Combined experimental, theoretical, & machine learning studies of anticorrosion properties of hydroxyethyl cellulose, l-glutamic acid, & potassium acesulfame-derived carbon dots

This study investigates the corrosion inhibition performance of l-Glutamic acid (GA), potassium acesulfame (AK), hydroxyethyl cellulose (HEC), and novel N, S co-doped carbon dots (N, S-CDs) on carbon steel (CS) and stainless steel (SS) in 1 M HCl. While GA and AK individually inhibited CS (86–87 % efficiency (η) via adsorption) but accelerated SS corrosion (−66 % to −70 %) due to chelation-driven dissolution and cathodic activation, their combination with KI reversed SS corrosion acceleration to inhibition (42–44 %) through synergistic co-adsorption. To address this metallurgical specificity, N, S-CDs were synthesized from HEC, GA, and AK, demonstrating exceptional dual inhibition (90 % for CS, 66 % for SS at 0.5–1.0 mg/L) via chemisorption, which forms protective films, as validated by TEM/AFM and XPS. X-ray photoelectron spectroscopy (XPS) and computational modeling (DFT, MD simulations) reveal N, S-CDs’ planar adsorption, Fe–N/S bonding, and electron donation as key mechanisms. Machine learning identified inhibitor concentration as the dominant predictor of efficiency, highlighting the importance of surface coverage dynamics. The N, S-CDs exhibit thermal resilience (97 % η for CS at 60 °C by 1.0 mg/L) and prolonged stability (98 % for CS at 72 h by 0.5 mg/L), outperforming conventional inhibitors. This work introduces N, S-CDs as a novel, eco-friendly solution for multi-metallurgical corrosion protection, bridging the gap between organic inhibitors’ limitations and the demand for adaptive, high-performance materials in aggressive environments.