N-doped and Cu,N-doped carbon dots as corrosion inhibitor for mild steel corrosion in acid medium

In the present study, N-doped carbon dots (N-CDs) and Cu,N-doped carbon dots (Cu,N-CDs) with various Cu doping amounts were explored as corrosion inhibitors for mild steel substrate. Material characterizations of synthesized materials were performed using UV-Vis, FTIR and XRD, TEM and XPS techniques. Electrochemical corrosion testing showed enhanced corrosion inhibition performance for Cu,N-CDs relative to N-CDs. The inhibition efficiencies were directly proportional to concentrations of N-CDs and Cu,N-CDs, with more than 97% achieved at 100 ppm of Cu,N-CDs. Gravimetric measurements at temperatures ranging from 40 to 70 ℃ revealed a slight increase in inhibition efficiencies from 99.5 % to 99.7 % for higher Cu doped Cu,N-CDs. Protective nature of N-CDs and Cu,N-CDs was accredited to physicochemical adsorption and inhibitor film formation. In addition, the growth of an electroless like Cu deposit on the mild steel surface contributed to better inhibition performances of Cu,N-CDs. The inhibition mechanism was supported by surface characterization of inhibited steel substrate.