Sulfosalicylic acid modified carbon dots as effective corrosion inhibitor and fluorescent corrosion indicator for carbon steel in HCl solution

In this work, a novel carbon dots based complex with sulfosalicylic acid modification (CDs-SSA) was synthesized, endowing it with both corrosion inhibition and corrosion sensing abilities. The corrosion inhibition behaviors of CDs-SSA for carbon steel in HCl solution were investigated using electrochemical methods, surface characterization and molecular simulation. Compared with CDs, SSA and their mixture, the corrosion inhibition performance of CDs-SSA complex was greatly improved, showing the anodic passivation behavior and much increased impedance modulus. The corrosion inhibition efficiency of CDs-SSA reached the maximum of 99.1% at 200 mg/L after 24 h of immersing the steel in 1 M HCl solution. According to surface analyses results, CDs-SSA provided a superior corrosion inhibition effect via developing a physicochemical adsorption film with hydrophobicity to prevent the attack of corrosive media. Meanwhile, DFT and MD simulations clarified that the CDs-SSA complex with abundant active sites would adsorb on the metal surface in a parallel manner, offering the maximum coverage with highest binding energy. Furthermore, CDs-SSA could visually and sensitively respond to both Fe2+ and Fe3+ ions, which illustrated a prominent fluorescence quenching effect upon complexation with iron ions.

Automated summary

A novel carbon dots based complex with sulfosalicylic acid modification was synthesized, which showed both corrosion inhibition and corrosion sensing abilities. The corrosion inhibition behavior of the complex was greatly improved compared to carbon dots, sulfosalicylic acid, and their mixture. The complex formed a hydrophobic adsorption film to prevent the attack of corrosive media, and it exhibited high coverage and binding energy on the metal surface. Additionally, the complex showed a significant fluorescence quenching effect upon complexation with iron ions.