Novel carbon dots as effective corrosion inhibitor for N80 steel in 1 M HCl and CO2-saturated 3.5 wt% NaCl solutions

In this work, the eco-friendly of functionalized carbon dots (N-CDs) was synthesized by the microwave method. The corrosion inhibition behavior of N-CDs for N80 steel in 1 M HCl and CO2-saturated 3.5 wt% NaCl solutions were systematically investigated by weight loss, electrochemical measurements and surface morphology. The results revealed that N-CDs exhibited outstanding inhibitory performance. The inhibitory efficiency in 1 M HCl and CO2-saturated 3.5 wt% NaCl solution at 70 °C reached 89.04% and 94.6% at 200 mg/L of N-CDs, respectively. Meanwhile, N-CDs was a mixed inhibitor that mainly suppressed the cathode in corrosion conditions (1 M HCl), while it was a mixed inhibitor that primarily inhibited the anode in the saline solution. In addition, based on the analysis and mechanism study of the surface of N80 steel, N-CDs followed the Langmuir adsorption isotherm and adsorbed on the metal surface through physical and chemical adsorption to inhibit corrosion, which fully explained the inhibition mechanism of N-CDs at metal/solution interface. Therefore, this work could provide new ideas for exploring efficient and environmentally friendly corrosion inhibitors.