Anti-corrosive properties of novel nano-B/N/S-doped and heterocycle-functionalized carbon dots: a combined DFT and MD simulation study

In this work, two series of new potential nano-carbon dots (CDs) inhibitors with different sizes (series A: five rings; series B: ten rings), doped elements (B, N and S) and functional groups (–OH, –COOH, –CO-thiazole, –CO-imidazole) were designed. Their various anti-corrosive properties, corrosion inhibition efficiencies and mechanisms were investigated by DFT and MD. The results showed that the B-doping and S-doping could significantly improve the feedback bonding, while the N-doping can enhance the feedback and coordinate bonding. Most of CDs could be either solid nucleophiles or nucleophiles; their anti-corrosive parameters and adsorption energies are much better than common organic inhibitors, indicating their high value to be used as new inhibitors. Most CDs not have high ∆N (Fe) and high ∆N (Cu) and may be why some CDs can inhibit the corrosion to both Fe and Cu alloys. CDs in series B have better softness, ∆N and ∆E, than the corresponding ones in series A, suggesting the significant effect of the size, and it is necessary to consider this when using CD inhibitors. Finally, the N-doping, S-doping and B-doping influenced the structures, leading to different corrosion inhibition mechanisms.