurement, electrochemical impedance spectroscopy and potentiodynamic polarization measurement. Both CDMU and CDMH exhibited 97.89 and 90.10% of inhibition efficiency, respectively, at 100 mg/L concentration and 303 K temperature. Adsorption of CDMU and CDMH on MS surface followed Langmuir adsorption isotherm. The surface morphology of uninhibited and inhibited MS specimens was studied by the FESEM, AFM and XPS analysis. • Studied carbon dots, CDMU and CDMH act as efficient eco-friendly corrosion inhibitor. • CDMU and CDMH act as mixed inhibitors. • Adsorption of CDMU and CDMH obeyed Langmuir adsorption isotherms. • SEM, AFM and XPS studies suggested adsorption of inhibitor on MS surface.