N,P,S co-doped carbon dots as a eco-friendly and novel inhibitor for metal protection: Experimental and simulation analysis

Copper corrosion in chloride environments necessitates efficient and eco-friendly inhibitors. This study first proposes nitrogen, phosphorus, and sulfur co-doped carbon dots (N,P,S-CDs) as a novel inhibitor for copper in 3.5 wt% NaCl solution, filling a gap in the application of ternary-doped nanomaterials in representative neutral chloride media. The structure and performance of N,P,S-CDs were systematically compared with those of single (N-CDs) and dual-doped (N,S-CDs, N,P-CDs) carbon dots. A multi-scale investigation combining electrochemical tests, surface morphology analysis, and theoretical simulations was conducted to elucidate the corrosion inhibition mechanism. Results demonstrated that N,P,S-CDs achieved an optimal inhibition efficiency of 96.15% at 200 mg/L. The ternary doping strategy enhanced the chemical adsorption capability of CDs onto the metal surface through a synergistic effect, resulting in the formation of a compact and stable protective film that effectively blocked the attack of corrosive species. This work provides novel insights into the design of high-performance green corrosion inhibitors via multi-element synergistic doping.