Green synthesis of functionalized fluorescent carbon dots from biomass and their corrosion inhibition mechanism for copper in sulfuric acid environment

The design of new corrosion inhibitors for metallic copper is an important path to ensure that it is not corroded in a wide range of applications such as chemical and electronic industries. In this article, carbon dots with fluorescence properties are synthesized as corrosion inhibitors from green biomass through the hydrothermal method. This method does not generate a large number of waste solvents and toxic byproducts, and has excellent potential to replace other methods. Structural characterizations reveal that the biomass carbon dots (BCDs) contain a significant number of heteroatoms (such as N and S) and heteroatom-containing functional groups, which align with the general properties of corrosion inhibitors. The electrochemical analysis demonstrates an impedance value of 6314.1 Ω cm2 in a 50 mg/L BCD solution at 298 K, significantly higher than that observed in the blank solution, resulting in a corrosion inhibition efficiency of 92.97%. Morphological characterizations reveal that BCDs protect copper through adsorption and coordination film mechanisms. BCDs physically adsorb onto the copper surface and chemically coordinate with Cu+ to form a dense and ordered protective film. Notably, we utilize the fluorescence properties of BCDs as a probe to investigate the protective mechanisms of corrosion inhibitors on metals. Overall, the BCDs show great potential as eco-friendly corrosion inhibitors for copper protection, offering a new direction in corrosion research and practical applications.