Na-CDs as an eco-friendly and efficient corrosion inhibitor for Q235 in 1 M HCl

In this study, a novel type of green and highly efficient Na-CDs corrosion inhibitor was successfully prepared using a hydrothermal method, and its properties were thoroughly characterized. The results revealed that the Na-CDs possessed a uniform nanoscale size distribution and a well-defined graphene lattice structure. The corrosion inhibition performance of Na-CDs at varying concentrations was assessed, and it was found that the corrosion inhibition efficiency initially increased with the increase of concentration, peaking at over 96 % when the concentration reached 150 mg/L, before subsequently declining. Analysis of the adsorption behavior of Na-CDs on the metal surface confirmed that the adsorption process followed the R-P adsorption isotherm, indicative of an almost ideal homogeneous monolayer adsorption. The corrosion inhibition mechanism is the result of forming a protective film on the metal surface by physical adsorption and chemical adsorption, with the bridging role of Cl- further reinforcing the structure of this film. However, at excessively high concentrations of Na-CDs, desorption occurred, compromising the integrity of the protective film. This study enriches the field of metal-doped carbon dots as corrosion inhibitors and provides insights into the synthesis of carbon dots and the development of carbon dot-based corrosion inhibitors.