Biomolecules-modified carbon dots for enhanced surface and interface properties and sustainable corrosion protection: Experimental and computational studies

The present study describes the anti-corrosive properties of tyrosine and leucine functionalized glucose-derived carbon dots, abbreviated as CD_Tyr and CD_Leu, respectively, for Q235B steel in a 5 % HCl solution. ¹H-NMR, FT-IR, UV–vis, zeta potential, XRD and TEM analysis confirmed the preparation of functionalized CDs. The inhibition efficiencies and corrosion rates were calculated using mass loss and electrochemical methods. The inhibition effectiveness calculated for CD_Tyr and CD_Leu were, i.e., 96.8 % and 93.6 %, respectively, at 303 K at a very low concentration of both CDs, i.e., at 80 ppm. On increasing temperature from 303 to 313 K, corrosion rates decreased to 0.303 mm/y for CD_Tyr and 1.11 mm/y for CD_Leu, with %IE values of 97.84 % and 92.10 %, respectively. The experimental data from the immersion time test indicated that the CDs demonstrated consistently stable performance under static and dynamic conditions. Adsorption studies confirmed the spontaneous interaction and followed the Langmuir adsorption isotherm. The XPS analysis revealed the composition of the inhibitors’ layer on the metals surface. AFM and SEM studies demonstrated reduced surface roughness. CD_Tyr outperformed CD_Leu due to the phenolic group enabling stronger hydrogen bonding and improved protective layer stability. DFT and MD simulations provided insights into CDs’ electronic structure and stability derived from glucose and amino acid precursors, revealing distinct electronic characteristics.