Litchi Shell-Derived Carbon Quantum Dots as Green Corrosion Inhibitors for 5052 Aluminum Alloy in Hydrochloric Acid Solution

The study utilized litchi shells as precursors to synthesize N, S self-doped carbon quantum dots (LBCQDs) by a hydrothermal method for use as corrosion inhibitors. Electrochemical testing, weight loss tests, surface characterization, and density functional theory calculations were employed to investigate the corrosion inhibition performance of LBCQDs on 5052 aluminum alloy in the HCl solution. The results indicate that LBCQDs are a mixed-type corrosion inhibitor, predominantly inhibiting cathodic reactions. Their corrosion inhibition efficiency increases with concentration, reaching a maximum of 94.22% at a concentration of 300 mg·L^-1. In addition, higher concentrations of LBCQDs result in a slower reduction in corrosion inhibition efficiency over a prolonged immersion time. The corrosion inhibition mechanism analysis indicates that LBCQDs can spontaneously form a protective film on the aluminum alloy surface based on the synergistic effects of physical adsorption, chemical adsorption, aggregation effect, and the chelation reaction. This increases the energy barrier of the corrosion reaction of the aluminum alloy, thereby inhibiting corrosion. This work not only provides a high-value utilization strategy for litchi shell biomass but also offers profound insights for designing eco-friendly corrosion inhibitors.