Spent coffee grounds-derived N-doped carbon dots as efficient green corrosion inhibitors for Q235 steel in acidic environment

Carbon dots (CDs) are gaining considerable attention as green corrosion inhibitors, due to their eco-friendly nature and sustainable production methods. In this study, CDs were synthesized via the hydrothermal method using biomass waste, spent coffee grounds, as a carbon source, with polyaspartic acid as a nitrogen doping source. The chemical composition, fluorescence properties, and morphology of the synthesized spent coffee grounds-derived N-doped carbon dots (GCDs) were deeply characterized. Moreover, Electrochemical analysis and weight loss experiments were conducted to investigate the corrosion inhibition performance on Q235 steel in 1 M HCl. Our findings indicated that at a concentration of 10 mg/L, the corrosion inhibition efficiency reached 93.9 %. Additionally, the GCDs acted as mixed-type corrosion inhibitors, and the adsorption behavior was confirmed to the Langmuir adsorption model, where GCDs formed a stable protective film on the steel surface through chemical coordination with Fe atoms, thereby enhancing corrosion resistance. This work offers valuable insights into the development of environmentally friendly corrosion inhibitors to enrich their related applications.