Ce-doped carbon dots enhanced by ionic liquids: A potent corrosion shield for N80 steel in aggressive 1M HCl environment

Carbon dots (CDs) have been studied as eco-friendly corrosion inhibitors for metals. However, the mechanisms behind their effectiveness are not fully understood. We developed a cost-effective and environmentally friendly method to synthesize Ce-doped CDs (CeCDs) using urea, ammonium citrate, and cerium nitrate. By optimizing the Ce doping concentration to 200 μg/L, we achieved a high corrosion inhibition efficiency. When tested in 1 M HCl, CeCDs at 200 mg/L showed 80 % inhibition, while ionic liquid-modified CeCDs (IL-CeCDs) demonstrated an even higher efficiency of 95.35 % on N80 steel. Both CeCDs and IL-CeCDs adsorb onto metal surfaces through a combination of physical and chemical interactions, inhibiting corrosion mainly by affecting cathodic reactions. Among different Ce-doped CDs, CeCD3N, which has a single Ce atom doping, exhibited the highest molecular reactivity, allowing it to interact more effectively with the Fe surface. Further analysis revealed that Ce doping reduces the energy gap of CDs, enhancing their reactivity. Molecular dynamics simulations showed that CeCD3N adsorbs more strongly and forms a closer inhibitor film on the Fe surface compared to other Ce-doped CDs, making it an effective corrosion inhibitor.