Effect of external parallel electric field on corrosion inhibition of carbon dots for carbon steel in 1 M HCl solution

The behavior characteristics of nano-inhibitors are meaningful to understand the inhibition mechanism and influencing factors of particles in large size. Given the accumulated charge in the outer layer of nanoparticles, the driving force in the electric field will be significantly different from that in traditional inhibitors, and the process of adsorption kinetic will be inevitably changed. In this study, the carbon dots (CDs) were used as the nano-inhibitor for carbon steel in 1 M HCl solution, and the effect of external parallel electric field (PEF) for inhibition performance had been investigated via the various measurements. The results revealed that CDs can effectively inhibit metal corrosion, and the inhibition efficiency reached 90% at only 5 mg/L. Chemisorption and chelation of polar groups in CDs lead to the accumulation, then forming the protective cover layer on metal surface. But the inhibition performance of CDs declined gradually with the increase of electric intensity of PEF, and inhibition efficiency decreased by about 20% according to the results in polarization curve when the electric intensity was in 2 × 10 5 V/m. The migration direction and aggregation concentration of CDs were affected by the electric field, and there was horizontal force during the adsorption of nanoparticles under PEF, thus the adsorbing performance at the interface weakening with the defective cover layer. Graphical abstract