Nitrogen-doped carbon dots as high-effective inhibitors for carbon steel in acidic medium

Carbon dots (CDs), a new class of nanomaterials, are found to be good inhibitors. Given that there is no clear mechanistic explanation in the literature on how the CDs inhibit the corrosion of carbon steel in H2SO4 medium. Eco-friendly nitrogen-doped functionalized carbon dots (N-CDs) were facilely synthesized via the one-step hydrothermal reaction of two low-cost raw materials with multiple functional groups, i.e., citric acid and urea. Their corrosion inhibition behavior was systematically investigated via electrochemical methods and surface analysis. The resultant N-CDs were found to be an effective corrosion inhibitor for carbon steel in 0.5 M H2SO4 solution at 30 mg/L, with the inhibition efficiency exceeding 95 % at 298 K. The N-CDs can be adsorbed onto the steel surface by forming a barrier to prevent/ reduce the attack of corrosive ions, which follows the Langmuir adsorption model. Their inhibition mechanism was also proposed, providing a guide to search for new nanomaterials for metal against corrosion.