Norfloxacin-Derived Carbon Dots with Rich Electron Pyrrolic Nitrogen for Copper Corrosion Inhibition and Antibacterial Functions

The coexisting anticorrosion and antibacterial functions are of great significance for the marine industry. Controllable surface negative charge and wettability of pyrrolic nitrogen-doped carbon dots (NCDs) derived from the single antibiotic norfloxacin precursor with a special nitrogen heterocyclic structure were successfully fabricated through the hydrothermal route. The incorporated functional groups and chemical bonds, surface charge, mechanism of pyrrole nitrogen ring formation at the molecular level, and antibacterial properties of NCDs were revealed by FTIR, XPS, zeta potential, LC-MS, and electrochemical techniques. The present corrosion efficiency (96.1%) in 3.5 wt % NaCl saline solution in the presence of air and N₂ or UO₂²⁺ is higher than most previously reported values. The proposed electron transfer corrosion mechanism suggests that the negative charge domains of NCDs were strengthened by the saltwater electron sink effect to repel chlorine and simultaneously a large number of electrons of NCDs were injected into copper as the electron reservoir based on energy-level matching, thereby avoiding Cu⁰ oxidization. Current works provide a guideline for exploring novel eco-friendly and highly efficient NCD corrosion inhibitor materials with antibacterial properties for safeguarding metals in seawater.