Lycium barbarum leaf extract as biodegradable corrosion inhibitor for copper in sulfuric acid medium

Corrosion protection of metals is a significant research field that requires the development of safe, non-toxic, cost-effective, and environmentally friendly high-performance corrosion inhibitors. This study employed a water-based extraction method to obtain Lycium barbarum leaf extract (LBL) and utilized a series of experimental and theoretical approaches to evaluate its corrosion protection efficacy on copper in 0.5 mol/L sulfuric acid environments. The electrochemical tests unequivocally demonstrated the outstanding corrosion inhibition ability of LBL, with corrosion inhibition efficiencies of 92.9%, 92.8%, and 94.1% observed at a concentration of 400 mg/L and temperatures of 298 K, 303 K, and 308 K, respectively. Advanced techniques such as Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) were employed to comprehensively characterize the chemical composition and functional groups of LBL and the surface of copper samples immersed in the LBL. Furthermore, scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to observe and analyze the morphology of acid-corroded copper surfaces and those protected by LBL. As a supplement to the experimental findings, quantum chemical calculations and molecular dynamics simulations were employed to explore the theoretical aspects of the active constituents in LBL and simulate their adsorption behavior.