Nitrogen/Sulfur Co-Doped Carbon Dots for Enhancing Anti-Corrosion Performance of Mg Alloy in NaCl Solution

To reduce the corrosion of Mg alloy, an environment-friendly Nitrogen/Sulfur co-doped carbon dots (N/S-CDs) was prepared using thiourea and 4-amino salicylic acid as precursors. The corrosion inhibition behavior of N/S-CDs for Mg alloy in 3.5 wt.% NaCl solution was systematically investigated by electrochemical measurements. The results shown that N/S-CDs could suppress the corrosion of Mg alloy and the inhibition efficiency reached 86.6 % at 50 mg L-1. The low energy gap (0.156 eV) and high dipole moment (11.19 D) indicated that N/S-CDs has a strong chemical adsorption on Mg by quantum chemistry calculation. Meanwhile, the adsorption process is conformed to the Langmuir adsorption isotherm, belonging to the physical/chemical mixed adsorption.