•Click synthesis of 1,2,3-triazole derivative inhibitors.•Pyridyl-substituted triazole derivative exhibits higher inhibition efficiency.•Triazole segments orient to mild steel surface in a parallel mode.•Pyridine segment significantly enhances adsorption of triazole derivative on iron.(1-Benzyl-1H-1,2,3-triazole-4-yl)methanol (BTM) and (1-(pyridin-4-ylmethyl)-1H-1,2,3- triazole-4-yl)methanol (PTM) were prepared and investigated as corrosion inhibitors for mild steel in 1.0 M HCl. It is found that PTM functions as more effective inhibitor than BTM in the concentration range of 0.2 −1.0 mM. Computational chemistry studies show that the triazole derivatives can adsorb on the mild steel surface by sharing the lone pair electrons of N atoms with iron atoms or by accepting electrons from iron surfaces. Due to its strong interaction with the mild steel surface in aqueous system, the pyridine segment should be responsible for the higher inhibition efficiency of PTM.

•Inhibition performance of long-chain alkyl-substituted benzimidazole.•Benzimidazole segment donating electrons to metal surface.•Non-polar long chain enhancing inhibition by the barrier effect.•Molecular form of DBI more tightly adsorbs on the steel than its protonated form.The corrosion inhibition of a new benzimidazole derivative, 6-(dodecyloxy)-1H-benzo[d]imidazole (DBI), for mild steel in 1 M HCl was investigated in this paper. Computational chemistry was performed to explore the adsorption of DBI on metal surface. Inhibition performance of DBI is attributed to both the direct interaction of benzimidazole segment with iron surface and the barrier effect of the non-polar long chain against aggressive solution. Compared to the protonated form, the molecular form of DBI could more tightly interact with iron surface. These results show that the long-chain alkyl-substituted benzimidazole derivative is of great potential application as corrosion inhibitor.

•Electrodeposition of PAni/PPy doped by phosphotungstate (PW12) on mild steel.•Introduction of PW12 improves the conductivity of conducting coatings.•OCPs of conducting coatings shift toward positive with the incorporation of PW12.•PAni/PPy-PW12 exhibits better corrosion resistance than PAni-PW12/PPy.Polyaniline/polypyrrole (PAni/PPy), polyaniline-phosphotungstate/polypyrrole (PAni-PW12/PPy) and PAni/PPy-PW12 have been successfully electrodeposited on mild steel (MS) by cyclic voltammetry in aqueous oxalic acid solutions. It was found that the incorporation of PW12 enhanced the corrosion resistance of PAni/PPy coating. Moreover, in comparison to PAni-PW12/PPy, PAni/PPy-PW12 coating exhibited better corrosion resistance for mild steel. After immersion of 36 h in 0.1 M HCl, for instance, the polarization resistance of PAni/PPy-PW12 coating reached 1695 Ω cm2, more than those of both PAni/PPy and PAni-PW12/PPy.

•Titanate matrices acting as corrosion inhibitor nanocontainers.•Stable matrix structure during both incorporation and extraction of inhibitor.•Dependence of release rate of inhibitor on pH of solution.Layered titanates as inhibitor nanocontainers were studied in this paper. Pyridine as a typical inhibitor was introduced into the titanate matrices and its extraction from the matrices was studied. The results show that the increase of pH of media favors the extraction of pyridine from the matrices. The layered structure of titanate containers remains stable after both introduction and extraction of pyridine. Additionally, corrosion inhibition measurements also confirm the effective release of pyridine from the titanate nanocontainers.

•Quantum chemical and MD studies of benzimidazole derivatives inhibitors.•Inhibition effectiveness depends on the ability to accept electrons.•Active sites of adsorption are mainly centralized on imidazole rings.•Steric effect results in the non-planar adsorption of BBIA and TBIA.In this paper, the adsorption behavior and inhibition mechanism of 2-aminomethyl benzimidazole (ABI), bis(2-benzimidazolylmethyl) amine (BBIA) and tri-(2-benzimidazolylmethyl) amine (TBIA) on the surface of mild steel were studied by quantum chemical calculations and molecular dynamics (MD) simulations. It was found that the three molecules show the similar ability to donate electrons while the difference in inhibition performance should mainly be attributed to the difference in accepting electrons. MD simulations show that steric effect between the benzimidazole segments significantly affects the adsorptive configurations of the molecules on Fe (1 0 0) surface.

Polypyrrole (PPy) coating and PPy composite coatings were successfully electrodeposited on mild steel in the electrolytes of oxalic acid in the absence and presence of dopants using cyclic voltammetry. Two types of doping ions were employed: phosphotungstate (PW12O403–) and benzalkonium chloride (BAC). Corrosion-resistant performances of the coatings in 0.1 M HCl showed that PPy composite coatings in the presence of phosphotungstic acid and BAC exhibit more effective protection for iron in comparison with PPy formed in 0.3 M oxalic acid, and corrosion resistance of PPy–BAC is better than PPy–PW12 even though PPy–PW12 shows nobler open-circuit potential for a longer period of time than PPy–BAC. Impedance measurements show that, after immersion of 12 h in 0.1 M HCl, the polarization resistances of PPy–PW12 and PPy–BAC coatings reach 1860 and 3110 Ω cm2, respectively, compared to 640 Ω cm2 of PPy deposited from 0.3 M oxalic acid.