A novel effective carbon dots-based inhibitor for carbon steel against chloride corrosion: From inhibition behavior to mechanism

Reinforced concrete (RC) structures suffer from serious chloride corrosion. Corrosion inhibitors can effectively protect reinforcement against chloride corrosion, thus improving the durability of RC structures. Benefiting from their environmental friendliness, simple preparation, and high inhibition efficiency, carbon dots (CDs) as a promising green corrosion inhibitor have attracted intensive attention. However, there is no investigation on the corrosion inhibition performance and mechanism of CDs in a chloride-contaminated alkaline medium for carbon steel, thereby hindering their application in RC structures. In the current research, CDs as a novel effective corrosion inhibitor were first applied to protect carbon steel in a chloride-contaminated simulated concrete pore solution (Cl-SCPS). Specifically, their inhibition behavior was investigated using electrochemical impedance spectra and potentiodynamic polarization measurements; And the inhibition mechanism was revealed by adsorption isotherm analysis, corrosion morphology study, and theoretical calculation. Results showed that CDs could achieve long-term inhibition efficiency of 99.2 % only at 400 mg/L on carbon steel in Cl-SCPS. Notably, the inhibition mechanism of CDs was ascribed to their stable adsorption on Fe (110) or γ-FeOOH (010) surfaces of carbon steel, with significantly higher Ebinding absolute values compared to previous literature. This research provided a novel high-performance inhibitor, as well as the facile synthesis method, to effectively mitigate chloride corrosion of carbon steel, expected to improve the durability of RC structures.