N, S Co-doped carbon coated MnS/MnO/Mn nanoparticles as a novel corrosion inhibitor for carbon steel in CO2-saturated NaCl solution

As the scientific problems aroused in the aspects of interface behavior, colloidal properties and material structures, the novel nano-inhibitors have attracted a lot of attention gradually. Given the diversity of nanomaterials and their structures, the investigations about the inhibition mechanisms of nano-inhibitors besides the traditional adsorption are conducive to improving the basic research of inhibitors discipline system. In this study, N, S co-doped carbon coated MnS/MnO/Mn nanoparticles (MnS/MnO/Mn@SNC) were synthetized via the sol-gel method and later pyrolysis-sulfurization/oxidation. Diversified measurements have been adopted to investigate the inhibition performance of MnS/MnO/Mn@SNC for carbon steel in CO2-saturated 3 wt% NaCl solution, and the results confirmed that MnS/MnO/Mn@SNC can effectively inhibit corrosion, while the inhibition efficiency was more than 90% at 200 mg/L. The various immersion time and addition concentration have been applied to analyze the differences of inhibition effect. From the observation and analysis of surface, lamellar nanomaterials containing the simple substance of Mn have accumulated at interface along with the transformation from MnS to FeS, which were respectively served as anode material and dense corrosion product to protect the carbon steel. Besides that, the accumulations of carbon complex material have formed a hydrophobic film with special micro-nano structures. The probable model of MnS/MnO/Mn@SNC on metal surface was established to discuss the actual inhibition mechanism.