Hybrid organic-inorganic nano-interfaces engineered from nitrogen doped carbon dots for sustainable corrosion mitigation

초록

The widespread use of toxic and environmentally harmful inhibitors for corrosion protection in various industrial acidizing, descaling, and pickling processes prompted the development of more sustainable and efficient green inhibitors. Herein, nitrogen-doped carbon dots (N-CDs) were produced via one-step hydrothermal reaction using citric acid, aspartic acid, and urea as precursors and used as a novel green corrosion inhibitor in 15 % HCl for mild steel (MS). HR-TEM images showed that spherical N-CDs of approximately 12 nm diameter size were formed. N- and O-containing surface groups identified by FTIR and XPS enhanced adsorption capacity. Optical studies revealed exciton-dependent fluorescence, signifying stable surface states. Gravimetric studies revealed higher corrosion inhibition efficiency with an increase in N-CD concentrations, where maximum efficiencies of 94.4 % and 96.6 % were achieved at 250 ppm and 400 ppm, respectively, under 303 K temperature conditions for corrosion rate of 46.8 mm/y (blank). Electrochemical investigations confirmed these observations. The Rct value was measured as 5.9 Omega cm2 for the blank sample. Which increased up to 119.5 Omega cm2 at 250 ppm N-CDs. The corrosion current density (icorr) was reduced from 825 & micro;A/cm2 (blank) to 38 & micro;A/cm2 leading to 95.4 % corrosion inhibition efficiency. N-CDs were observed to form an organic-inorganic hybrid protective layer onto the MS surface, which acts as a physical barrier against aggressive chlorine ion attacks. Density functional theory (DFT) analysis of N-CDs indicated suitable electronic properties such as good HOMO-LUMO energy levels (Delta E = 2.01 eV) and high electrophilicity values (psi = 6.64 eV).

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