Rare earth cerium-phenanthroline binary complex as a new corrosion inhibitor for carbon steel in acidic medium.

This paper synthesizes a Ce (III) complex with 1,10-phenanthroline (phen) as the ligand, whose chemical formula is confirmed as Ce(NO3)3(phen)2, and evaluate its inhibition effects on the corrosion of P110 carbon steel in 0.5 M HCl by electrochemical measurements, surface analyses and theoretical calculations. The results show that the Ce(NO3)3(phen)2 complex exhibits high corrosion inhibition efficiencies of ~ 95% at 298 K (25 °C) and ~ 90% at relatively high temperature of 328 K (55 °C), outperforming its cerium salt and ligand of phen. The highest corrosion inhibition efficiency of Ce(NO3)3(phen)2 corresponds to its highest thermodynamics parameters of activation energy (Ea), activation enthalpy (ΔHa) and activation entropy (ΔSa) and the equilibrium constant of adsorption (Kads). Surface analyses further confirm the superior corrosion inhibition performance of Ce(NO3)3(phen)2. Moreover, the X-ray photoelectron spectroscopy analysis indicate that Ce(NO3)3(phen)2 can inhibit corrosion by simultaneously forming adsorption film via its phen ligand and precipitation film via its Ce (III) complex, which could be the reason for its high corrosion inhibition performance at high temperature. DFT calculations and molecular dynamic simulation show a good correlation with the experimental results. [ABSTRACT FROM AUTHOR]