Inhibition behavior of nitrogen-doped carbon dots on X80 carbon steel in acidic solution

Abstract

In order to restrain the corrosion issue in the picking process of metal materials, nitrogen-doped carbon dots (NCDs) with a size of 2 ~ 4 nm have been fabricated via hydrothermal synthesis with citric acid and thiourea as precursors. The corrosion inhibition behavior of NCDs on X80 carbon steel were investigated in 0.1 M HCl solutions with electrochemical experiments, the weight loss method, and surface morphology analysis. The Tafel curves showed that the inhibition efficiency reached as high as 92.98% at the NCDs concentration of 10 mg·L−1, indicating that NCDs had significant anti–corrosion capacity for X80 carbon steel. Impedance spectroscopy data revealed that the diameter of the capacitive reactance increased with increasing the NCDs concentration. More corrosion inhibitor molecules can be adsorbed on the metal surface instead of water molecules, which enhanced corrosion resistance of carbon steel. Weight loss experiment and surface morphology analysis strongly supported the results of electrochemical experiments. In addition, the NCDs adsorption at X80 surface followed the Langmuir adsorption isotherm, which was mainly dominated by physical adsorption.